ORCID Profile
0000-0001-6114-1649
Current Organisations
The University of Edinburgh
,
University of Bristol
,
University of Central Florida
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Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2012
Publisher: Canadian Science Publishing
Date: 2014
Abstract: β-Alanine (BA) has been linked with oxidative protection. This study evaluated antioxidant properties of BA. Twenty-five men consumed BA or placebo for 4 weeks, and completed a 40-min run to induce oxidative stress. Blood draws were taken to measure 8-isoprostane, total antioxidant capacity, superoxide dismutase, and glutathione. BA had no significant influence on reducing exercise-induced oxidative stress. Confidence intervals suggest a reduction in lipid peroxidation. BA supplementation may have little influence as an antioxidant.
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.EXGER.2013.10.005
Abstract: The purpose of this investigation was to determine body composition classification using field-based testing measurements in healthy elderly men and women. The use of isoperformance curves is presented as a method for this determination. Baseline values from 107 healthy Caucasian men and women, over the age of 65years old, who participated in a separate longitudinal study, were used for this investigation. Field-based measurements of age, height, weight, body mass index (BMI), and handgrip strength were recorded on an in idual basis. Relative skeletal muscle index (RSMI) and body fat percentage (FAT%) were determined by dual-energy X-ray absorptiometry (DXA) for each participant. Sarcopenia cut-off values for RSMI of 7.26kg·m(-2) for men and 5.45kg·m(-2) for women and elderly obesity cut-off values for FAT% of 27% for men and 38% for women were used. In iduals above the RSMI cut-off and below the FAT% cut-off were classified in the normal phenotype category, while in iduals below the RSMI cut-off and above the FAT% cut-off were classified in the sarcopenic-obese phenotype category. Prediction equations for RSMI and FAT% from sex, BMI, and handgrip strength values were developed using multiple regression analysis. The prediction equations were validated using double cross-validation. The final regression equation developed to predict FAT% from sex, BMI, and handgrip strength resulted in a strong relationship (adjusted R(2)=0.741) to DXA values with a low standard error of the estimate (SEE=3.994%). The final regression equation developed to predict RSMI from the field-based testing measures also resulted in a strong relationship (adjusted R(2)=0.841) to DXA values with a low standard error of the estimate (SEE=0.544kg·m(-2)). Isoperformance curves were developed from the relationship between BMI and handgrip strength for men and women with the aforementioned clinical phenotype classification criteria. These visual representations were used to aid in the classification and evaluation of sarcopenia, obesity, and sarcopenic-obesity in elderly in iduals. Future research should replicate the current findings with an increased s le size and the development of tailored interventions for each body composition category.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2010
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2013
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.EXGER.2013.08.007
Abstract: Evidence suggests CaHMB may impact muscle mass and/or strength in older adults, yet no long-term studies have compared its effectiveness in sedentary and resistance training conditions. The purpose of this study was to evaluate the effects of 24 weeks of CaHMB supplementation and resistance training (3 d wk(-1)) or CaHMB supplementation only in ≥65 yr old adults. This double-blinded, placebo-controlled, trial occurred in two phases under ad libitum conditions. Phase I consisted of two non-exercise groups: (a) placebo and (b) 3 g CaHMB consumed twice daily. Phase II consisted of two resistance exercise groups: (a) placebo and resistance exercise and (b) 3 g CaHMB consumed twice daily and resistance exercise (RE). Strength and functionality were assessed in both phases with isokinetic leg extension and flexion at 60°·s(-1) and 180°·s(-1) (LE60, LF60, LE180, LF180), hand grip strength (HG) and get-up-and-go (GUG). Dual X-Ray Absorptiometry (DXA) was used to measure arm, leg, and total body lean mass (LM) as