ORCID Profile
0000-0003-3788-3700
Current Organisations
Queensland University of Technology
,
Deakin University
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Publisher: South Florida Publishing LLC
Date: 03-04-2021
DOI: 10.34117/BJDV7N4-040
Abstract: Diferentes tipos de programas de treinamento resistido resultam em diferente estresse metabólico e demandas cardiovasculares, o que poderia influenciar adaptações na modulação autonômica cardíaca. O estímulo preciso do treinamento resistido e os mecanismos responsáveis por promover a melhora na variabilidade da frequência cardíaca (VFC) não são claros. Para examinar os efeitos na VFC após dois modelos de periodização de treinamento resistido em adultos idosos. Vinte e dois sujeitos foram ididos em dois grupos: periodização de sessão mista (MSP, n = 11) e periodização tradicional (TP, n = 11). Os sujeitos foram testados antes e após 24 sessões de treinamento resistido para VFC (tempo, frequência e análise não linear), cinco repetições máximas (5-RM) para o leg press e flexora senatada. Apenas o TP melhorou a VFC. O RR médio possivelmente aumentou com prováveis melhorias em RMSSD, SD1 e APEN. Muito provavelmente mudanças positivas foram observadas em HF. As diferenças foram associadas a tamanhos de efeito variando de 0,16 a 0,69. Para todos esses parâmetros autonômicos cardíacos no grupo MSP, a magnitude das mudanças foi classificada como trivial. A abordagem MSP resultou em prováveis ajustes autonômicos inferiores em RR, HF, RMSSD, HF, SD1 e APEN médios. Ambos os grupos provavelmente aumentaram o desempenho de força no leg press e na flexora sentada com possivelmente e provavelmente maiores melhorias observadas no grupo MSP, respectivamente. Aumentos graduais na intensidade prescrita pela abordagem TP podem fornecer melhores ajustes autonômicos do que as intensidades repentinamente mais altas sugeridas pelo MSP. TP parece ser mais eficaz para melhorias da função autonômica, enquanto MSP para força em adultos idosos.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2019
DOI: 10.1519/SSC.0000000000000407
Abstract: BECAUSE OF RECENT DEMOGRAPHIC CHANGES WITH A GREATER PROPORTION OF ELDERLY PEOPLE IN THE WORLD, PHYSICAL INDEPENDENCE AMONG OLDER ADULTS IS BECOMING INCREASINGLY MORE IMPORTANT. THIS MINIREVIEW SUMMARIZES AND DISCUSSES NEUROMUSCULAR ADAPTATIONS IN RESPONSE TO RESISTANCE TRAINING WITH DIFFERENT CONTRACTION VELOCITIES IN UNTRAINED ELDERLY. SLOW AND FAST VELOCITY TRAINING CAN TO A SIMILAR EXTENT IMPROVE MUSCLE MASS AND MAXIMAL FORCE. HOWEVER, FAST VELOCITY RESISTANCE TRAINING IS SUPERIOR FOR IMPROVING POWER OUTPUT, EXPLOSIVE FORCE, AND FUNCTIONAL CAPACITY. THUS, FAST VELOCITY RESISTANCE TRAINING PROVIDES MORE EFFICIENT NEUROMUSCULAR ADAPTATIONS, INCREASING SIMULTANEOUSLY STRENGTH, POWER, EXPLOSIVE FORCE, MUSCLE MASS, AND FUNCTIONAL CAPACITY OF UNTRAINED ELDERLY.
Publisher: Cold Spring Harbor Laboratory
Date: 11-12-2020
DOI: 10.1101/2020.12.11.420570
Abstract: This study tested the hypothesis that estimates of persistent inward currents (PICs) in the human plantar flexors would increase with the level of voluntary drive. Twenty-one participants volunteered for this study (29.2±2.6 years). High-density surface electromyograms were collected from soleus and gastrocnemius medialis during r -shaped isometric contractions to 10%, 20%, and 30% (torque rise of 2%/s and 30-s duration) of each participant’s maximal torque. Motor units identified in all the contraction intensities were included in the paired-motor unit analysis to calculate delta frequency (ΔF) and estimate the PICs. Increases in PICs were observed from 10% to 20% (Δ=0.6 pps p .001) and 20% to 30% (Δ=0.5 pps p .001) in soleus , and from 10% to 20% (Δ=1.2 pps p .001) but not 20% to 30% (Δ=0.09 pps p=0.724) in gastrocnemius medialis . Maximal discharge rate increased for soleus and gastrocnemius medialis from 10% to 20% (respectively, Δ=1.75 pps, p .001 and Δ=2.43 pps, p .001) and 20% to 30% (respectively, Δ=0.80 pps, p .017 and Δ=0.92 pps, p=002). The repeated-measures correlation identified associations between ΔF and increases in maximal discharge rate for both soleus (r=0.64 p .001) and gastrocnemius medialis (r=0.77 p .001). An increase in voluntary drive tends to increase PIC strength, which has key implications for the control of force but also for comparisons between muscles or between studies when relative force levels might be different. These data indicate that increases in voluntary descending drive lify PICs in humans and provide an important spinal mechanism for motor unit firing, and thus force output modulation.
