ORCID Profile
0000-0003-1267-6035
Current Organisations
Instituto Politécnico de Lisboa Instituto Superior de Engenharia de Lisboa
,
Griffith University - Gold Coast Campus
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Publisher: Oxford University Press (OUP)
Date: 27-09-2023
DOI: 10.1093/PTJ/PZAD130
Publisher: Wiley
Date: 03-2018
DOI: 10.14814/PHY2.13629
Publisher: Wiley
Date: 02-10-2017
DOI: 10.1111/CPF.12301
Abstract: The purpose of this study was to examine the effect of venous occlusion per se on forearm muscle blood flow, as determined by the near-infrared spectroscopy (NIRS) venous occlusion technique (NIRS-VOT). NIRS data were obtained from the flexor digitorum superficialis (FDS) muscle on the dominant arm of 16 young, ostensibly healthy participants (14 men and two women 30 ± 6 year 73 ± 7 kg). Participants completed a series of five venous occlusion trials while seated at rest, and a series of 12 venous occlusion trials during a reactive hyperaemia induced by 5 min of forearm arterial occlusion. The NIRS-VOT was used to assess FDS muscle blood flow (Q˙mus), beat-by-beat, over the first four cardiac beats during venous occlusions. Q˙mus was also reported as a cumulative value, wherein the first two, first three and first four cardiac beats were used to calculate muscle blood flow. We observed that Q˙mus was highest when calculated over the first cardiac beat during venous occlusions performed at rest and throughout reactive hyperaemia (P<0·05). Moreover, the inclusion of more than one cardiac beat in the calculation of Q˙mus underestimated muscle blood flows, irrespective of the prevailing level of arterial inflow. These findings support the idea that venous occlusion per se affects the measurement of Q˙mus via the NIRS-VOT. Accordingly, it is recommended that Q˙mus is determined over the first cardiac beat when using the NIRS-VOT to assess microvascular blood flow of human forearm muscles.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2020
Publisher: American Physiological Society
Date: 04-2017
DOI: 10.1152/JAPPLPHYSIOL.00114.2016
Abstract: It remains incompletely understood whether there is an association between the transcriptome profiles of skeletal muscle and blood leukocytes in response to exercise or other physiological stressors. We have previously analyzed the changes in the muscle and blood neutrophil transcriptome in eight trained men before and 3, 48, and 96 h after 2 h cycling and running. Because we collected muscle and blood in the same in iduals and under the same conditions, we were able to directly compare gene expression between the muscle and blood neutrophils. Applying weighted gene coexpression network analysis (WGCNA) as an advanced network-driven method to these original data sets enabled us to compare the muscle and neutrophil transcriptomes in a rigorous and systematic manner. Two gene networks were identified that were preserved between skeletal muscle and blood neutrophils, functionally related to mitochondria and posttranslational processes. Strong preservation measures ( Z summary 10) for both muscle-neutrophil gene networks were evident within the postexercise recovery period. Muscle and neutrophil gene coexpression was strongly correlated in the mitochondria-related network ( r = 0.97 P = 3.17E-2). We also identified multiple correlations between muscular gene subnetworks and exercise-induced changes in blood leukocyte counts, inflammation, and muscle damage markers. These data reveal previously unidentified gene coexpression between skeletal muscle and blood neutrophils following exercise, showing the value of WGCNA to understand exercise physiology. Furthermore, these findings provide preliminary evidence in support of the notion that blood neutrophil gene networks may potentially help us to track physiological and pathophysiological changes in the muscle. NEW & NOTEWORTHY By using weighted gene coexpression network analysis, an advanced bioinformatics method, we have identified previously unknown, functional gene networks that are preserved between skeletal muscle and blood neutrophils during recovery from exercise. These novel preliminary data suggest that muscular gene networks are coexpressed in blood leukocytes following physiological stress. This is a step forward toward the development of blood neutrophil gene subnetworks as part of blood biomarker panels to assess muscle health and disease.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2018
Publisher: Public Library of Science (PLoS)
Date: 30-11-2016
Publisher: European Respiratory Society (ERS)
Date: 09-08-2023
DOI: 10.1183/16000617.0016-2023
Abstract: Exertional dyspnoea is the primary diagnostic symptom for chronic cardiopulmonary disease populations. Whilst a number of exercise tests are used, there remains no gold standard clinical measure of exertional dyspnoea. The aim of this review was to comprehensively describe and evaluate all types of fixed-intensity exercise tests used to assess exertional dyspnoea in chronic cardiopulmonary populations and, where possible, report the reliability and responsiveness of the tests. A systematic search of five electronic databases identified papers that examined 1) fixed-intensity exercise tests and measured exertional dyspnoea, 2) chronic cardiopulmonary populations, 3) exertional dyspnoea reported at isotime or upon completion of fixed-duration exercise tests, and 4) published in English. Searches identified 8785 papers. 123 papers were included, covering exercise tests using a variety of fixed-intensity protocols. Three modes were identified, as follows: 1) cycling (n=87), 2) walking (n=31) and 3) other (step test (n=8) and arm exercise (n=2)). Most studies (98%) were performed on chronic respiratory disease patients. Nearly all studies (88%) used an incremental exercise test. 34% of studies used a fixed duration for the exercise test, with the remaining 66% using an exhaustion protocol recording exertional dyspnoea at isotime. Exertional dyspnoea was measured using the Borg scale (89%). 7% of studies reported reliability. Most studies (72%) examined the change in exertional dyspnoea in response to different interventions. Considerable methodological variety of fixed-intensity exercise tests exists to assess exertional dyspnoea and most test protocols require incremental exercise tests. There does not appear to be a simple, universal test for measuring exertional dyspnoea in the clinical setting.
Publisher: Elsevier BV
Date: 2009
Publisher: Elsevier BV
Date: 12-2014
DOI: 10.1016/J.APPET.2014.09.006
Abstract: Coffee is one of the most widely consumed beverages in the world and has a number of potential health benefits. Coffee may influence energy expenditure and energy intake, which in turn may affect body weight. However, the influence of coffee and its constituents - particularly caffeine - on appetite remains largely unexplored. The objective of this study was to examine the impact of coffee consumption (with and without caffeine) on appetite sensations, energy intake, gastric emptying, and plasma glucose between breakfast and lunch meals. In a double-blind, randomised crossover design. Participants (n = 12, 9 women Mean ± SD age and BMI: 26.3 ± 6.3 y and 22.7 ± 2.2 kg•m⁻²) completed 4 trials: placebo (PLA), decaffeinated coffee (DECAF), caffeine (CAF), and caffeine with decaffeinated coffee (COF). Participants were given a standardised breakfast labelled with ¹³C-octanoic acid and 225 mL of treatment beverage and a capsule containing either caffeine or placebo. Two hours later, another 225 mL of the treatment beverage and capsule was administered. Four and a half hours after breakfast, participants were given access to an ad libitum meal for determination of energy intake. Between meals, participants provided exhaled breath s les for determination of gastric emptying venous blood and appetite sensations. Energy intake was not significantly different between the trials (Means ± SD, p> 0.05 Placebo: 2118 ± 663 kJ Decaf: 2128 ± 739 kJ Caffeine: 2287 ± 649 kJ Coffee: 2016 ± 750 kJ) Other than main effects of time (p 0.05). Gastric emptying was not significantly different across trials (p > 0.05). No significant effects of decaffeinated coffee, caffeine or their combination were detected. However, the consumption of caffeine and/or coffee for regulation of energy balance over longer periods of time warrant further investigation.
Publisher: Elsevier BV
Date: 2009
Publisher: Oxford University Press (OUP)
Date: 27-09-2017
DOI: 10.1093/JXB/ERX300
Publisher: American Physiological Society
Date: 15-07-2013
Abstract: Although physiological tremor has been extensively studied within a single limb, tremor relationships between limbs are not well understood. Early investigations proposed that tremor in each limb is driven by CNS oscillators operating in parallel. However, recent evidence suggests that tremor in both limbs arises from shared neural inputs and is more likely to be observed under perturbed conditions. In the present study, postural tremor about the elbow joint and elbow flexor EMG activity were examined on both sides of the body in response to unilateral loading and fatiguing muscle contractions. Applying loads of 0.5, 1.0, 1.5, and 3.0 kg to a single limb increased tremor and muscle activity in the loaded limb but did not affect the unloaded limb, indicating that manipulating the inertial characteristics of a limb does not evoke bilateral tremor responses. In contrast, maximal-effort unilateral isometric contractions resulted in increased tremor and muscle activity in both the active limb and the nonactive limb without any changes in between-limb tremor or muscle coupling. When unilateral contractions were repeated intermittently, to the extent that maximum torque generation about the elbow joint declined by 50%, different tremor profiles were observed in each limb. Specifically, unilateral fatigue altered coupling between limbs and generated a bilateral response such that tremor and brachioradialis EMG decreased for the fatigued limb and increased in the contralateral nonfatigued limb. Our results demonstrate that activity in the nonactive limb may be due to a “spillover” effect rather than directly coupled neural output to both arms and that between-limb coupling for tremor and muscle activity is only altered under considerably perturbed conditions, such as fatigue-inducing contractions.
Publisher: Wiley
Date: 03-2022
DOI: 10.1111/RESP.14216
Publisher: Springer Science and Business Media LLC
Date: 18-04-2014
Publisher: BMJ
Date: 12-2004
Publisher: American Physiological Society
Date: 11-2023
Publisher: Springer Science and Business Media LLC
Date: 16-01-2010
DOI: 10.1007/S00421-009-1351-8
Abstract: The purpose of this study was to determine if improved supramaximal exercise performance in trained cyclists following caffeine ingestion was associated with enhanced O(2) uptake (VO2 kinetics), increased anaerobic energy provision (accumulated O(2)-AO(2)-deficit), or a reduction in the accumulation of metabolites (for ex le, K(+)) associated with muscular fatigue. Six highly trained male cyclists (VO2peak 68 +/- 8 mL kg(-1) min(-1)) performed supramaximal (120% VO2peak) exercise bouts to exhaustion on an electronically braked cycle ergometer, following double-blind and randomized ingestion of caffeine lacebo (5 mg kg(-1)). Time to exhaustion (TE), VO2 kinetics, AO(2) deficit, blood lactate (La(-)), plasma potassium (K(+)), caffeine and paraxanthine concentrations were measured. Caffeine ingestion elicited significant increases in TE (14.8%, p < 0.01) and AO(2) deficit (6.5%, p < 0.05). In contrast, no changes were observed in AO(2) deficit at isotime, VO2 kinetics, blood [La(-)] at exhaustion or peak [K(+)] following caffeine ingestion. However, [K(+)] was significantly reduced (13.4%, p < 0.01) during warm-up cycling immediately prior to the onset of the supramaximal bout for the caffeine trials, compared with placebo. It appears that caffeine ingestion is beneficial to supramaximal cycling performance in highly trained men. The reduced plasma [K(+)] during submaximal warm-up cycling may prolong the time taken to reach critical [K(+)] at exhaustion, thus delaying fatigue. Considering caffeine ingestion did not change VO2 kinetics or isotime AO(2) deficit, increases in absolute AO(2) deficit may be a consequence of prolonged TE, rather than causal.