well as total fat mass (FM). Muscle Quality was measured for arm (MQ(HG)=HG/arm LM) and Leg (MQ60=LE60/leg LM) (MQ180=LE180/leg LM). At 24 weeks of Phase I, change in LE60 (+8.8%) and MQ180 (+20.8%) for CaHMB was significantly (p<0.05) greater than that for placebo group. Additionally, only CaHMB showed significant (p<0.05) improvements in total LM (2.2%), leg LM (2.1%), and LE180 (+17.3%), though no treatment effect was observed. Phase II demonstrated that RE significantly improved total LM (4.3%), LE60 (22.8%), LE180 (21.4%), HG (9.8%), and GUG (10.2%) with no difference between treatment groups. At week 24, only CaHMB group significantly improved FM (-3.8%) and MQHG (7.3%) however there was no treatment main effect for these variables. CaHMB improved strength and MQ without RE. Further, RE is an effective intervention for improving all measures of body composition and functionality.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2010
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2010
Publisher: IOP Publishing
Date: 17-12-2013
DOI: 10.1088/0967-3334/35/1/31
Abstract: The purpose of this study was to examine the validity and reliability of estimated parameters of the work-time relationship during cross-country ski ergometry using the traditional multi-trial critical power (CP) test and a 3 min 'all-out' test (3MT). Fourteen recreationally active male participants (mean ± SD age: 22.14 ± 2.85 yrs height: 177.09 ± 6.57 cm weight: 85.68 ± 13.56 kg) completed three testing visits. All testing was conducted using an upper-body ergometer (SkiErg, Concept2, Inc., Morrisville, VT). A graded exercise test was used to determined maximal oxygen uptake (VO2peak). Two separate 3MT sessions were used to determine oxygen uptake (VO23MT), end-test power (EP), work above end-test power (WEP) and end stroke rate (ESR). Additionally, three time trials completed in a single day at simulated distances of 300 m, 650 m and 1000 m were used to estimate CP, W' and critical stroke rate (CSR). VO2peak (3.65 ± 0.50 l · min(-1)) and VO23MT (3.59 ± 0.4 l · min(-1)) were not significantly different (p = 0.162). Intraclass correlation coefficients for EP, WEP and ESR were 0.809, 0.611 and 0.783, respectively. EP (148 ± 33 W) and CP (157 ± 49 W), were not significantly different between the testing methodologies (p = 0.290) and were highly correlated (r = 0.780). WEP (8.4 ± 3.0 kJ) and W' (8.3 ± 3.0 kJ) were similar (p = 0.947) but not related (r = 0.119), while ESR (45 ± 7 spm) and CSR (47 ± 7 spm) values were not significantly different (p = 0.238) and moderately correlated (r = 0.498). The 3MT using ski ergometry was shown to produce concurrently valid results with the traditional multi-trial CP test for CP and CSR, but not W', and elicited similar maximal oxygen uptake values when compared to a graded exercise test.
Publisher: Oxford University Press (OUP)
Date: 02-2012
DOI: 10.7205/MILMED-D-11-00198
Abstract: The purpose of this study was to evaluate the use of critical velocity (CV) and isoperformance curves as an alternative to the Army Physical Fitness Test (APFT) two-mile running test. Seventy-eight men and women (mean +/- SE age: 22.1 +/- 0.34 years VO2(MAX): 46.1 +/- 0.82 mL/kg/min) volunteered to participate in this study. A VO2(MAX) test and four treadmill running bouts to exhaustion at varying intensities were completed. The relationship between total distance and time-to-exhaustion was tracked for each exhaustive run to determine CV and anaerobic running capacity. A VO2(MAX) prediction equation (Coefficient of determination: 0.805 Standard error of the estimate: 3.2377 mL/kg/min) was developed using these variables. Isoperformance curves were constructed for men and women to correspond with two-mile run times from APFT standards. In idual CV and anaerobic running capacity values were plotted and compared to isoperformance curves for APFT 2-mile run scores. Fifty-four in iduals were determined to receive passing scores from this assessment. Physiological profiles identified from this procedure can be used to assess specific aerobic or anaerobic training needs. With the use of time-to-exhaustion as opposed to a time-trial format used in the two-mile run test, pacing strategies may be limited. The combination of variables from the CV test and isoperformance curves provides an alternative to standardized time-trial testing.