Publisher: Informa UK Limited
Date: 09-07-2020
Publisher: Springer Science and Business Media LLC
Date: 10-09-2020
Publisher: Elsevier BV
Date: 10-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2018
DOI: 10.1519/JSC.0000000000002752
Abstract: Berzerra, ES, Orssatto, LBR, Moura, BM, Willardson, JM, Simão, R, and Moro, ARP. Mixed session periodization as a new approach for strength, power, functional performance, and body composition enhancement in aging adults. J Strength Cond Res 32(10): 2795–2806, 2018—The purpose of this study was to compare the effects of mixed session periodization (MSP) vs. traditional periodization (TP) on strength, power, functional performance, and body composition in aging adults. Forty-five healthy aging adults were randomly ided into 3 groups: MSP, TP, and Control. Subjects were tested before the intervention for baseline values (week 4) and then repeated testing during (week 7 and week 11), as well as after the intervention (week 15). Subjects were tested on the following performance measures: 5 repetition maximum (5RM) leg press and seated leg curl 12RM cable chest press countermovement jump (CMJ) and squat jump up-and-down stairs timed up and go (TUG) and body composition. All comparisons were analyzed through a mixed-model analysis with repeated measures (group × time) and with Bonferroni post hoc tests ( p ≤ 0.05). After the intervention, no significant differences were observed between experimental groups however, the MSP and TP groups demonstrated significantly greater values vs. the Control group in the 5RM leg press ( p 0.01), seated leg curl ( p 0.01), and 12RM cable chest press ( p 0.001). For CMJ performance, the MSP and TP groups significantly increased at week 7 ( p 0.001). The MSP and TP groups significantly improved functional task performance, including TUG ( p 0.001), upstairs ( p 0.01), and downstairs ( p 0.01) after training. Furthermore, body composition for the lower limbs significantly changed for the MSP and TP groups, with increased fat-free mass ( p 0.001) and decreased fat mass ( p 0.01) after training. In conclusion, the MSP and TP models used in this study were equally effective in developing strength, power, and functional performance while increasing fat-free mass and improving body fat percentage in aging adults. However, it should be considered that the MSP protocol did result in greater effect sizes in lower-limb strength, lower-limb fat-free mass, up-and-down stair, and TUG performance.