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.RESP.2018.07.008
Abstract: We measured pulmonary gas exchange during six minute walk test (6MWT) in patients with idiopathic (IPAH) and congenital heart disease-related pulmonary hypertension (CHDPH), and determined the relationship between the degree of desaturation and changes in minute ventilation to carbon dioxide production V˙
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2017
Publisher: Springer Science and Business Media LLC
Date: 03-09-2018
Publisher: Elsevier BV
Date: 03-2023
DOI: 10.1016/J.HRTLNG.2022.11.010
Abstract: In heart failure (HF), exertional dyspnea is a common symptom, but validated field-based tests for its measurement are limited. The Dyspnea Challenge is a two-minute uphill treadmill walk designed to measure exertional dyspnea in cardiopulmonary disease. The purpose of this study was to establish the test-retest reliability of the Dyspnea Challenge in HF and to compare the exercise responses to a group with chronic obstructive pulmonary disease (COPD). The study was an experimental, single-blind, randomized, multi-site project that recruited in iduals with HF (New York Heart Association I-III) and COPD (Global Initiative for Chronic Obstructive Lung Disease II-IV). Participants completed two visits. On the first visit, participants performed two six-minute walk tests (6MWT), followed by two to three Dyspnea Challenges to calculate treadmill speed and gradient. At Visit Two, participants performed two separate Dyspnea Challenges, with one including measures of pulmonary gas exchange and central hemodynamics. Twenty-one in iduals with HF (10 female 66±11years ejection fraction:45.3 ± 6.1% six-minute distance(6MWD) 520 ± 97 m), and 25 COPD (11 female 68 ± 10 yr forced expiratory volume in 1 s:47.6 ± 11.5% 6MWD: 430 ± 101 m). Intraclass correlation coefficients demonstrated excellent test-retest reliability for HF (0.94, P<.01) and COPD (0.95, P<.01). While achieving similar end-exercise exertional dyspnea intensities (P=.60), the HF group walked at a higher average speed (4.2 ± 0.8 vs. 3.5 ± 0.8km·h The Dyspnea Challenge is a reliable test-retest measure of exertional dyspnea in HF. Typical to their pathologies, HF seemed limited by an inadequate modulation of cardiac output, while ventilatory constraints h ered those with COPD.
Publisher: Elsevier BV
Date: 09-2021
Publisher: American Physiological Society
Date: 02-2014
DOI: 10.1152/JAPPLPHYSIOL.00909.2013
Abstract: Reprogramming of gene expression is fundamental for skeletal muscle adaptations in response to endurance exercise. This study investigated the time course-dependent changes in the muscular transcriptome after an endurance exercise trial consisting of 1 h of intense cycling immediately followed by 1 h of intense running. Skeletal muscle s les were taken at baseline, 3 h, 48 h, and 96 h postexercise from eight healthy, endurance-trained men. RNA was extracted from muscle. Differential gene expression was evaluated using Illumina microarrays and validated with qPCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Three hours postexercise, 102 gene sets were upregulated [family wise error rate (FWER), P 0.05], including groups of genes related with leukocyte migration, immune and chaperone activation, and cyclic AMP responsive element binding protein (CREB) 1 signaling. Forty-eight hours postexercise, among 19 enriched gene sets (FWER, P 0.05), two gene sets related to actin cytoskeleton remodeling were upregulated. Ninety-six hours postexercise, 83 gene sets were enriched (FWER, P 0.05), 80 of which were upregulated, including gene groups related to chemokine signaling, cell stress management, and extracellular matrix remodeling. These data provide comprehensive insights into the molecular pathways involved in acute stress, recovery, and adaptive muscular responses to endurance exercise. The novel 96 h postexercise transcriptome indicates substantial transcriptional activity potentially associated with the prolonged presence of leukocytes in the muscles. This suggests that muscular recovery, from a transcriptional perspective, is incomplete 96 h after endurance exercise involving muscle damage.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2005
DOI: 10.1249/01.MSS.0000182497.43221.E1
Abstract: An increased recruitment of type II muscle fibers has been suggested as a major cause of the slow component of O(2) uptake (VO(2)) kinetics. Furthermore, the rise in plasma ammonia (NH(3)) during high-intensity exercise, where a slow component is observed, has been associated with the activation of type II muscle fibers. Therefore, the purpose of this study was to examine the relationship between the VO(2) slow component, plasma NH3 concentration, and electromyography (EMG) responses during constant-load cycling. Eight healthy adults (mean age +/- SEM: 21.4 +/- 1.0 yr) performed 7 min of heavy constant-load exercise. The breath-by-breath VO(2) response was characterized using a two-term exponential model. Plasma NH(3) concentration was measured at rest, following 3 min of unloaded cycling and at 3 and 7 min of constant-load exercise. Surface EMG activity of the right vastus lateralis muscle was measured during the final 10 s of every minute of exercise. The litude of the slow component was 561 +/- 52 mL.min(-1), and occurred 132 +/- 11 s following the onset of constant-load exercise. Plasma NH(3) concentration increased significantly from 3 to 7 min of constant-load exercise by 32.2 +/- 2.9 micromol.L(-1). The rise in plasma NH(3) concentration correlated significantly with the litude of the slow component (r = 0.79, P < 0.05). The mean power frequency of the EMG increased significantly while the integrated EMG/VO(2) ratio remained constant over the duration of the slow component. The rise in NH(3) concentration and the litude and spectral components of the EMG are consistent with a progressive increase in the recruitment of type II muscle fibers during the slow component phase of exercise.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2014
Publisher: BMJ
Date: 06-03-2019
DOI: 10.1136/THORAXJNL-2018-212683
Abstract: We examined the interactions between acoustically driven mood modulation and dyspnoea. Following familiarisation, 18 healthy participants attended three experimental sessions on separate days performing two 5 min treadmill tests with a 30 min interval per session while listening to either a positive, negative or neutral set of standardised International Affective Digitised Sounds (IADS). Participants rated intensity and affective domains of dyspnoea during the first exercise test and mood during the second. Mood valence was significantly higher when listening to positive (mean (95% CI): 6.5 (5.9–7.2)) compared with negative sounds (3.6 (2.9–4.4) p .001). Dyspnoea intensity and affect were statistically significantly lower when listening to positive (2.4 (1.8–2.9) and 1.3 (0.7–1.9)) compared with negative IADS (3.2 (2.3–3.7), p=0.013 and 2.3 (1.3–3.3), p=0.009). These findings indicate that acoustically induced mood changes influence exertional dyspnoea.
Publisher: Springer Science and Business Media LLC
Date: 28-01-2021
DOI: 10.1186/S40798-020-00297-0
Abstract: Rapid restoration of muscle glycogen stores is imperative for athletes undertaking consecutive strenuous exercise sessions with limited recovery time (e.g. ≤ 8 h). Strategies to optimise muscle glycogen re-synthesis in this situation are essential. This two-part systematic review and meta-analysis investigated the effect of consuming carbohydrate (CHO) with and without protein (PRO) on the rate of muscle glycogen re-synthesis during short-term post-exercise recovery (≤ 8 h). Studies were identified via the online databases Web of Science and Scopus. Investigations that measured muscle glycogen via needle biopsy during recovery (with the first measurement taken ≤ 30 min post-exercise and at least one additional measure taken ≤ 8 h post-exercise) following a standardised exercise bout (any type) under the following control vs. intervention conditions were included in the meta-analysis: part 1, water (or non-nutrient beverage) vs. CHO, and part 2, CHO vs. CHO+PRO. Publications were examined for methodological quality using the Rosendal scale. Random-effects meta-analyses and meta-regression analyses were conducted to evaluate intervention efficacy. Overall, 29 trials ( n = 246 participants) derived from 21 publications were included in this review. The quality assessment yielded a Rosendal score of 61 ± 8% (mean ± standard deviation). Part 1: 10 trials ( n = 86) were reviewed. Ingesting CHO during recovery (1.02 ± 0.4 g·kg body mass (BM) −1 h −1 ) improved the rate of muscle glycogen re-synthesis compared with water change in muscle glycogen (MG Δ ) re-synthesis rate = 23.5 mmol·kg dm −1 h −1 , 95% CI 19.0–27.9, p 0.001 I 2 = 66.8%. A significant positive correlation ( R 2 = 0.44, p = 0.027) was observed between interval of CHO administration (≤ hourly vs. hourly) and the mean difference in rate of re-synthesis between treatments. Part 2: 19 trials ( n = 160) were reviewed. Ingesting CHO+PRO (CHO: 0.86 ± 0.2 g·kg BM −1 h −1 PRO: 0.27 ± 0.1 g·kg BM −1 h −1 ) did not improve the rate of muscle glycogen re-synthesis compared to CHO alone (0.95 ± 0.3 g·kg BM −1 h −1 ) MG Δ re-synthesis rate = 0.4 mmol·kg dm −1 h −1 , 95% CI −2.7 to 3.4, p = 0.805 I 2 = 56.4%. Athletes with limited time for recovery between consecutive exercise sessions should prioritise regular intake of CHO, while co-ingesting PRO with CHO appears unlikely to enhance (or impede) the rate of muscle glycogen re-synthesis. Registered at the International Prospective Register of Systematic Reviews (PROSPERO) (identification code CRD42020156841 ).
Publisher: Mary Ann Liebert Inc
Date: 06-2021
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.RESP.2022.103915
Abstract: The Dyspnoea Challenge is a two-minute treadmill walk designed to measure exertional dyspnoea(ED). To efficiently in idualise workload, we aimed to assess 1) whether the Dyspnoea Challenge is responsive to 1% changes in treadmill gradient and 2) the minimum gradient variation necessary to generate a clinically meaningful change in ED (≥1 modified Borg scale). Thirty in iduals with COPD(GOLD II-IV) (age: 69.2 ± 9.2 years FEV Higher treadmill gradients generated stronger intensities of ED (3%:2.6 ± 1.8 4%:2.8 ± 2.2 5%:3.2 ± 2.2 6%:3.4 ± 2.2 7%:3.7 ± 1.8 8%:4.0 ± 2.1units). Statistical changes were observed in ED(e.g.,3 vs. 5%: P = .03) and the MDP discomfort data(e.g.,4 vs. 6%: P = .04) at ≥ a 2% variation in treadmill gradient. Linear regression found a 4% variation in treadmill gradient corresponded to a rise in ED ≥ 1unit. Increases in ED intensity corresponded to heightened sensations of work/effort(P < .01) and breathing frequency(P < .01). There were no changes in emotional constructs(P = .27). While there was an increase in HR with increasing gradient(P < .01), no differences were observed in end-exercise S To significantly change ED, the treadmill gradient must be manipulated by ≥ 2%, with a ≥ 4% change in gradient required to induce a clinically meaningful change in ED.
Publisher: Elsevier BV
Date: 06-2006
DOI: 10.1016/J.JSAMS.2006.03.024
Abstract: This study examined the relationship between minute ventilation (VE), CO2 production (VCO2), and blood lactate concentration ([La-]) during incremental exercise performed with reduced muscle glycogen stores. Nine untrained female subjects (25.3+/-4.2 year) performed incremental cycling in a normal glycogen (NG) state and under conditions of reduced muscle glycogen (RG) content. To reduce muscle glycogen stores, subjects cycled to exhaustion (124+/-33 min) at a power output corresponding to their gas-exchange anaerobic threshold. Peak oxygen uptake (VO2peak) was unchanged with glycogen reduction, even though subjects achieved a significantly lower maximal power output in the RG state (p<0.05). Peak blood [La-] decreased significantly by 37% in the RG state (p<0.001). At any percentage of VO2peak, O2 uptake and VE were similar for both treatment conditions, whereas VCO2 and respiratory exchange ratio values were lower during the RG trial than under NG conditions. Therefore, VE/VCO2 tended to be higher and end-tidal CO2 partial pressure tended to be lower during exercise performed in the RG state. VE was significantly correlated with VCO2 under both treatment conditions (NG: r=0.99, p<0.01 RG: r=0.99, p<0.01). However, the slope of the VE-VCO2 relationship was significantly elevated during the RG trial (p<0.01). VE during exercise was similar under both treatment conditions, even though VCO2 and blood [La-] were lower during the RG trial compared to the NG trial. This suggests that factors other than CO2 delivery to the lung and metabolic acidosis play an important role in regulating VE during exercise.