Publisher: Springer Science and Business Media LLC
Date: 13-03-2012
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2011
Publisher: Springer Science and Business Media LLC
Date: 20-11-2011
DOI: 10.1007/S00726-011-1158-X
Abstract: The purpose of this study was to evaluate the effects of β-alanine supplementation on markers of oxidative stress. Twenty-four women (age: 21.7±2.1 years VO2max: 2.6±0.3 l min(-1)) were randomly assigned, in a double-blind fashion, to a β-alanine (BA, 2×800 mg tablets, 3× daily CarnoSyn® n=13) or placebo (PL, 2×800 mg maltodextrin tablets, 3× daily n=11) group. A graded oxygen consumption test (VO2max) was performed to evaluate VO2max, time to exhaustion, ventilatory threshold and establish peak velocity (PV). A 40-min treadmill run was used to induce oxidative stress. Total antioxidant capacity, superoxide dismutase, 8-isoprostane (8ISO) and reduced glutathione were measured. Heart rate and ratings of perceived exertion were recorded during the 40 min run. Separate three- [4×2×2 acute (base vs. IP vs. 2 vs. 4 h)×chronic (pre- vs. post-)×treatment (BA vs. PL)] and two- [2×2 time (pre-supplement vs. post-supplement)×treatment (BA vs. PL)] way ANOVAs were used for analyses. There was a significant increase in VO2max (p=0.009), independent of treatment, with no significant changes in TTE (p=0.074) or VT (p=0.344). Ratings of perceived exertion values were significantly improved from pre- to post-supplementation for the BA group only at 40 min (p=0.02). The ANOVA model demonstrated no significant treatment effects on oxidative stress. The chronic effects of BA supplementation demonstrated little antioxidant potential, in women, and little influence on aerobic performance assessments.
Publisher: Cold Spring Harbor Laboratory
Date: 07-2023
DOI: 10.1101/2023.06.29.23292056
Abstract: Infections can lead to persistent or long-term symptoms and diseases such as shingles after varicella zoster, cancers after human papillomavirus, or rheumatic fever after streptococcal infections 1, 2 . Similarly, infection by SARS-CoV-2 can result in Long COVID, a condition characterized by symptoms of fatigue and pulmonary and cognitive dysfunction 3–5 . The biological mechanisms that contribute to the development of Long COVID remain to be clarified. We leveraged the COVID-19 Host Genetics Initiative 6, 7 to perform a genome-wide association study for Long COVID including up to 6,450 Long COVID cases and 1,093,995 population controls from 24 studies across 16 countries. We identified the first genome-wide significant association for Long COVID at the FOXP4 locus. FOXP4 has been previously associated with COVID-19 severity 6 , lung function 8 , and cancers 9 , suggesting a broader role for lung function in the pathophysiology of Long COVID. While we identify COVID-19 severity as a causal risk factor for Long COVID, the impact of the genetic risk factor located in the FOXP4 locus could not be solely explained by its association to severe COVID-19. Our findings further support the role of pulmonary dysfunction and COVID-19 severity in the development of Long COVID.
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.EXGER.2015.12.002
Abstract: Raw bioelectrical impedance analysis (BIA) data [resistance (R) reactance (Xc)] through bioelectrical impedance vector analysis (BIVA) and phase angle (PhA) have been used to evaluate cellular function and hydration status. The purpose of this investigation was to examine the effects of resistance training (RT) on classic and specific BIVA in elderly women. Twenty women (mean ± SD age: 71.9 ± 6.9 years BMI: 24.5 ± 3.0 kg m(-2)) completed a 6-month RT program. Whole-body, single-frequency BIA, body geometry, and leg strength (5RM) measures were completed at baseline (t0), 3 months (t3), and 6 months (t6). The mean impedance vector displacements were compared using Hotelling's T(2) test to evaluate changes in R and Xc relative to height (R/ht Xc/ht) or body volume (Rsp Xcsp) estimated from the arms, legs, and trunk. 5RM, PhA, and BIVA variables were compared using ANOVA. PhA improved at t6 (p < 0.01), while 5RM improved at t3 and t6 (p < 0.01). Using classic BIVA, 6 months (T(2) = 31.6 p < 0.01), but not 3 months of RT (T(2) = 4.5 p = 0.20), resulted in significant vector migration. Using specific BIVA, 6 months (T(2) = 24.4 p < 0.01), but not 3 months of RT (T(2) = 5.5 p = 0.10), also resulted in significant vector migration. 5RM was correlated to both PhA (r = 0.48-56) and Xcsp (r = 0.45-53) at all time points. Vector displacements were likely the result of improved cellular integrity (Xcsp) and cellular health (PhA).
Publisher: Springer Science and Business Media LLC
Date: 17-07-2011
DOI: 10.1007/S00421-011-2076-Z
Abstract: The purpose of this study was to examine the reliability of the intermittent critical velocity (ICV) test and assess critical rest interval (CRI) during repeated-sprint exercise. The ICV test is used to examine the linear relationship between total distance and time-to-exhaustion during interval exercise, yielding a repeatable, moderate-intensity parameter (ICV), a high-intensity exhaustive parameter (W'), and CRI. CRI is the theoretical rest period needed to complete a series of repeated bouts of exercise without fatigue. Twenty-four healthy college-aged men (mean ± SD age 22.7 ± 2.9 years weight 85.8 ± 15.3 kg VO(2max) 50.7 ± 8.8 ml/kg/min) and women (mean ± SD age 21.4 ± 2.3 years weight 58.9 ± 5.2 kg VO(2max) 46.4 ± 4.4 ml/kg/min) participants completed two ICV tests (T1 and T2), using 10 s repeated sprints to exhaustion during separate sessions of treadmill running. Linear regression was used to determine ICV and W', while CRI was calculated using the relationship between the number of intervals completed and a variant of ICV. Intraclass correlation coefficients (ICCs) for ICV, W', and CRI were 0.89 (T1 4.42 ± 0.55 m/s T2 4.34 ± 0.67 m/s), 0.80 (T1 125.6 ± 62.7 m T2 144.6 ± 65.4 m), and 0.59 (T1 23.9 ± 2.0 s T2 24.5 ± 2.6 s), respectively. These moderate to high ICC values indicate reliable measurements between ICV trials. Additionally, the evaluation of CRI demonstrated the attainment of a steady-state heart rate (94% of maximum) during a separate session of repeated supramaximal treadmill sprints. The ICV test during treadmill running provides reliable ICV and W' measures, as well as an estimated recovery time via CRI for men and women.
Publisher: Canadian Science Publishing
Date: 10-2010
DOI: 10.1139/H10-056
Abstract: The aim of this study was to evaluate the combined effects of a 10-week exercise program with ingestion of caffeine and epigallocatechin-3-gallate (EGCG) on body composition, cardiovascular fitness, and strength in overweight and obese women. In a double-blind, placebo-controlled approach, overweight and obese women (n = 27) were randomly assigned to treatment groups with exercise (an active-supplementing group with exercise (EX-Act) and a placebo group with exercise (EX-PL)) or without exercise (an active-supplementing group without exercise (NEX-Act) and a placebo group without exercise (NEX-PL)). All participants consumed 1 drink per day for 10 weeks EX-Act and EX-PL participated in a concurrent endurance and resistance training program. Changes in body composition were assessed using a 4-compartment model. Changes in muscle mass (MM) were evaluated using a DXA-derived appendicular lean–soft tissue equation. There was a significant time × treatment interaction for MM (p = 0.026) and total cholesterol (TC) (p = 0.047), and a significant time × training interaction for peak oxygen consumption (p = 0.046) and upper-body and lower-body strength (p 0.05). Significant differences between the EX groups and NEX groups for percentage change in MM and peak oxygen consumption, and upper-body and lower-body strength, were revealed. Clinical markers for hepatic and renal function revealed no adverse effects. TC significantly decreased for the active-supplementing groups (EX-Act, NEX-Act). The current study suggests that implementing a caffeine–EGCG-containing drink prior to exercise may improve MM, fitness, and lipid profiles in overweight women.