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.AMJCARD.2019.05.027
Abstract: Exercise stress echocardiograms (ESEs) are a functional cardiovascular (CV) test typically used for the investigation of coronary artery disease. ESEs are often terminated at a predetermined age-predicted maximum heart rate (APMHR) to facilitate timely acquisition of ultrasound images at peak exercise. Although an APMHR of 85% is often used, this has not been validated as a suitable termination end point. Heart rate blood pressure product (HRBPP) as an established measure of myocardial work may provide a more reliable assessment of cardiac workload. The aim of this study was to assess maximal HRBPP (MHRBPP) and APMHR as markers of cardiac workload during ESE, using CV events at mean follow-up as the outcome variable. After exclusions, 712 patients being investigated for ischemic heart disease, performed an ESE to volitional fatigue using the standard Bruce protocol. Patient demographics and test data were collected and patients followed for 4.4 ± 2.1 years. Cut-points for MHRBPP (25,060 area under curve 0.77) and APMHR (93.8% and 97.9% area under curve 0.71 p = 0.12 for difference) were established from receiver operating characteristic analysis. Those achieving an APMHR >85% but MHRBPP 25,060 regardless of APMHR (p <0.05). In conclusion, the current study demonstrates the superior prognostic power of MHRBPP over APMHR alone for the prediction of future CV events in patients performing an otherwise negative ESE for the detection of myocardial ischemia.
Publisher: American Physiological Society
Date: 10-2018
DOI: 10.1152/AJPREGU.00132.2018
Abstract: Heart failure (HF) patients are susceptible to heat strain during exercise, secondary to blunted skin blood flow (SkBF) responses, which may be explained by impaired nitric oxide (NO)-dependent vasodilation. Folic acid improves vascular endothelial function and SkBF through NO-dependent mechanisms in healthy older in iduals and patients with cardiovascular disease. We examined the effect of folic acid supplementation (5 mg/day for 6 wk) on vascular function [brachial artery flow-mediated dilation (FMD)] and SkBF responses [cutaneous vascular conductance (CVC)] during 60 min of exercise at a fixed metabolic heat production (300 Ẇ Hprod ) in a 30°C environment in 10 patients with HF (New York Heart Association Class I–II) and 10 healthy controls (CON). Serum folic acid concentration increased in HF [preintervention (pre): 1.4 ± 0.2 postintervention (post): 8.9 ± 6.7 ng/ml, P = 0.01] and CON (pre: 1.3 ± 0.6 post: 5.2 ± 4.9 ng/ml, P = 0.03). FMD improved by 2.1 ± 1.3% in HF ( P 0.01), but no change was observed in CON postintervention ( P = 0.20). During exercise, the external workload performed on the cycle ergometer to attain the fixed level of heat production for exercise was similar between groups (HF: 60 ± 13 CON: 65 ± 20 external workload, P = 0.52). Increases in CVC during exercise were similar in HF (pre: 0.89 ± 0.43 post: 0.83 ± 0.45 au/mmHg, P = 0.80) and CON (pre: 2.01 ± 0.79 post: 2.03 ± 0.72 au/mmHg, P = 0.73), although the values were consistently lower in HF for both pre- and postintervention measurement intervals ( P 0.05). These findings demonstrate that folic acid improves vascular endothelial function in patients with HF but does not enhance SkBF during exercise at a fixed metabolic heat production in a warm environment.
Publisher: Springer Science and Business Media LLC
Date: 16-06-2022
DOI: 10.1007/S40279-022-01706-Y
Abstract: Sleep loss may influence subsequent physical performance. Quantifying the impact of sleep loss on physical performance is critical for in iduals involved in athletic pursuits. Systematic review and meta-analysis. Studies were identified via the Web of Science, Scopus, and PsycINFO online databases. Investigations measuring exercise performance under ‘control’ (i.e., normal sleep, 6 h in any 24 h period) and ‘intervention’ (i.e., sleep loss, ≤ 6 h sleep in any 24 h period) conditions were included. Performance tasks were classified into different exercise categories (anaerobic power, speed ower endurance, high-intensity interval exercise (HIIE), strength, endurance, strength-endurance, and skill). Multi-level random-effects meta-analyses and meta-regression analyses were conducted, including subgroup analyses to explore the influence of sleep-loss protocol (e.g., deprivation, restriction, early [delayed sleep onset] and late restriction [earlier than normal waking]), time of day the exercise task was performed (AM vs. PM) and body limb strength (upper vs. lower body). Overall, 227 outcome measures (anaerobic power: n = 58 speed ower endurance: n = 32 HIIE: n = 27 strength: n = 66 endurance: n = 22 strength-endurance: n = 9 skill: n = 13) derived from 69 publications were included. Results indicated a negative impact of sleep loss on the percentage change (% Δ ) in exercise performance ( n = 959 [89%] male mean % Δ = − 7.56%, 95% CI − 11.9 to − 3.13, p = 0.001, I 2 = 98.1%). Effects were significant for all exercise categories. Subgroup analyses indicated that the pattern of sleep loss (i.e., deprivation, early and late restriction) preceding exercise is an important factor, with consistent negative effects only observed with deprivation and late-restriction protocols. A significant positive relationship was observed between time awake prior to the exercise task and % Δ in performance for both deprivation and late-restriction protocols (~ 0.4% decrease for every hour awake prior to exercise). The negative effects of sleep loss on different exercise tasks performed in the PM were consistent, while tasks performed in the AM were largely unaffected. Sleep loss appears to have a negative impact on exercise performance. If sleep loss is anticipated and unavoidable, in iduals should avoid situations that lead to experiencing deprivation or late restriction, and prioritise morning exercise in an effort to maintain performance.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2019
Publisher: European Respiratory Society
Date: 04-09-2022
Publisher: American Physiological Society
Date: 05-2012
DOI: 10.1152/AJPREGU.00406.2011
Abstract: Exercise triggers hormesis, conditioning hearts against damaging consequences of subsequent ischemia-reperfusion (I/R). We test whether “low-stress” voluntary activity modifies I/R tolerance and molecular determinants of cardiac survival. Male C57BL/6 mice were provided 7-day access to locked (7SED) or rotating (7EX) running-wheels before analysis of cardiac prosurvival (Akt, ERK 1/2) and prodeath (GSK3β) kinases, transcriptomic adaptations, and functional tolerance of isolated hearts to 25-min ischemia/45-min reperfusion. Over 7 days, 7EX mice increased running from 2.1 ± 0.2 to 5.3 ± 0.3 km/day (mean speed 38 ± 2 m/min), with activity improving myocardial I/R tolerance: 7SED hearts recovered 43 ± 3% of ventricular force with diastolic contracture of 33 ± 3 mmHg, whereas 7EX hearts recovered 63 ± 5% of force with diastolic dysfunction reduced to 23 ± 2 mmHg ( P 0.05). Cytosolic expression (total protein) of Akt and GSK3β was unaltered, while ERK 1/2 increased 30% in 7EX vs. 7SED hearts. Phosphorylation of Akt and ERK 1/2 was unaltered, whereas GSK3β phosphorylation increased ∼90%. Microarray interrogation identified significant changes (≥1.3-fold expression change, ≤5% FDR) in 142 known genes, the majority (92%) repressed. Significantly modified paths/networks related to inflammatory/immune function (particularly interferon-dependent), together with cell movement, growth, and death. Of only 14 induced transcripts, 3 encoded interrelated sarcomeric proteins titin, α-actinin, and myomesin-2, while transcripts for protective actin-stabilizing ND1-L and activator of mitochondrial biogenesis ALAS1 were also induced. There was no transcriptional evidence of oxidative heat-shock or other canonical “stress” responses. These data demonstrate that relatively brief voluntary activity substantially improves cardiac ischemic tolerance, an effect independent of shifts in Akt, but associated with increased total ERK 1/2 and phospho-inhibition of GSK3β. Transcriptomic data implicate inflammatory/immune and sarcomeric modulation in activity-dependent protection.
Publisher: Elsevier BV
Date: 07-2023
Publisher: IOP Publishing
Date: 26-02-2019
Abstract: Exercise treadmill testing (ETT) is a well-established procedure for the diagnosis, prognosis and functional assessment of patients with suspected cardiovascular disease. The use of handrail support during ETT is often discouraged as this has been demonstrated to overestimate functional capacity. It is unknown if this increase in functional capacity translates to an increase in cardiac workload. The aim of this study was to investigate if the use of handrail support during maximal ETT produces an increase in cardiac workload when compared to no handrail support. Fifty-two consenting volunteers performed two maximal ETTs, one with handrail support and the other without, approximately one week apart. Participants were identified as either experienced treadmill users (treadmill use ⩾ once per fortnight) (n = 24) or inexperienced users (n = 28). Cardiac workload was quantified using rate pressure product (RPP) (systolic blood pressure (SBP) × heart rate (HR)) Main results: The average age of participants was 38.4 ± 11.4 years (44% male). Overall exercise duration was significantly prolonged by 44.4% with handrail support (with support 15:01 ± 2:54 min without support 10:24 ± 2:09 min). Overall HR, SBP and maximum RPP were not significantly different between conditions. For the 28 inexperienced treadmill users maximum RPP was significantly higher during handrail support (7.5% increase) (with support 34 417 ± 4906 without support 31 821 ± 4565). Handrail support overestimates functional capacity, however produces greater maximal RPP in inexperienced treadmill users. If accurate aerobic data is required during ETT, or subjects performing ETT are experienced treadmill users, handrail support should be discouraged. Non-treadmill users or subjects fearful of falling may benefit from handrail support, particularly when maximal cardiac workload is desired.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-06-2020
DOI: 10.1249/MSS.0000000000002336
Abstract: Regional heterogeneity of the human heart plays an important role in left ventricular (LV) and right ventricular (RV) function and may contribute to enhanced myocardial efficiency in the athlete’s heart. This study comprehensively characterized regional and transmural myocardial tissue deformation (strain) in recreationally active (RA) and endurance-trained (ET) men to determine if regional nonuniformity evolves alongside morphological adaptations associated with endurance training. Echocardiography was used to measure LV and RV global, regional (apical, mid, basal) and transmural (endocardial, epicardial) longitudinal strain in 30 endurance-trained (ET) (age, 31 ± 2 yr body mass index, 23.1 ± 0.5 kg·m −2 V˙O 2peak , 60.2 ± 6.5 mL·kg −1 ·min −1 ) and 30 RA (age: 29 ± 2 yr body mass index, 23.4 ± 0.4 kg·m −2 V˙O 2peak : 42.6 ± 4.6 mL·kg −1 ·min −1 ). Nonuniformity was characterized using apex-to-base and transmural (endocardial-to-epicardial) strain gradients. Global longitudinal strain was similar in ET and RA in the left (−17.4% ± 0.4% vs −17.8% ± 0.5%, P = 0.662) and right ventricle (−25.8% ± 0.8% vs 26.4% ± 1.0%, P = 0.717). The apex-to-base strain gradient was greater in ET than RA in the left (−6.5% ± 0.7% vs −2.7% ± 0.8%, P = 0.001) and right ventricle (−9.6% ± 1.8% vs −3.0% ± 1.6%, P = 0.010). The LV transmural strain gradient was greater than RV in both groups, but similar in ET and RA (−4.7% ± 0.2% vs −4.7% ± 0.2%, P = 0.850), whereas RV transmural strain gradient was greater in ET than RA (−3.4% ± 0.3% vs −1.6% ± 0.4%, P = 0.003). RV apex-to-base and transmural strain gradients correlated with RV end-diastolic area ( R = 0.536 & 0.555, respectively, P 0.01) and V˙O 2peak ( R = 0.415 & 0.677, respectively, P 0.01). Transmural nonuniformity is more pronounced in the left ventricle than the RV free wall however, RV functional nonuniformity develops markedly after endurance training. Differences in myocardial architecture and exercise-induced wall stress in the left and right ventricles are possible explanations for the marked functional nonuniformity throughout the myocardium and in response to endurance exercise training.
Publisher: SAGE Publications
Date: 2008
DOI: 10.1177/0310057X0803600115
Abstract: A survey was conducted to assess the knowledge and trends of use of the pulmonary artery catheter amongst intensive care practitioners in Australasia. A 31-item multiple choice questionnaire, identical to one previously trialled in studies in the United States and Europe, was distributed to all registered intensive care specialists and trainees working in intensive care units in Australasia. Five-hundred-and-forty-one questionnaires were distributed and 151 (27.9%) were returned, with an average mark of 82.7%±9.3% and a range of 53.3 to 100%. Total score was significantly associated with years of experience in intensive care (P .04), number of pulmonary artery catheters inserted (P .015) and whether or not the respondent had passed the Joint Faculty of Intensive Care Medicine examination (P .01). Scores were significantly higher amongst trainees (P .0001) and physicians who had passed the Joint Faculty of Intensive Care Medicine examination (P .0001). Overall, 44.9% of respondents indicated their use of the pulmonary artery catheter was decreasing, with 42.6% indicating their use was the same over the past five years. Sixty-one percent of respondents indicated they either agreed or strongly agreed with the statement that the use of echocardiography should supersede the use of the pulmonary artery catheter by intensive care specialists in the future. We concluded that in this study, knowledge of the pulmonary artery catheter and its use is better in Australasia than in previous studies in North America and Europe. The majority of respondents in Australasia believe that echocardiography will supersede the use of the pulmonary artery catheter in the future.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-0011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2014
Publisher: Springer International Publishing
Date: 2019
Publisher: MDPI AG
Date: 08-01-2021
DOI: 10.3390/LIFE11010036
Abstract: Red blood cells (RBC) express a nitric oxide synthase isoform (RBC-NOS) that appears dependent on shear stress for Serine1177 phosphorylation. Whether this protein is equally activated by varied shears in the physiological range is less described. Here, we explored RBC-NOS Serine1177 phosphorylation in response to shear stress levels reflective of in vivo conditions. Whole blood s les were exposed to specific magnitudes of shear stress (0.5, 1.5, 4.5, 13.5 Pa) for discrete exposure times (1, 10, 30 min). Thereafter, RBC-NOS Serine1177 phosphorylation was measured utilising immunofluorescence labelling. Shear stress exposure at 0.5, 1.5, and 13.5 Pa significantly increased RBC-NOS Serine1177 phosphorylation following 1 min (p 0.0001) exposure to 4.5 Pa had no effect after 1 min. RBC-NOS Serine1177 phosphorylation was significantly increased following 10 min at each magnitude of shear stress (0.5, 1.5, 13.5 Pa, p 0.0001 4.5 Pa, p = 0.0042). Shear stress exposure for 30 min significantly increased RBC-NOS Serine1177 phosphorylation at 0.5 Pa and 13.5 Pa (p 0.0001). We found that RBC-NOS phosphorylation via shear stress is non-linear and differs for a given magnitude and duration of exposure. This study provides a new understanding of the discrete relation between RBC-NOS and shear stress.
Publisher: VM Media SP. zo.o VM Group SK
Date: 22-01-2020
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.APPET.2012.12.010
Abstract: The precise magnitude of the effect of acute exercise on subsequent energy intake is not well understood. Identifying how large a deficit exercise can produce in energy intake and whether this is compensated for, is important in design of long-term exercise programs for weight loss and weight maintenance. Thus, this paper sought to review and perform a meta-analysis on data from the existing literature. Twenty-nine studies, consisting of 51 trials, were identified for inclusion. Exercise duration ranged from 30 to 120min at intensities of 36-81% VO(2)max, with trials ranging from 2 to 14h, and ad libitum test meals offered 0-2h post-exercise. The outcome variables included absolute energy intake and relative energy intake. A random effects model was employed for analysis due to expected heterogeneity. Results indicated that exercise has a trivial effect on absolute energy intake (n=51 ES=0.14, 95% CI: -0.005 to 0.29) and a large effect on relative energy intake (creating an energy deficit, n=25 ES=-1.35, 95% CI: -1.64 to -1.05). Despite variability among studies, results suggest that exercise is effective for producing a short-term energy deficit and that in iduals tend not to compensate for the energy expended during exercise in the immediate hours after exercise by altering food intake.
Publisher: American Physiological Society
Date: 15-06-2013
DOI: 10.1152/JAPPLPHYSIOL.00143.2013
Abstract: Neutrophils serve as an intriguing model for the study of innate immune cellular activity induced by physiological stress. We measured changes in the transcriptome of circulating neutrophils following an experimental exercise trial (EXTRI) consisting of 1 h of intense cycling immediately followed by 1 h of intense running. Blood s les were taken at baseline, 3 h, 48 h, and 96 h post-EXTRI from eight healthy, endurance-trained, male subjects. RNA was extracted from isolated neutrophils. Differential gene expression was evaluated using Illumina microarrays and validated with quantitative PCR. Gene set enrichment analysis identified enriched molecular signatures chosen from the Molecular Signatures Database. Blood concentrations of muscle damage indexes, neutrophils, interleukin (IL)-6 and IL-10 were increased ( P 0.05) 3 h post-EXTRI. Upregulated groups of functionally related genes 3 h post-EXTRI included gene sets associated with the recognition of tissue damage, the IL-1 receptor, and Toll-like receptor (TLR) pathways (familywise error rate, P value 0.05). The core enrichment for these pathways included TLRs, low-affinity immunoglobulin receptors, S100 calcium binding protein A12, and negative regulators of innate immunity, e.g., IL-1 receptor antagonist, and IL-1 receptor associated kinase-3. Plasma myoglobin changes correlated with neutrophil TLR4 gene expression ( r = 0.74 P 0.05). Neutrophils had returned to their nonactivated state 48 h post-EXTRI, indicating that their initial proinflammatory response was transient and rapidly counterregulated. This study provides novel insight into the signaling mechanisms underlying the neutrophil responses to endurance exercise, suggesting that their transcriptional activity was particularly induced by damage-associated molecule patterns, hypothetically originating from the leakage of muscle components into the circulation.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-08-2022
Publisher: Oxford University Press (OUP)
Date: 20-09-2019
DOI: 10.1093/EHJCI/JEY131
Abstract: Non-invasive left ventricular (LV) pressure-strain loop (PSL) provides a novel method of quantifying myocardial work (MW) with potential advantages over conventional global longitudinal strain (GLS) by incorporating measurements of myocardial deformation and LV pressure. We investigated different patterns of LV PSL and global MW index (GWI) in patients with hypertension (HTN) and dilated cardiomyopathy (CMP). Seventy-four patients underwent transthoracic echocardiography and strain analysis before coronary angiography. Patients were ided into three groups: control, HTN, and CMP. GWI was calculated as the area of the LV PSL as a product of strain × systolic blood pressure. MW efficiency (GWE) is derived from the percentage ratio of constructive work (GCW) to sum of constructive work (GCW) and wasted work (GWW). Influences of HTN and LV function on its relationship with MW were evaluated. GLS and LV ejection fraction were preserved in the HTN group with no difference from controls. GWI was significantly higher in moderate to severe HTN patients (P = 0.004) as a compensatory mechanism to preserve LV contractility and function against an increase in afterload. GWE was preserved in HTN patients due to the proportional increase in GCW and GWW. GLS, GWI, and GWE were significantly reduced in CMP (P < 0.05), with a trend in rightward shift and reduction in the LV PSL. GWI is a potential new technique that allows better understanding of the relationship between LV remodelling and increased wall stress under different loading conditions.
Publisher: Wiley
Date: 23-05-2017
DOI: 10.1111/AOR.12890
Abstract: The supra-physiological shear stress that blood is exposed to while traversing mechanical circulatory assist devices affects the physical properties of red blood cells (RBCs), impairs RBC deformability, and may induce hemolysis. Previous studies exploring RBC damage following exposure to supra-physiological shear stress have employed durations exceeding clinical instrumentation, thus we explored changes in RBC deformability following exposure to shear stress below the reported "hemolytic threshold" using shear exposure durations per minute (i.e., duty-cycles) reflective of that employed by circulatory assist devices. Blood collected from 20 male donors, aged 18-38 years, was suspended in a viscous medium and exposed to an intermittent shear stress protocol of 1 s at 100 Pa, every 60 s for 60 duty-cycles. During the remaining 59 s/min, the cells were left at stasis until the subsequent duty-cycle commenced. At discrete time points (15/30/45/60 duty-cycles), an ektacytometer measured RBC deformability immediately after shear exposure at 100 Pa. Plasma-free hemoglobin, a measurement of hemolysis, was quantified via spectrophotometry. Supra-physiological shear stress impaired RBC properties, as indicated by: (1) decreased maximal elongation of RBCs at infinite shear stress following 15 duty-cycles (P <0.05) (2) increased real-time RBC deformability during application of the supra-physiological shear stress protocol (100 Pa) following exposure to 1 duty-cycle (F (1.891, 32.15) = 12.21, P = 0.0001) and (3) increased plasma-free hemoglobin following 60 duty-cycles (P < 0.01). The present study indicates that exposure of RBCs to short-term, repeated supra-physiological shear stress, impairs RBC deformability, with the extent of impairment exacerbated with each duty-cycle, and ultimately precipitates hemolysis.
Publisher: IOP Publishing
Date: 24-11-2014
DOI: 10.1088/0967-3334/35/12/2563
Abstract: The purpose of this study was to examine whether circulatory occlusion of the hand impacts on regional forearm muscle haemodynamics as determined by the near-infrared spectroscopy (NIRS) venous occlusion technique (NIRSVOT). Twenty-five young, healthy participants (18 males and 7 females 28 ± 4 years 71 ± 7 kg) completed two experimental protocols that were performed on the dominant arm: (1) a series of five venous occlusion trials with a suprasystolic cuff (>260 mmHg) applied to the wrist and (2) five venous occlusion trials without hand-occlusion. Both protocols were performed twice in a counterbalanced manner. NIRS data were obtained from the flexor digitorum superficialis (FDS) muscle using a dual wavelength, continuous-wave spectrophotometer. FDS muscle blood flow (Q(FDS)), vascular conductance (C(FDS)), O2 consumption (Vo(2FDS)), and venous O2 saturation (SvO2) were calculated from NIRS data during the initial 5 s of venous occlusion. Circulatory occlusion of the hand via wrist cuffing significantly (P < 0.05) reduced Q(FDS) (-36 ± 23%), CFDS (-37 ± 23%), Vo2(FDS) (-14 ± 31%) and SvO2 (-14 ± 12%). These findings indicate that hand-occlusion, via wrist cuffing, adversely impacts on regional forearm haemodynamics as determined by the NIRS-VOT. Consequently, it is recommended that future investigators avoid hand-occlusion when using the NIRS-VOT to quantify spontaneous haemodynamics of regional forearm muscle.
Publisher: Wiley
Date: 12-09-2021
DOI: 10.1111/ECHO.15194
Abstract: This study sought to determine the contractile reserve (CR) response to exercise stress echocardiography (ESE) quantified by the novel parameter, non-invasive myocardial work (MW), in subjects with angiographically proven coronary artery disease (CAD). CR was measured by the relative change in ejection fraction (EF), global longitudinal strain (GLS) and MW indices from rest to peak exercise in 304 patients referred for clinically indicated ESE. Positive ESE patients proceeded to coronary angiography and further risk stratified based on either percutaneous or surgical intervention. CR Multivessel disease requiring surgical revascularization have the greatest reduction in CR. MW may potentially improve detection of ischemia and further risk stratification during ESE to maximize the benefits of revascularization.
Publisher: American Physiological Society
Date: 15-04-2015
DOI: 10.1152/AJPHEART.00917.2014
Abstract: Transient reductions in myocardial strain coupled with cardiac-specific biomarker release have been reported after prolonged exercise ( min). However, it is unknown if 1) shorter-duration exercise (60 min) can perturb cardiac function or 2) if exercise-induced reductions in strain are masked by hemodynamic changes that are associated with passive recovery from exercise. Left ventricular (LV) and right ventricular global longitudinal strain (GLS), LV torsion, and high-sensitivity cardiac troponin T were measured in 15 competitive cyclists (age: 28 ± 3 yr, peak O 2 uptake: 4.8 ± 0.6 l/min) before and after a 60-min high-intensity cycling race intervention (CRIT 60 ). At both time points (pre- and post-CRIT 60 ), strain and torsion were assessed at rest and during a standardized low-intensity exercise challenge (power output: 96 ± 8 W) in a semirecumbent position using echocardiography. During rest, hemodynamic conditions were different from pre- to post-CRIT 60 (mean arterial pressure: 96 ± 1 vs. 86 ± 2 mmHg, P 0.001), and there were no changes in strain or torsion. In contrast, during the standardized low-intensity exercise challenge, hemodynamic conditions were unchanged from pre- to post-CRIT 60 (mean arterial pressure: 98 ± 1 vs. 97 ± 1 mmHg, not significant), but strain decreased (left ventricular GLS: −20.3 ± 0.5% vs. −18.5 ± 0.4%, P 0.01 right ventricular GLS: −26.4 ± 1.6% vs. −22.4 ± 1.5%, P 0.05), whereas LV torsion remained unchanged. Serum high-sensitivity cardiac troponin T increased by 345% after the CRIT 60 (6.0 ± 0.6 vs. 20.7 ± 6.9 ng/l, P 0.05). This study demonstrates that exercise-induced functional and biochemical cardiac perturbations are not confined to ultraendurance sporting events and transpire during exercise that is typical of day-to-day training undertaken by endurance athletes. The clinical significance of cumulative exposure to endurance exercise warrants further study.