Publisher: Springer Science and Business Media LLC
Date: 21-10-2010
DOI: 10.1007/S00421-010-1683-4
Abstract: The purpose of this study was to propose a systematic method for the identification of training strategies and team selection using isoperformance curves. Rowing is a sport that relies on both aerobic and anaerobic energy contributions during a standard 2,000 m competition. The critical velocity model combines both aerobic (critical velocity, CV) and anaerobic (anaerobic rowing capacity, ARC) parameters in a single two-dimensional graphic display. The concept of isoperformance curves, a series of linear equations corresponding to minimum performance standards, allows for an objective overview of a large group of athletes of varying talent. The purpose of this study was to develop physiological profiles from the CV test, and to evaluate results with isoperformance curves to identify training strategies for collegiate rowers. Thirty-five female collegiate rowers completed four time trials over various distances (400, 600, 800, and 1,000 m). CV and ARC were calculated and compared between novice and varsity athletes. CV values for the varsity group were significantly higher than the novice group (P = 0.016). No significant differences were found between groups for ARC (P = 0.068). Mean and in idual CV and ARC values were plotted on the x- and y-axes, respectively, and junior, collegiate, and elite isoperformance curves were developed using 2,000 m times from recent indoor rowing competitions. Stratification of athletes through isoperformance curves was used to identify specific training interventions (anaerobic and/or aerobic) needed to improve their 2,000 m performance. The information drawn from isoperformance curves and the parameters of the CV test can be used to provide an objective view of physiological capabilities and training needs on both an in idual and team basis.
Publisher: Informa UK Limited
Date: 02-01-2021
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.EXGER.2015.02.012
Abstract: The effects of 12-weeks of HMB ingestion and resistance training (RT) on abdominal adiposity were examined in 48 men (66-78 yrs). All participants were randomly assigned to 1 of 4 groups: no-training placebo (NT-PL), HMB only (NT-HMB), RT with PL (RT-PL), or HMB with RT (RT-HMB). DXA was used to estimate abdominal fat mass (AFM) by placing the region of interest over the L1-L4 region of the spine. Outcomes were assessed by ANCOVA, with Bonferroni-corrected pairwise comparisons. Baseline AFM values were used as the covariate. The ANCOVA indicated a significant difference (p = 0.013) between group means for the adjusted posttest AFM values (mean (kg) ± SE: NT-PL = 2.59 ± 0.06 NT-HMB = 2.59 ± 0.61 RT-PL = 2.59 ± 0.62 RT-HMB = 2.34 ± 0.61). The pairwise comparisons indicated that AFM following the intervention period in the RT-HMB group was significantly less than NT-PL (p = 0.013), NT-HMB (p = 0.011), and RT-PL (p = 0.010). These data suggested that HMB in combination with 12 weeks of RT decreased AFM in elderly men.
Publisher: Informa UK Limited
Date: 09-05-2016
DOI: 10.1080/02640414.2016.1183802
Abstract: The purpose of this study was to investigate the accuracy of fat-free mass (FFM) estimates from two-compartment (2C) models including air displacement plethysmography (ADP), ultrasound (US), near-infrared interactance (NIR), and the Jackson and Pollock skinfold equation (SKF) against a criterion four-compartment (4C) model in elite male rowers. Twenty-three elite-level male rowers (mean± SD age 24.6 ± 2.2 years stature: 191.4 ± 7.2 cm mass: 87.2 ± 11.2 kg) participated in this investigation. All body composition assessments were performed on the same day in random order, except for hydrostatic weighing (HW), which was measured last. FFM was evaluated using a 4C model, which included total body water from bioimpedance spectroscopy, body volume from HW, and total body bone mineral via dual-energy X-ray absorptiometry. The major findings of the study were that the 2C models evaluated overestimated FFM and should be considered with caution for the assessment of FFM in elite male rowers. Future studies should use multiple-compartment models, with measurement of TBW and bone mineral content, for the estimation of FFM.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.NUTRES.2010.09.004
Abstract: Preexercise nutritional investigations have recently become a popular avenue of examining the interaction of multiple ingredients on exercise and training methods. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion (TTE), yielding aerobic (CV) and anaerobic parameters (anaerobic running capacity [ARC]). The purpose of this study was to examine the hypothesis that a preexercise supplement containing caffeine, creatine, and amino acids (Game Time Corr-Jen Laboratories Inc, Aurora, CO) would positively impact CV and ARC in college-aged men and women. In a single-blind crossover design, 10 participants consumed the preexercise supplement (ACT) or placebo (PL) before each testing session. Each participant completed runs to exhaustion on a treadmill at 110%, 90% (day 1), and 105% and 100% (day 2) of the peak velocity (PV) determined from a graded exercise test. The ACT elicited a 10.8% higher ARC (P = .02) compared with the PL, whereas no difference was found in CV (0.6%, P = .38). The TTE was greater for the ACT than the PL at 110% (ACT = 125.7 ± 9.6 seconds, PL = 117.3 ± 12.6 seconds), 105% (ACT = 156.9 ± 11.0 seconds, PL = 143.8 ± 12.9 seconds), and 100% PV (ACT = 185.7 ± 10.7 seconds, PL = 169.7 ± 12.8 seconds) (P = .01-.04) but there was no difference for the TTE at 90% PV (ACT = 353.5 ± 52.7 seconds, PL = 332.7 ± 54.0 seconds) (P = .08). These findings suggest that the acute ingestion of this preexercise supplement may be an effective strategy for improving anaerobic performance, but appears to have no effect on aerobic power.