Publisher: Elsevier BV
Date: 2013
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2018
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.CARDFAIL.2017.04.003
Abstract: Upon heat exposure, the thermoregulatory system evokes reflex increases in sweating and skin blood flow responses to facilitate heat dissipation and maintain heat balance to prevent the continuing rise in core temperature. These heat dissipating responses are mediated primarily by autonomic and cardiovascular adjustments which, if attenuated, may compromise thermoregulatory control. In patients with heart failure (HF), the neurohumoral and cardiovascular dysfunction that underpins this condition may potentially impair thermoregulatory responses and, consequently, place these patients at a greater risk of heat-related illness. The aim of this review is to describe thermoregulatory mechanisms and the factors that may increase the risk of heat-related illness in patients with HF. An understanding of the mechanisms responsible for impaired thermoregulatory control in HF patients is of particular importance, given the current and projected increase in frequency and intensity of heat waves, as well as the promotion of regular exercise as a therapeutic modality. Furthermore, novel therapeutic strategies that may improve thermoregulatory control in HF, and the clinical relevance of this work in this population will be discussed.
Publisher: Elsevier BV
Date: 2004
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2011
Publisher: Hindawi Limited
Date: 02-08-2018
DOI: 10.1155/2018/8306154
Abstract: Climate change is predicted to bring about a greater variability in weather patterns with an increase in extreme weather events such as sustained heat waves. This change may have a direct impact on population health since heat waves can exceed the physiological limit of compensability of vulnerable in iduals. Indeed, many clinical reports suggest that in iduals over the age of 60 years are consistently the most vulnerable, experiencing significantly greater adverse heat-related health outcomes than any other age cohort during environmental heat exposure. There is now evidence that aging is associated with an attenuated physiological ability to dissipate heat and that the risk of heat-related illness in these in iduals is elevated, particularly when performing physical activity in the heat. The purpose of this review is to discuss mechanisms of thermoregulatory control and the factors that may increase the risk of heat-related illness in older in iduals. An understanding of the mechanisms responsible for impaired thermoregulation in this population is of particular importance, given the current and projected increase in frequency and intensity of heat waves, as well as the promotion of regular exercise as a means of improving health-related quality of life and morbidity and mortality. As such, the clinical implications of this work in this population will be discussed.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2015
Publisher: American Physiological Society
Date: 07-2022
Abstract: By combining TMS and motor nerve stimulation during a low-intensity exercise task, we were able to uncover the contribution that different levels of the CNS have during fatiguing exercise in PwMS. Our findings are novel and revealed that PwMS experienced decreased voluntary drive from the motor cortex during a low-intensity sustained fatiguing task that was associated with heightened levels of performance fatigability.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2013
Publisher: Oxford University Press (OUP)
Date: 12-01-2021
DOI: 10.1093/GJI/GGAB005
Abstract: We present PRISM3D, a 3-D reference seismic model of P- and S-wave velocities for Iberia and adjacent areas. PRISM3D results from the combination of the most up-to-date earth models available for the region. It extends horizontally from 15°W to 5°E in longitude, 34°N to 46°N in latitude and vertically from 3.5 km above to 200 km below sea level, and is modelled on a regular grid with 10 and 0.5 km of grid node spacing in the horizontal and vertical directions, respectively. It was designed using models inferred from local and teleseismic body-wave tomography, earthquake and ambient noise surface wave tomography, receiver function analysis and active source experiments. It includes two interfaces, namely the topography/bathymetry and the Mohorovičić (Moho) discontinuity. The Moho was modelled from previously published receiver function analysis and deep seismic sounding results. To that end we used a probabilistic surface reconstruction algorithm that allowed to extract the mean of the Moho depth surface along with its associated standard deviation, which provides a depth uncertainty estimate. The Moho depth model is in good agreement with previously published models, although it presents slightly sharper gardients in orogenic areas such as the Pyrenees or the Betic-Rif system. Crustal and mantle P- and S-wave wave speed grids were built separately on each side of the Moho depth surface by weighted average of existing models, thus allowing to realistically render the speed gradients across that interface. The associated weighted standard deviation was also calculated, which provides an uncertainty estimation on the average wave speed values at any point of the grid. At shallow depths (& km), low P and S wave speeds and high VP/VS are observed in offshore basins, while the Iberian Massif, which covers a large part of western Iberia, appears characterized by a rather flat Moho, higher than average VP and VS and low VP/VS. Conversely, the Betic-Rif system seems to be associated with low VP and VS, combined with high VP/VS in comparison to the rest of the study area. The most prominent feature of the mantle is the well known high wave speed anomaly related to the Alboran slab imaged in various mantle tomography studies. The consistency of PRISM3D with previous work is verified by comparing it with two recent studies, with which it shows a good general agreement.The impact of the new 3-D model is illustrated through a simple synthetic experiment, which shows that the lateral variations of the wave speed can produce traveltime differences ranging from –1.5 and 1.5 s for P waves and from –2.5 and 2.5 s for S waves at local to regional distances. Such values are far larger than phase picking uncertainties and would likely affect earthquake hypocentral parameter estimations. The new 3-D model thus provides a basis for regional studies including earthquake source studies, Earth structure investigations and geodynamic modelling of Iberia and its surroundings.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2013
Publisher: Wiley
Date: 24-12-2019
DOI: 10.1113/EP088226
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2017
Publisher: Wiley
Date: 06-12-2016
DOI: 10.1113/EP085423
Publisher: Oxford University Press (OUP)
Date: 04-07-2017
DOI: 10.1093/EHJCI/JEW128
Abstract: Strenuous endurance exercise acutely increases myocardial wall stress and evokes transient functional cardiac perturbations. However, it is unclear whether exercise-induced functional cardiac disturbances are ubiquitous throughout the myocardium or are segment specific. The aim of this study was to examine the influence of high-intensity endurance exercise on global and segmental left (LV) and right (RV) ventricular tissue deformation (strain). Echocardiography was used to measure strain in 23 active men (age: 28 ± 2 years VO2 peak: 4.5 ± 0.7 L min-1) at rest and during a standardized low-intensity exercise challenge, before and after a 90-min high-intensity endurance cycling intervention. Following the cycling intervention, LV and RV global strain decreased at rest (LV: -18.4 ± 0.4% vs. -17.7 ± 0.4%, P < 0.05 RV: -27.6 ± 0.7% vs. -26.4 ± 0.6%, P < 0.05) and by a greater extent during the low-intensity exercise challenge (LV: -21.3 ± 0.4% vs. -19.2 ± 0.5%, P < 0.01 RV: -28.4 ± 0.8% vs. -23.5 ± 0.9%, P < 0.01). Reductions in LV strain were unique to regions of RV attachment (e.g. LV septum: -24.4 ± 0.5% vs. -21.4 ± 0.6%, P < 0.01) with lateral (-18.9 ± 0.4% vs. -18.4 ± 0.5%) and posterior segments (-19.5 ± 0.4% vs. -18.8 ± 0.7%) unaffected. Similarly, augmentation of strain from rest to exercise was abolished in the RV free wall (-1.1 ± 1.0% vs. 2.9 ± 1.2%, P < 0.01), reduced in the septum (-4.6 ± 0.4% vs. -2.4 ± 0.5%, P < 0.01), and unchanged in the lateral (-1.2 ± 0.6% vs. -0.9 ± 0.6%) and posterior walls (-1.7 ± 0.6% vs. -1.3 ± 0.7%). Changes in ventricular strain following high-intensity exercise are more profound in the right ventricle than in the left ventricle. Reductions in LV strain were unique to the septal myocardium and may reflect ventricular interactions secondary to exercise-induced RV dysfunction.
Publisher: Springer Science and Business Media LLC
Date: 07-07-2012
DOI: 10.1007/S00421-011-2055-4
Abstract: The present study investigated whether 'break-points' in breathing pattern correspond to the first ([Formula: see text]) and second gas-exchange thresholds ([Formula: see text]) during incremental cycling. We used polynomial spline smoothing to detect accelerations and decelerations in pulmonary gas-exchange data, which provided an objective means of 'break-point' detection without assumption of the number and shape of said 'break-points'. Twenty-eight recreational cyclists completed the study, with five in iduals excluded from analyses due to low signal-to-noise ratios and/or high risk of 'pseudo-threshold' detection. In the remaining participants (n = 23), two separate and distinct accelerations in respiratory frequency (f (R)) during incremental work were observed, both of which demonstrated trivial biases and reasonably small ±95% limits of agreement (LOA) for the [Formula: see text] (0.2 ± 3.0 ml O(2) kg(-1) min(-1)) and [Formula: see text] (0.0 ± 2.4 ml O(2) kg(-1) min(-1)), respectively. A plateau in tidal volume (V (T)) data near the [Formula: see text] was identified in only 14 in iduals, and yielded the most unsatisfactory mean bias ±LOA of all comparisons made (-0.4 ± 5.3 ml O(2) kg(-1) min(-1)). Conversely, 18 in iduals displayed V (T)-plateau in close proximity to the [Formula: see text] evidenced by a mean bias ± LOA of 0.1 ± 3.1 ml O(2) kg(-1) min(-1). Our findings suggest that both accelerations in f (R) correspond to the gas-exchange thresholds, and a plateau (or decline) in V (T) at the [Formula: see text] is a common (but not universal) feature of the breathing pattern response to incremental cycling.
Publisher: Springer Science and Business Media LLC
Date: 24-11-2016
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.RESP.2007.01.006
Abstract: This study compared the use of a simple verbal 0-10 numerical rating scale (verbal NRS) and a visual analog scale (VAS) for the rating of dyspnea during exercise in a group of young and older subjects. Twelve younger (32+/-9 yr) and 12 older (71+/-7 yr) subjects used either the verbal NRS or the VAS in a randomised fashion to rate dyspnea during 60 s of uphill treadmill walking (range 5.6-8.8 km h(-1)) performed at either a low (17% grade) or high workload (26% grade) and then during recovery. Rating scales were evaluated twice on separate days (day 1 and day 2) at each workload. While the verbal NRS scores proved to be reliable throughout exercise and recovery, VAS scores were significantly (p<0.05) lower on day 2 during the low workload test (younger group) and the high workload test (older group). Verbal NRS ratings were consistently greater than VAS ratings at both workloads (p<0.001) for both young and older groups. The intra-class correlation coefficients for rating peak dyspnea using either the VAS or verbal NRS were consistently lower for the older subjects (range: r=0.54-0.67) than the younger subjects (range: r=0.70-0.86). Overall, subjects preferred the verbal NRS to the VAS. These results suggest that the verbal NRS compares favourably with the VAS for rating dyspnea during exercise without mask or mouthpiece. However, when rating peak dyspnea both scales appear less reliable when used by the older compared to young subjects.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2014
DOI: 10.1007/S00421-014-2827-8
Abstract: Critical power (CP), and the finite capacity to perform work above CP (W'), can be determined using a 3-min "all-out" cycling test (3MT). This protocol requires two laboratory visits: an incremental exercise test, followed by a 3MT on a separate day. The purpose of this study was to establish whether an incremental exercise test and a 3MT performed during a single laboratory visit can be used to accurately determine CP and W'. Twelve participants completed two experimental protocols: (1) Combined protocol: an incremental exercise test followed by a 3MT, with 20 min of recovery between exercise bouts and (2) Independent protocol: the conventional 3MT protocol, performed on a separate day. CP determined from the Combined (254 ± 117 W) and Independent (256 ± 118 W) protocols were not different (p = 0.40). Similarly, W' was not different (p = 0.96) between the Combined (13.7 ± 3.9 kJ) and Independent (13.7 ± 4.5 kJ) protocols. Linear regression revealed a strong level of measurement agreement between the protocols for CP and W', evidenced by high R(2) values (≥0.85) and marginal standard errors of the estimates (CP = 5 W W' = 1.81 kJ). A Combined protocol, consisting of an incremental exercise test followed by a 3MT, provides an accurate and valid method to determine an in idual's CP and, to a lesser extent, W'. Furthermore, this protocol permits the measurement of the gas-exchange threshold and peak O2 uptake and, consequently, the moderate, heavy, and severe exercise-intensity domains may be defined within a single exercise-testing session.