Publisher: Springer Science and Business Media LLC
Date: 02-11-2020
DOI: 10.1186/S12916-020-01766-9
Abstract: Pre-ecl sia is a leading cause of maternal and perinatal mortality and morbidity. Early identification of women at risk during pregnancy is required to plan management. Although there are many published prediction models for pre-ecl sia, few have been validated in external data. Our objective was to externally validate published prediction models for pre-ecl sia using in idual participant data (IPD) from UK studies, to evaluate whether any of the models can accurately predict the condition when used within the UK healthcare setting. IPD from 11 UK cohort studies (217,415 pregnant women) within the International Prediction of Pregnancy Complications (IPPIC) pre-ecl sia network contributed to external validation of published prediction models, identified by systematic review. Cohorts that measured all predictor variables in at least one of the identified models and reported pre-ecl sia as an outcome were included for validation. We reported the model predictive performance as discrimination ( C -statistic), calibration (calibration plots, calibration slope, calibration-in-the-large), and net benefit. Performance measures were estimated separately in each available study and then, where possible, combined across studies in a random-effects meta-analysis. Of 131 published models, 67 provided the full model equation and 24 could be validated in 11 UK cohorts. Most of the models showed modest discrimination with summary C -statistics between 0.6 and 0.7. The calibration of the predicted compared to observed risk was generally poor for most models with observed calibration slopes less than 1, indicating that predictions were generally too extreme, although confidence intervals were wide. There was large between-study heterogeneity in each model’s calibration-in-the-large, suggesting poor calibration of the predicted overall risk across populations. In a subset of models, the net benefit of using the models to inform clinical decisions appeared small and limited to probability thresholds between 5 and 7%. The evaluated models had modest predictive performance, with key limitations such as poor calibration (likely due to overfitting in the original development datasets), substantial heterogeneity, and small net benefit across settings. The evidence to support the use of these prediction models for pre-ecl sia in clinical decision-making is limited. Any models that we could not validate should be examined in terms of their predictive performance, net benefit, and heterogeneity across multiple UK settings before consideration for use in practice. PROSPERO ID: CRD42015029349 .
Publisher: IOP Publishing
Date: 25-02-2011
DOI: 10.1088/0967-3334/32/4/004
Abstract: This study was designed to compare critical velocity (CV) and anaerobic running capacity (ARC) estimates using the criterion method of four runs with two and three combination bouts to reduce the time and energy demands of the subjects. Twenty-eight men and women (mean ± SD age = 21.9 ± 3.0 years stature = 171.7 ± 9.7 cm body mass = 69.7 ± 13.4 kg) performed an incremental test to exhaustion to determine peak velocity (PV) at maximal oxygen consumption (VO(2)max). Four high-speed runs to exhaustion were conducted on separate days with 110% PV, 90% PV (day 1), 100% PV and 105% PV (day 2). The distances achieved were plotted over the times to exhaustion. Linear regression was used to determine the slopes (CV) and y-intercepts (ARC) using four velocities and the other ten possible velocity combinations. Two runs to exhaustion, at 90% PV and 110% PV, produced similar CV and ARC results to the standard four bouts (ICC = 0.995, SEM = 0.298). Three velocities at 90% PV, 100% PV and 110% PV also resulted in no differences from the criterion method (ICC = 0.999, SEM = 0.075). These results suggest that CV and ARC can be estimated from two velocities, but to ensure a linear relationship, three velocities are recommended.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2012
Publisher: Cambridge University Press (CUP)
Date: 12-07-2010
DOI: 10.1017/S0007114510002254