Publisher: Wiley
Date: 06-2016
DOI: 10.1113/JP272480
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.RESP.2022.103941
Abstract: The Dyspnoea Challenge has been developed to facilitate the field-based measure of exertional dyspnoea(ED). To further validate the test, we aimed to investigate the relationship between end-exercise ED, generated by a fixed-intensity Dyspnoea Challenge(DC Thirty-two in iduals (15 female) with COPD (GOLD II-IV) (age: 69.7 ± 9.4 yrs FEV End-exercise ED measured during the DC The Dyspnoea Challenge is correlated to different parameters of disease severity and produces a similar physiological and ED response to that of the 6MWT with the added benefit of being appropriate for longitudinal assessment of ED.
Publisher: Springer Science and Business Media LLC
Date: 19-02-2015
DOI: 10.1007/S00421-015-3133-9
Abstract: To examine the influence of estradiol on muscle damage and leg strength after intense eccentric exercise. Eight men (MEN), eight normally menstruating women (WomenNM), and eight women using oral contraceptives (WomenOC) participated in this study. Subjects performed 240 maximal-effort bilateral eccentric contractions of the quadriceps muscle groups designed to elicit exercise-induced muscle damage (EiMD). Serum creatine kinase (CK), myoglobin (Mb), and fatty acid-binding protein (FABP) concentrations were measured before (pre-) EiMD, as well as 0, 6, 24, and 48 h post-EiMD. Peak isometric quadriceps torque (i.e., leg strength) was measured pre-EiMD, as well as 24 and 48 h post-EiMD. The increases in CK, Mb, and FABP concentrations from pre- to post-EiMD were greater in MEN (10-fold, 15-fold, and fourfold, respectively) and WomenOC (sevenfold, 11-fold, and ninefold) compared with WomenNM (five-, six-, and threefold p < 0.05). The decline in leg strength was about 10 % pre- to 24 h post-EiMD in all groups and decreased a further 10-15 % by 48 h post-EiMD in the MEN and WomenOC only. Our findings suggest an important role of estradiol in blunting the muscle damage response to intense eccentric exercise and preserving muscle function after EiMD.
Publisher: Georg Thieme Verlag KG
Date: 21-09-2012
Publisher: American Physiological Society
Date: 10-2014
DOI: 10.1152/JAPPLPHYSIOL.00570.2014
Abstract: Combining an exercise and nutritional intervention is arguably the optimal method of creating energy imbalance for weight loss. This study sought to determine whether combining exercise and caffeine supplementation was more effective for promoting acute energy deficits and manipulations to substrate metabolism than exercise alone. Fourteen recreationally active participants (mean ± SD body mass index: 22.7 ± 2.6 kg/m 2 ) completed a resting control trial (CON), a placebo exercise trial (EX), and a caffeine exercise trial (EX+CAF, 2 × 3 mg/kg of caffeine 90 min before and 30 min after exercise) in a randomized, double-blinded design. Trials were 4 h in duration with 1 h of rest, 1 h of cycling at ∼65% power at maximum O 2 consumption or rest, and a 2-h recovery. Gas exchange, appetite perceptions, and blood s les were obtained periodically. Two hours after exercise, participants were offered an ad libitum test meal where energy and macronutrient intake were recorded. EX+CAF resulted in significantly greater energy expenditure and fat oxidation compared with EX (+250 kJ +10.4 g) and CON (+3,126 kJ +29.7 g) ( P 0.05). A trend for reduced energy and fat intake compared with CON (−718 kJ −8 g) ( P = 0.055) was observed. Consequently, EX+CAF created a greater energy deficit ( P 0.05). Caffeine also led to exercise being perceived as less difficult and more enjoyable ( P 0.05). Combining caffeine with exercise creates a greater acute energy deficit, and the implications of this protocol for weight loss or maintenance over longer periods of time in overweight/obese populations should be further investigated.
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.RESP.2021.103826
Abstract: Exertional dyspnoea(ED) is a hallmark of chronic obstructive pulmonary disease(COPD). We examined the repeatability and face validity of the end-exercise ED(ED Twenty-six in iduals with COPD(13 Females, age:69 ± 5.5yrs, FEV Mean 6MWT distance was 488 ± 58 m. End-exercise ED and HR were higher in the HI The Dyspnoea Challenge is a simple measure of ED that appears to have both repeatability and face validity. With further optimisation, this test may enhance the field-based clinical assessment of ED.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Wiley
Date: 14-10-2021
DOI: 10.1002/AJUM.12229
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2018
Publisher: Society for Industrial & Applied Mathematics (SIAM)
Date: 2014
DOI: 10.1137/130918915
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2018
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2018
Publisher: Oxford University Press (OUP)
Date: 08-2018
Publisher: Wiley
Date: 11-2016
DOI: 10.14814/PHY2.13022
Publisher: Springer Science and Business Media LLC
Date: 15-03-2021
Publisher: Public Library of Science (PLoS)
Date: 07-01-2016
Publisher: Wiley
Date: 06-08-2015
DOI: 10.1111/ECHO.13020
Abstract: Left ventricular (LV) twist mechanics are routinely assessed via echocardiography in clinical and research trials investigating the function of obliquely oriented myocardial fibers. However, echocardiograph-derived measures of LV twist may be compromised by nonstandardized acquisition of the apical image. This study examined the reproducibility of echocardiograph-derived parameters of apical twist mechanics at multiple levels of the apical myocardium. Two sets of 2D LV parasternal short-axis images were obtained in 30 healthy subjects (24 men 19-57 year) via echocardiography. Images were acquired immediately distal to the papillary muscles (apical image 1), immediately above the point of LV cavity obliteration at end systole (apical image 3), and midway between apical image 1 and apical image 3 (apical image 2). Repeat scans were performed within 1 hour, and twist mechanics (rotation and rotation rate) were calculated via frame-by-frame tracking of natural acoustic echocardiographic markers (speckle tracking). The magnitude of apical rotation increased progressively toward the apex (apical image 1: 4.2 ± 2.1°, apical image 2: 7.2 ± 3.9°, apical image 3: 11.8 ± 4.6°). apical images 1, 2, and 3 each had moderate to good correlations between repeat scans (ICC: 0.531-0.856). When apical images 1, 2, and 3 were averaged, rotation was 7.7 ± 2.7° and between-scan correlation was excellent (ICC: 0.910). Similar results were observed for systolic and diastolic rotation rates. Averaging multiple standardized apical images, tending progressively toward the apex, generated the most reproducible rotation indices and may be optimal for the assessment of LV twist mechanics across therapeutic, interventional, and research studies however, care should be taken given the influence of acquisition level on the magnitude of apical rotation.
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.ECHO.2019.02.014
Abstract: Noninvasive detection of functionally significant coronary artery disease (CAD) by echocardiography remains challenging, with the need to perform stress imaging to detect ischemia. The aim of this study was to determine whether global myocardial work (MW), derived from noninvasive left ventricular (LV) pressure-strain loops at rest, can predict significant CAD in patients without regional wall motion abnormalities and preserved LV ejection fraction (EF). One hundred and fifteen patients referred for coronary angiography who had EF ≥ 55%, no resting regional wall motion abnormalities, and no chest pain were assessed using echocardiography. Global MW was derived from noninvasive LV pressure-strain loops constructed from speckle-tracking echocardiography indexed to brachial systolic blood pressure. Global constructive work represented the sum of positive work due to myocardial shortening during systole and negative work due to lengthening during isovolumic relaxation. Global wasted work represented energy loss by myocardial lengthening in systole and shortening in isovolumic relaxation. Global MW efficiency was derived from the percentage ratio of constructive work to the sum of constructive work and wasted work. Patients with significant CAD demonstrated a significantly reduced global MW (P < .001) compared with those without CAD. Global longitudinal strain was significantly reduced (P < .001) in patients with multivessel CAD but not those with single-vessel CAD (P = .47). Receiver operating characteristic curve analysis demonstrated that global MW was the most powerful predictor of significant CAD (area under the curve = 0.786) and was superior to global longitudinal strain (area under the curve = 0.693). The optimal cutoff global MW value to predict significant CAD was 1,810 mm Hg% (sensitivity, 92% specificity, 51%). Noninvasive global MW derived using LV pressure-strain loops at rest is a more sensitive index than global longitudinal strain to detect significant CAD in patients with no regional wall motion abnormalities and normal EF. This is a potential valuable clinical tool to assist in the early diagnosis of CAD.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2016
Publisher: Springer Science and Business Media LLC
Date: 31-10-2014
DOI: 10.1007/S40279-013-0120-3
Abstract: Understanding of the impact of an acute bout of exercise on hormones involved in appetite regulation may provide insight into some of the mechanisms that regulate energy balance. In resting conditions, acylated ghrelin is known to stimulate food intake, while hormones such as peptide YY (PYY), pancreatic polypeptide (PP) and glucagon-like peptide 1 (GLP-1) are known to suppress food intake. The objective of this review was to determine the magnitude of exercise effects on levels of gastrointestinal hormones related to appetite, using systematic review and meta-analysis. Additionally, factors such as the exercise intensity, duration and mode, in addition to participant characteristics, were examined to determine their influence on these hormones. Major databases (PubMed, Scopus, Google Scholar, Science Direct, Academic Search Premier and EBSCOHost) were searched, through February 2013, for original studies, abstracts, theses and dissertations that examined responses of appetite hormones to acute exercise. Studies were included if they evaluated appetite hormone responses during and in the hours after an acute bout of exercise and reported area under the concentration-time curve (AUC) values for more than three datapoints. Studies reporting mean or pre ost-values only were excluded. Initially, 75 studies were identified. After evaluation of study quality and validity, using the Physiotherapy Evidence Database scale, data from 20 studies (28 trials) involving 241 participants (77.6 % men) had their data extracted for inclusion in the meta-analyses. A random-effects meta-analysis was conducted for acylated ghrelin (n = 18 studies, 25 trials) and PYY (n = 8 studies, 14 trials), with sub-group analyses and meta-regressions being conducted for moderator variables. Because the number of studies was limited, fixed-effects meta-analyses were performed on PP data (n = 4 studies, 5 trials) and GLP-1 data (n = 5 studies, 8 trials). The results of the meta-analyses indicated that exercise had small to moderate effects on appetite hormone levels, suppressing acylated ghrelin (effect size [ES] Cohen's d value -0.20, 95 % confidence interval [CI] -0.373 to -0.027 median decrease 16.5 %) and increasing PYY (ES 0.24, 95 % CI 0.007 to 0.475 median increase 8.9 %), GLP-1 (ES 0.275, 95 % CI -0.031 to 0.581 median increase 13 %), and PP (ES 0.50, 95 % CI 0.11 to 0.89 median increase 15 %). No significant heterogeneity was detected in any meta-analysis (using Cochrane's Q and I (2)) however, publication biases were detected for all analyses. No moderator variables were observed to moderate the variability among the studies assessing acylated ghrelin and PYY. The majority of the present literature is acute in nature therefore, longer-term alterations in appetite hormone concentrations and their influence on food and beverage intake are unknown. Furthermore, our review was limited to English-language studies and studies reporting AUC data. An acute bout of exercise may influence appetite by suppressing levels of acylated ghrelin while simultaneously increasing levels of PYY, GLP-1 and PP, which may contribute to alterations in food and drink intake after acute exercise. Further longitudinal studies and exploration into mechanisms of action are required in order to determine the precise role these hormones play in long-term appetite responses to an exercise intervention.
Publisher: American Physiological Society
Date: 09-2023
DOI: 10.1152/AJPREGU.00017.2023
Abstract: In vitro investigations demonstrate that human erythrocytes synthesize nitric oxide via a functional isoform of endothelial nitric oxide synthase (NOS) (RBC-NOS). We tested the hypothesis that phosphorylation of RBC-NOS at serine residue 1177 (RBC-NOS 1177 ) would be lified in blood draining-active skeletal muscle. Furthermore, given hypoxemia modulates local blood flow and thus shear stress, and nitric oxide availability, we performed duplicate experiments under normoxia and hypoxia. Nine healthy volunteers performed rhythmic handgrip exercise at 60% of in idualized maximal workload for 3.5 min while breathing room air (normoxia) and after being titrated to an arterial oxygen saturation ≈80% (hypoxemia). We measured brachial artery blood flow by high-resolution duplex ultrasound, while continuously monitoring vascular conductance and mean arterial pressure using finger photoplethysmography. Blood was s led during the final 30 s of each stage from an indwelling cannula. Blood viscosity was measured to facilitate calculation of accurate shear stresses. Erythrocytes were assessed for levels of phosphorylated RBC-NOS 1177 and cellular deformability from blood collected at rest and during exercise. Forearm exercise increased blood flow, vascular conductance, and vascular shear stress, which coincided with a 2.7 ± 0.6-fold increase in RBC-NOS 1177 phosphorylation ( P 0.0001) and increased cellular deformability ( P 0.0001) under normoxia. When compared with normoxia, hypoxemia elevated vascular conductance and shear stress ( P 0.05) at rest, while cellular deformability ( P 0.01) and RBC-NOS 1177 phosphorylation ( P 0.01) increased. Hypoxemic exercise elicited further increases in vascular conductance, shear stress, and cell deformability ( P 0.0001), although a subject-specific response in RBC-NOS 1177 phosphorylation was observed. Our data yield novel insights into the manner that hemodynamic force and oxygen tension modulate RBC-NOS in vivo.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 17-07-2019
DOI: 10.1249/MSS.0000000000002095
Abstract: The aim of this study was to determine whether muscle oxidative capacity is influenced by alterations in training volume in middle-distance runners. Twenty-four highly trained middle-distance runners ( n = 16 males V˙O 2peak = 73.3(4.3) mL·kg −1 ·min −1 n = 8 females, V˙O 2peak = 63.2(3.4) mL·kg −1 ·min −1 ) completed 3 wk of normal training (NormTr), 3 wk of high-volume training (HVTr a 10%, 20%, and 30% increase in training volume during each successive week from NormTr), and a 1-wk taper (TapTr 55% exponential reduction in training volume from HVTr week 3). Before and immediately after each training period, the rate of recovery of muscle oxygen consumption (mV˙O 2 ) of the gastrocnemius medialis was measured using near-infrared spectroscopy, with the rate constant indicating muscle oxidative capacity. Time to exhaustion (TTE) and V˙O 2peak were determined during a maximal incremental treadmill test. Twelve subjects were classified as being functionally overreached (FOR) after HVTr (decreased running TTE and high perceived fatigue), whereas the other 12 subjects were classified as acutely fatigued (AF no decrease in running TTE). The AF group demonstrated a significant increase in muscle oxidative capacity after HVTr (rate constant: 15.1% ± 9.7% min −1 P = 0.009), with no further improvement after TapTr, whereas there was no change in muscle oxidative capacity for FOR at any time point ( P 0.05). Compared with the FOR group, the AF group had substantially larger improvements in TTE from pre-HVTr to post-TapTr (FOR, 8.8% ± 3.7% AF, 3.2% ± 3.0% P = 0.04). The present study was able to demonstrate that muscle oxidative capacity was increased in response to a period of HVTr, but only in runners who did not develop FOR. Furthermore, runners who did not develop FOR had substantially larger performance improvements after a taper period.
Publisher: Informa UK Limited
Date: 2009
DOI: 10.3109/09638280902980928
Abstract: The purpose of this study was to examine the perceived benefits and barriers to exercise participation in persons with multiple sclerosis (MS). A cross-sectional postal survey comprised of 93 adults with MS was conducted. Participants completed the Exercise Benefits and Barriers Scale (EBBS), Spinal Cord Injury Exercise Self-Efficacy Scale (EXSE), Multiple Sclerosis Impact Scale, Disease Steps Scale and International Physical Activity Questionnaire. Forty-three percent of the participants were classified as exercising in iduals (EX group) as compared with non-exercising in iduals (non-EX group). Participants in the EX group reported significantly higher scores on the EBBS and EXSE. Items related to physical performance and personal accomplishment were cited as the greatest perceived benefits to exercise participation and those items related to physical exertion as the greatest perceived barriers to both the EX and non-EX groups. When compared with previous studies conducted in the general population, the participants in the present study reported different perceived barriers to exercise participation. Furthermore, awareness of the benefits of physical activity is not sufficient to promote exercise participation in persons with MS. Perceived exercise self-efficacy is shown to play an important role in promoting exercise participation in persons with MS.
Publisher: Georg Thieme Verlag KG
Date: 07-2007
Abstract: The purpose of this study was to determine if exercise-induced delayed onset muscle soreness (DOMS) would alter O2 uptake kinetics during heavy cycling in 9 untrained females. O2 uptake kinetics were characterised during 8-min of constant-load cycling performed with and without DOMS. DOMS was caused by completing 30 min of bench-stepping at a rate of 15 steps.min(-1). Two days after bench stepping, all subjects reported significant leg muscle soreness. Both phase II kinetics (without DOMS tau1: 26.6 +/- 2.4 s with DOMS tau1: 27.2 +/- 3.7 s) and the slow component litude (without DOMS: 277 +/- 15 mL.min(-1) with DOMS: 291 +/- 21 mL.min(-1)) were unaffected by DOMS. The change in blood lactate concentration from rest to end-exercise was significantly greater during exercise performed with DOMS. Eccentric exercise causing a moderate degree of DOMS does not appear to impact upon the mechanisms mediating phase II or the slow component of O2 uptake kinetics.
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 2021
Publisher: Informa UK Limited
Date: 23-08-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2016
Publisher: Clinical Exercise Physiology Association
Date: 03-2019
DOI: 10.31189/2165-6193-8.1.13
Abstract: Background: We sought to determine if women (65–74 y) can self-select an exercise intensity during walking commensurate with current physical activity recommendations. Methods: Thirteen healthy older women (age = 68 ± 3 y, body mass index = 25.7 ± 4.9 kg·m−2, peak O2 uptake = 24.1 ± 4.5 mL·kg−1·min−1) performed 4 30-min walking trials (2 × treadmill [TM], 2 × overground [OG]) in a counterbalanced, randomized order. For the first walking trials (i.e., TM1 and OG1), participants self-selected walking pace. Walking speed, heart rate (HR) and ratings of perceived exertion (RPE) were recorded. For the second trials for each mode (i.e., TM2 and OG2), walking speed was controlled to match speeds selected during TM1 and OG1, and pulmonary gas exchange, HR, and RPE were measured. Results: Exercise intensity was within current guidelines: OG = 70% HRpeak, 95% confidence interval (CI) = 61–75% TM = 66% HRpeak, 95% CI = 63–74%. Significant increases in HR and walking speed were observed during OG (HR P = 0.005, walking speed P = 0.001) compared with TM O2 uptake during OG was significantly greater than TM for first 15 min exercise. Conclusion: Healthy women can self-select intensity during walking commensurate with current physical activity recommendations.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.RESP.2010.06.018
Abstract: We examined the influence of operational lung volumes and mean inspiratory flow on the litude of the slow component of O₂uptake (V(O)₂(SC) ) during constant-load cycling performed below and above the respiratory compensation threshold (RCT) in young (24±1yr), healthy in iduals (n=10). Subjects demonstrated a significantly greater rise in expiratory reserve volume (ERV) and mean inspiratory flow over the V(O)₂(SC) period during exercise performed above compared with below the RCT (P<0.05). Inspiratory reserve volume (IRV) was, on average, smaller for trials performed above relative to below the RCT (P<0.05). The difference in the magnitudes of change in ERV and mean inspiratory flow, but not IRV, were positively correlated with the increase in V(O)₂(SC) litude between work rates (R(2)=0.86, P<0.01). These findings suggest that dynamic hyperinflation and mean inspiratory flow (by increasing inspiratory resistive work) contribute to the development of the V(O)₂(SC') , particularly when exercise is performed above the RCT.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2018
Publisher: American Physiological Society
Date: 2021
DOI: 10.1152/AJPHEART.00427.2020
Abstract: High-intensity endurance exercise elicits acute cardiac imbalances that may be an important stimulus for adaptive cardiac remodeling. This study highlights that following a bout of high-intensity exercise that is typical of routine day-to-day cycling training, exercise-induced autonomic, biochemical, and functional cardiac imbalances are attenuated in middle-aged relative to young well-trained cyclists. These findings suggest that aging may alter exercise-induced stress stimulus response that initiates cardiac remodeling in Athlete’s Heart.
Publisher: Springer Science and Business Media LLC
Date: 03-2016
DOI: 10.1007/S10554-016-0862-8
Abstract: Pulmonary hypertension (PH) is a progressively fatal disease having a significant impact on right ventricular (RV) function, a major determinant of long-term outcome in PH patients. In our clinic we frequently noticed the combination of PH and reduced RV function, but with discordant Tricuspid Annular Plane Systolic Excursion (TAPSE) values. The present study focuses on whether RV free wall strain measured using 2-dimensional speckle-tracking echocardiography is able to predict mortality in this subgroup of PH patients. 57 patients with PH and RV dysfunction (visual echocardiographic assessment of ≥2) and pseudo-normalized TAPSE values (defined as ≥16 mm) were retrospectively evaluated. Patients were ided by RV free -20 % as cut-off value. Follow-up data on all-cause mortality were registered after a median follow-up time of 27.9 ± 1.7 months. RV free of ≥-20 % was predictive of all-cause mortality after a median follow-up time of 27.9 ± 1.7 months (HR 3.76, 95 % CI 1.02-13.92, p = 0.05). RV free ≥-20 % remained a significant predictor of all-cause mortality (HR 4.30, 95 % CI 1.11-16.61, p = 0.04) after adjusting for PH-specific treatment. On the contrary, TAPSE was not a significant predictor of all-cause mortality. RV free wall strain provides prognostic information in patients with PH and RV dysfunction, but with normal TAPSE values. Future studies with larger cohorts, longer follow-up periods and inclusion of more echocardiographic parameters measuring LV and RV function could confirm the strength of RV free ≥-20 % as a predictor of mortality for this subgroup of patients with PH.
Publisher: Wiley
Date: 18-02-2016
DOI: 10.1113/JP271889
Publisher: American Physiological Society
Date: 10-2020
DOI: 10.1152/JAPPLPHYSIOL.00314.2020
Abstract: Variability in the performance responses following an overload training period and subsequent taper was associated with the variation in the muscle fiber typology of the gastrocnemius. Runners with an estimated higher proportion of type I fibers (i.e., lower carnosine z-score) were able to maintain performance in response to an overload training period and subsequently achieve a superior performance supercompensation. These findings show that muscle fiber typology contributes to the variability in performance responses following training.