Abstract: Bioimpedance spectroscopy (BIS) has been used to track changes in total body water (TBW). Accurate TBW estimations can be influenced by both methodological and biological factors. One methodological variation that contributes to BIS TBW errors is the electrode placement. The purpose of the present study was to compare the reproducibility and validity of fixed-distance electrode placements (5 cm) with the standard single-site electrode placements. Twenty-nine subjects (fifteen men and fourteen women) participated in the reproducibility study, while sixty-nine subjects (thirty-three men and thirty-six women) participated in the validity study. The reproducibility study included two measurements that were taken 24 h apart, while the validity study consisted of a 12-week exercise intervention with measurements taken at weeks 1 and 12. TBW was estimated using BIS and 2 H techniques. Reproducibility results indicated that fixed-distance electrodes reduced the day-to-day standard error of the measurement in men (from 1·13 to 0·81 litres) but not in women (0·47 litres). sem values were lower for women than for men, suggesting that BIS TBW estimates are sex dependent. Validity results produced similar accurate findings (mean difference 0·21 litres). However, fixed-distance electrodes improved delta TBW errors (mean difference improvements ·04 litres in men, women, and men and women combined). When tracking changes in TBW, fixed-distance electrodes may reduce reproducibility errors and allow for smaller changes to be detected. However, the reduction of reproducibility errors may be greater for men than for women. Therefore, reproducibility calculations should be based on the sex of the s le population.
Publisher: Springer Science and Business Media LLC
Date: 2013
Abstract: To compare single estimations of fat-free mass (FFM) and to track FFM using single-frequency bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) compared with a four-compartment (4C) model in healthy elderly Americans. Thirty-four men and thirty-eight women (Caucasian, ≥ 65 years) were included in the study. Subjects participated in either the control group or the exercise group. All testing and training took place during the 21-week investigation. Body composition assessments using nine BIA equations, DXA and a 4C model were performed during weeks 1, 12 and 24 of the study. Single estimations for DXA and BIA produced high r values (0.79-0.95) and low standard error of estimate values (1.62-3.3 kg), producing subjective ratings of 'ideal' for men and 'excellent' for women. Both DXA and two BIA equations revealed the same significance when comparing groups and times with the 4C model. In idual accuracy for tracking changes was similar among BIA equations and DXA compared with the 4C model, with a total agreement of 25% for BIA and 27% for DXA compared with the 4C model. The current data in combination with the reliability errors for both BIA and DXA FFM estimations suggest that in idual results should be interpreted with caution if FFM changes are <5 kg. However, DXA and BIA are both valid methods that can be used interchangeably to estimate FFM at a single time point or for tracking changes in FFM in small groups (15-22) of healthy American older adults.
Publisher: Informa UK Limited
Date: 06-10-2016
DOI: 10.1080/07315724.2016.1140094
Abstract: The objective of this study was to compare the chronic effects of different whey protein forms on body composition and performance when supplemented with resistance training. Resistance-trained men (N = 56, 21.4 ± 0.4 years, 79.5 ± 1.0 kg) participated in an 8-week resistance training regimen (2 upper-body sessions and 2 lower-body sessions per week) and received one of 4 double-blinded treatments: 30 g/serving carbohydrate placebo (PLA) or 30 g/serving protein from either (a) 80% whey protein concentrate (WPC), (b) high-lactoferrin-containing WPC (WPC-L), or (c) extensively hydrolyzed WPC (WPH). All subjects consumed 2 servings of treatment per day specifically, once immediately before and after training and between meals on nontraining days. Blood collection, one repetition maximum (1RM) testing for bench press and hack squat, and body composition assessment using dual-energy x-ray absorptiometry (DXA) occurred prior to training and 48 hours following the last training session. Total body skeletal muscle mass increased in all groups (p < 0.0125). There were similar between-group increases in upper-body (4%-7%, analysis of covariance [ANCOVA] interaction p = 0.73) and lower-body (24%-35%, ANCOVA interaction p = 0.85) 1RM strength following the intervention. Remarkably, WPH reduced fat mass (-6%), which was significantly different from PLA (+4.4%, p < 0.0125). No time or between-group differences were present for serum markers of health, metabolism, or muscle damage, with the exception of blood urea nitrogen being significantly lower for WPH than WPC (p < 0.05) following the intervention. WPH may augment fat loss but did not provide any other advantages when used in combination with resistance training. More mechanistic research is needed to examine how WPH affects adipose tissue physiology.
Publisher: Georg Thieme Verlag KG
Date: 30-11-2011
Abstract: This study evaluated the effects of creatine (Cr) loading and sex differences on aerobic running performance. 27 men (mean±SD age: 22.2±3.1 years, ht: 179.5±8.7 cm, wt: 78.0±9.8 kg) and 28 women (age: 21.2±2.1 years, ht: 166.0±5.8 cm, wt: 63.4±8.9 kg) were randomly assigned to either creatine (Cr, di-creatine citrate n=27) or a placebo (PL n=28) group, ingesting 1 packet 4 times daily (total of 20 g/day) for 5 days. Aerobic power (maximal oxygen consumption: VO2max) was assessed before and after supplementation using open circuit spirometry (Parvo-Medics) during graded exercise tests on a treadmill. 4 high-speed runs to exhaustion were conducted at 110, 105, 100, and 90% of peak velocity to determine critical velocity (CV). Distances achieved were plotted over times-to-exhaustion and linear regression was used to determine the slopes (critical velocity, CV) assessing aerobic performance. The results indicated that Cr loading did not positively or negatively influence VO2max, CV, time to exhaustion or body mass (p>0.05). These results suggest Cr supplementation may be used in aerobic running activities without detriments to performance.
Publisher: Wiley
Date: 15-12-2015
DOI: 10.1111/CPF.12328
Abstract: This investigation aimed to compare hydrostatic weighing (HW) with near-infrared interactance (NIR) and skinfold measurements (SKF) in estimating body fat percentage (FAT%) in rowing athletes. FAT% was estimated in 20 elite male rowers (mean ± SD: age = 24·8 ± 2·2 years, height = 191·0 ± 6·8 cm, weight = 86·8 ± 11·3 kg, HW FAT% = 11·50 ± 3·16%) using HW with residual volume, 3-site SKF and NIR on the biceps brachii. Predicted FAT% values for NIR and SKF were validated against the criterion method of HW. Constant error was not significant for NIR (-0·06, P = 0·955) or SKF (-0·20, P = 0·813). Neither NIR (r = 0·045) nor SKF (r = 0·229) demonstrated significant validity coefficients when compared to HW. The standard error of the estimate values for NIR and SKF were both less than 3·5%, while total error was 4·34% and 3·60%, respectively. When compared to HW, SKF and NIR provide similar mean values when compared to HW, but the lack of apparent relationships between in idual values and borderline unacceptable total error may limit their application in this population.
Publisher: Informa UK Limited
Date: 06-2011
DOI: 10.1080/02640414.2011.571274
Abstract: The aims of this study were to examine the use of the critical velocity test as a means of predicting 2000-m rowing ergometer performance in female collegiate rowers, and to study the relationship of selected physiological variables on performance times. Thirty-five female collegiate rowers (mean ± s: age 19.3 ± 1.3 years height 1.70 ± 0.06 m weight 69.5 ± 7.2 kg) volunteered to participate in the study. Rowers were ided into two categories based on rowing experience: varsity (more than 1 year collegiate experience) and novice (less than 1 year collegiate experience). All rowers performed two continuous graded maximal oxygen consumption tests (familiarization and baseline) to establish maximal oxygen uptake (VO(2max)), peak power output, and power output at ventilatory threshold. Rowers then completed a critical velocity test, consisting of four time-trials at various distances (400 m, 600 m, 800 m, and 1000 m) on two separate days, with 15 min rest between trials. Following the critical velocity test, rowers completed a 2000-m time-trial. Absolute VO(2max) was the strongest predictor of 2000-m performance (r = 0.923) in varsity rowers, with significant correlations also observed for peak power output and critical velocity (r = 0.866 and r = 0.856, respectively). In contrast, critical velocity was the strongest predictor of 2000-m performance in novice rowers (r = 0.733), explaining 54% of the variability in performance. These findings suggest the critical velocity test may be more appropriate for evaluating performance in novice rowers.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jeffrey Stout.