Publisher: Springer Science and Business Media LLC
Date: 12-11-2019
DOI: 10.1007/S10554-019-01725-3
Abstract: Acute cellular rejection (ACR) remains a significant contributor to increased morbidity and mortality in heart transplant recipients. Early detection of ACR by non-invasive imaging is of potential clinical benefit. This study sought to investigate the use of non-invasive early global diastolic strain rate (GDSRe) and global longitudinal strain (GLS) in the detection of biopsy proven ACR. We retrospectively analysed 31 heart transplant patients (Mean age 52 ± 14 years) with biopsy proven ACR who underwent serial transthoracic echocardiographic examination and 2D strain analysis. Traditional echocardiographic systolic and diastolic parameters and novel systolic and diastolic strain imaging were measured during (1) early rejection free period (0R) (2) pre-rejection period (pre-1R) and (3) grade 1R acute cellular rejection (1R-ACR). GDSRe was significantly reduced (p = 0.0001) during the pre-rejection period (pre-1R) (0.74/s) when compared with 0R (0.97/s). GLS was only significantly reduced during 1R-ACR (17.7%), p = 0.001 but could not detect pre-1R (19.9%). Global diastolic strain rate at isovolumic relaxation showed no significant differences between any of the rejection periods. Traditional systolic and diastolic indices showed no significant differences. In conclusion, early global diastolic strain rate is the most sensitive parameter to detect subclinical myocardial dysfunction during early periods of pre-1R prior to biopsy confirmed 1R-ACR. GDSRe is a potential new tool for non-invasive screening of early post-transplant cardiac allograft rejection.
Publisher: Springer Science and Business Media LLC
Date: 12-11-2020
DOI: 10.1007/S10237-019-01252-Z
Abstract: Mechanical circulatory support device (MCS) design has improved over the years and yet blood damage (e.g., hemolysis) remains a problem. Accumulating evidence indicates a subhemolytic threshold for red blood cells (RBC)-a threshold at which RBC deformability is impaired prior to hemolysis. The current study aimed to assess the deformability of RBC exposed to supra-physiological shear stresses that are typical of MCS devices and assess whether a method used to estimate an in idualized subhemolytic threshold, accurately demarcates whether future application of shear stress was damaging. Suspensions of RBC were "conditioned" with discrete magnitudes of shear stress (5-100 Pa) for specific durations (1-16 s). Cellular deformability was subsequently measured via ektacytometry and a mechanical sensitivity (MS) index was calculated to identify the subhemolytic threshold. Thereafter, fresh RBC suspensions were exposed to a magnitude of shear stress 10 Pa above, 10 Pa below, or matched to a donor's previously estimated subhemolytic threshold for a given duration (1, 4, 16 s) to ascertain the sensitivity of the subhemolytic threshold. The MS index of RBC was significantly impaired following exposure to 10 Pa above the subhemolytic threshold (p < 0.0001), and significantly enhanced following exposure to 10 Pa below the subhemolytic threshold (p < 0.01). For all shear conditions, there was no significant increase in free hemoglobin. Functional assessments of RBC may be useful when conducting biocompatibility testing of MCS devices, to detect trauma to blood prior to overt cell rupture being induced.
Publisher: Springer International Publishing
Date: 2023
Publisher: Informa UK Limited
Date: 13-06-2021
DOI: 10.1080/17461391.2021.1933199
Abstract: The aim of this study was to determine the influence of training volume alterations on ersity and composition of the gut microbiome in a free-living cohort of middle-distance runners. Fourteen highly-trained middle-distance runners (
Publisher: Springer Science and Business Media LLC
Date: 07-02-2014
DOI: 10.1007/S00421-014-2832-Y
Abstract: To determine if gender and/or the use of oral contraceptives alter cycling performance with exercise-induced muscle damage (EiMD). Nine male adults (MEN), nine normally menstruating female adults (WomenNM), and nine female adults using oral contraceptives (WomenOC) participated. Gas exchange and time to exhaustion were measured during continuous cycling performed at three distinct power outputs before (pre) and 48 h after (post) 240 maximal effort eccentric contractions of the quadriceps muscles designed to induce muscle damage (i.e., EiMD). The change in muscle damage (i.e., range of motion about the knee joint and serum creatine kinase activity) from pre- compared to post-EiMD was greater in MEN and WomenOC compared to the WomenNM. Time to exhaustion decreased after EiMD in MEN (5.19 ± 4.58 min, p = 0.01) and in WomenOC (2.86 ± 2.83 min, p = 0.02) but did not change in WomenNM (0.98 ± 2.28 min, p = 0.43). Accordingly, the slow component of O2 uptake, expressed relative to time to exhaustion (i.e., % min(-1)), was greater in post- compared to pre-EiMD for MEN (p = 0.02) and the WomenOC (p = 0.03), but not for the WomenNM (p = 0.12). The preservation of exercise tolerance during heavy-intensity cycling performed after intense eccentric exercise is improved in women compared to men. Furthermore, the preservation of exercise tolerance is exclusive to 17β-estradiol and cannot be replicated with an exogenous synthetic estrogen replacement delivered in an oral contraceptive.
Publisher: Longdom Group
Date: 2014
Publisher: Cold Spring Harbor Laboratory
Date: 28-04-2023
DOI: 10.1101/2023.04.26.538396
Abstract: People with Multiple Sclerosis typically exhibit greater levels of exercise-induced fatigue compared to healthy in iduals. However, it is unknown if voluntary muscle activation is affected over a range of contraction forces in people with MS who have exercise-induced fatigue. The purpose of this study was to use transcranial magnetic stimulation (TMS) and electrical muscle stimulation to examine muscle activation during exercise-induced fatigue. Ten people with relapsing-remitting MS (39 ± 7 years) and 10 healthy controls (40 ± 5 years) performed elbow flexions at 25%, 50%, 75%, 90%, and 100% MVC while electromyography (EMG) of the biceps brachii was recorded. Sustained elbow flexion MVCs were then performed until force declined to 60% of baseline MVC, and the target contraction intensities of 25%, 50%, 75%, 90%, and 100% MVC were examined again. The Fatigue Severity Scale was higher for the MS group ( P 0.01). Exercise-induced fatigue caused a reduction in biceps EMG litude for the MS group across all contraction intensities ( P 0.01), which was not aligned with changes in MEP litude ( P = 0.25). Exercise-induced fatigue reduced motor cortical voluntary activation in the MS group across all contraction intensities ( P 0.01), as well as increased MS time-to-peak force ( P 0.01) and half relaxation time for TMS evoked twitches ( P = 0.03). These findings provide evidence that MS-related fatigability during maximal contractions is due to the inability for the motor cortex to drive the muscle, with possible contributions from altered contractile properties in the MS muscle. We use transcranial magnetic stimulation to demonstrate that people with relapsing-remitting Multiple Sclerosis (MS) have a reduced ability to activate muscle following maximal effort fatiguing contractions. Although our MS participants reported greater symptoms of fatigue via the Fatigue Severity Scale, their reduced ability to activate muscle was more associated with the duration of disease.
Publisher: Springer Science and Business Media LLC
Date: 08-08-2022
DOI: 10.1007/S10554-022-02586-Z
Abstract: Two-dimensional (2D) strain analysis is a sensitive method for detecting myocardial dysfunction in acute cellular rejection (ACR) from post-transplant complications. This study aims to evaluate the utility of novel left (LV) and right ventricular (RV) strain parameters for prognostic risk stratification associated with ACR burden at 1-year post transplantation. 128 Heart transplant patients, assessed between 2012 and 2018, underwent transthoracic echocardiography and endomyocardial biopsy. 2D strain analysis was performed and history of rejection burden was assessed and grouped according to ACR burden at 1-year post transplantation. The primary endpoint was all-cause mortality at 6-years follow up. 21 patients met primary the endpoint. Multivariate analysis of 6-year all-cause mortality showed LV global longitudinal strain (LV GLS) (Hazard Ratio [HR] = 1.21, CI = 1.06–1.49), LV early diastolic strain rate (LV ESr) (HR = 1.31, CI = 1.12–1.54), RV GLS (HR = 1.12, CI = 1.02–1.25) and RV ESr (HR = 1.26, CI = 1.12–1.47) were significant predictors of outcome. Univariate analysis also showed LV GLS, LV ESr, RV GLS and RV ESr were significant predictors of outcome. Optimal cut-off for predicting 6-year mortality for LV GLS by receive operator characteristic was 15.5% (sensitivity: 92%, specificity: 79%). Significant reductions (p 0.05) in LV GLS, RV GLS and LV and RV ESr between rejection groups were seen. Non-invasive LV and RV strain parameters are predictors of mortality in post-transplant patient with ACR. LV GLS and LV ESr are superior to other strain and conventional echo parameters.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2014
Publisher: Informa UK Limited
Date: 2006
Publisher: SPIE
Date: 17-02-2017
DOI: 10.1117/12.2253585
Publisher: Wiley
Date: 15-12-2010
DOI: 10.1113/EXPPHYSIOL.2009.048975
Abstract: The contribution of respiratory muscle O2 uptake ((.)V(O2RM)) to the development of the slow component of O2 uptake kinetics ((.)V(O2SC)) is unclear. The aim of the present study was to examine the impact of respiratory muscle unloading (via breathing, a He-O2 mixture) on the litude of (.)V(O2SC) during exercise performed below (B-RCT) and above the respiratory compensation threshold (A-RCT). We hypothesized that breathing He-O2 would reduce the litude of the (.)V(O2SC) by a greater amount during exercise performed A-RCT than B-RCT. Eight healthy male recreational cyclists performed constant load cycling in four sets of conditions: (1) B-RCT breathing normal air (2) B-RCT breathing He-O2 (3) A-RCT breathing normal air and (4) A-RCT breathing He-O2. Breathing He-O2 did not significantly attenuate the (.)V(O2SC) during exercise performed B-RCT (-3+/-14%, P >0.05). However, breathing He-O2 significantly reduced the (.)V(O2SC) during exercise A-RCT(-45+/-6%, P <0.05). The attenuated (.)V(O2SC) while breathing He-O2 is likely to reflect a decreased (.)V(O2RM). Minute ventilation was not +/-different between normal air and He-O2 breathing trials either B-RCT or A-RCT. However, operating lung volume was significantly lower when breathing He-O2 during exercise performed A-RCT (-12+/-3%, P <0.05). These findings suggest that (.)V(O2RM) comprises a greater proportion of the (.)V(O2SC) when exercise is performed A-RCT compared with B-RCT. Therefore, the impact of breathing He-O2 was more pronounced during exercise A-RCT. Furthermore, changes in operating lung volume and the work of breathing appear to play an important role in the development of the (.)V(O2SC).
Publisher: Springer Science and Business Media LLC
Date: 12-08-0008
DOI: 10.1007/S00421-013-2742-4
Abstract: Although markers of myocyte injury, electrolyte disturbances and an autonomic imbalance have been reported following exercise, the effect of prolonged strenuous activity on cardiac electrical conduction is not well understood. This study examined atrial and ventricular conduction dynamics during recovery from exercise. Electrocardiographic intervals were obtained from eight highly-trained males before, during recovery (15, 30, 45 and 60 min post-exercise) and 24 h after a prolonged bout of strenuous exercise. Time-domain, frequency-domain and non-linear analyses of the RR, PR and QT intervals were analysed to investigate the effect of exercise on autonomic modulation and cardiac electrical conduction. Serum electrolyte and high-sensitivity cardiac troponin T (hs-cTnT) concentrations were measured before exercise, and after 60 min and 24 h of recovery. The root mean square of the successive differences of RR, PR and QT intervals was significantly reduced during recovery (p < 0.05). Normalised low- and high-frequency power of RR intervals significantly increased and decreased, respectively, during recovery. Approximate entropy of PR and QT intervals, and the QT-variability index significantly increased during recovery. All measures except mean QT interval (pre 422 ± 10 ms vs 24 h post 442 ± 11 ms, p = 0.013) returned to pre-exercise values after 24 h. Serum hs-cTnT was significantly elevated 60 min after exercise (pre 5.2 ± 0.7 ng L(-1) vs 60 min post 27.4 ± 6.2 ng L(-1), p = 0.01) and correlated with exercising heart rate (R(2) = 0.89, p 0.05). The results suggest suppressed parasympathetic and/or sustained sympathetic modulation of heart rate during recovery, concomitant with perturbations in atrial and ventricular conduction dynamics. Exercise-induced hs-cTnT release was heart rate dependent.
Publisher: European Respiratory Society (ERS)
Date: 27-10-2012
Location: Portugal
No related grants have been discovered for Surendran Sabapathy.