Publisher: American Physiological Society
Date: 25-10-2023
Publisher: Frontiers Media SA
Date: 26-06-2019
Publisher: Springer Science and Business Media LLC
Date: 30-10-2021
Publisher: Mary Ann Liebert Inc
Date: 12-2020
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.MAD.2018.06.005
Abstract: Ageing leads to substantial force production capacity reductions, which is an indicator of frailty and disability, and a mortality predictor in elders. Understanding the age-dependent neuromuscular mechanisms underlying force reductions can optimize healthcare professionals' exercise protocol choices for patients and allows researchers to investigate new interventions to mitigate these reductions. Our primary goal was to provide an updated review about the main neural and musculotendinous mechanisms underpinning age-related reductions in force capacity. Our secondary goal was to summarize how aerobic and strength training can lessen these age-related reductions. This review suggests that several steps in the force production pathway, from cortical to muscular mechanisms, are negatively affected by ageing. However, combining aerobic and strength training can attenuate these effects. Strength training (i.e. moderate to high- intensity, progressive volume, accentuated eccentric loading and fast concentric contraction velocity) can increase overall force production capacity by producing beneficial neural and musculotendinous adaptations. Additionally, aerobic training (i.e. moderate and high intensities) plays an essential role in preserving the structure and function of the neuromuscular system.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 08-2021
Publisher: Cold Spring Harbor Laboratory
Date: 02-07-2021
DOI: 10.1101/2021.06.25.21259561
Abstract: This study aimed to investigate short-interval intracortical inhibition (SICI) and muscle function in the Triceps surae of runners with mid-portion Achilles tendinopathy (AT). Runners with (n=11) and without (n=13) AT were recruited. Plantar flexor isometric peak torque and rate of torque development (RTD) were measured using an isokinetic dynamometer. Triceps surae endurance was measured as single leg heel raise (SLHR) to failure test. SICI was assessed using paired-pulse transcranial magnetic stimulation during a sustained contraction at 10% of plantar flexor isometric peak torque. Triceps surae SICI was 14.3% (95%CI: -2.1 to 26.4) higher in AT than control group (57.9%, 95%CI: 36.2, to 79.6 and 43.6% 95%CI:16.2 to 71.1 p=0.032) irrespective of the tested muscle. AT performed 16 (95%CI: 7.9 to 23.3, p .001) fewer SLHR repetitions on the symptomatic side compared to controls, and 14 (95%CI: 5.8 to 22.0, p=0.004), fewer SLHR repetitions on the non-symptomatic compared to controls. We found no between-groups differences in isometric peak torque (p=0.971) or RTD (p=0.815). Our data suggest greater intracortical inhibition for the Triceps surae muscles for the AT group accompanied by reduced SLHR endurance, without deficits in isometric peak torque or RTD. The increased SICI observed in the AT group could be negatively influencing Triceps surae endurance thus, rehabilitation aiming to reduce intracortical inhibition should be considered to improve patient outcomes. Furthermore, SLHR is a useful clinical tool to assess plantar flexor function in AT patients.
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.MAD.2022.111647
Abstract: Nervous system maladaptation is linked to the loss of maximal strength and motor control with aging. Motor unit discharge rates are a critical determinant of force production thus, lower discharge rates could be a mechanism underpinning maximal strength and motor control losses during aging. This meta-analysis summarized the findings of studies comparing motor unit discharge rates between young and older adults, and examined the effects of the selected muscle and contraction intensity on the magnitude of discharge rate difference between these two groups. Estimates from 29 studies, across a range of muscles and contraction intensities, were combined in a multilevel meta-analysis, to investigate whether discharge rates differed between young and older adults. Motor unit discharge rates were higher in younger than older adults, with a pooled standardized mean difference (SMD) of 0.66 (95%CI= 0.29-1.04). Contraction intensity had a significant effect on the pooled SMD, with a 1% increase in intensity associated with a 0.009 (95%CI= 0.003-0.015) change in the pooled SMD. These findings suggest that reductions in motor unit discharge rates, especially at higher contraction intensities, may be an important mechanism underpinning age-related losses in maximal force production.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.JBMT.2017.09.020
Abstract: The aims of this pilot study were to verify which muscle strength tests better explain bone mineral content (BMC) of the femoral neck and lumbar spine and to develop predictive equations to estimate femoral neck and lumbar spine BMC. Twenty-nine subjects aged 56-76 years old (12 women and 17 men) participated in the study. Femoral neck and lumbar spine BMC was evaluated by Dual X-ray absorptiometry (DXA). Muscle strength measurements included maximal isometric voluntary contractions of knee extensors and flexors, vertical jump, 5-repetition maximum of the leg press (5-RM
Publisher: Wiley
Date: 25-08-2020
DOI: 10.1111/SMS.13788
Publisher: Cold Spring Harbor Laboratory
Date: 15-08-2023
DOI: 10.1101/2023.08.14.553177
Abstract: Runners with Achilles tendinopathy (AT) have lower neural drive to gastrocnemius lateralis (GL) and it has been shown that modified foot position during plantarflexion activity affects motor unit discharge properties of GL . This paper tested the motor unit (MU) responses of GL and gastrocnemius medialis (GM) to feet-neutral and feet-in . We recruited runners with (n=18) and without (n=19) AT for experiment 1(EXP1) and nine healthy in iduals for experiment 2(EXP2). High-Density electromyography was used to analyse MU discharge rates (MUDR) for GL and GM , during an isometric plantarflexion (EXP1) with feet-neutral and feet-in and during a 30%-peak torque (EXP2) using a dynamometer. In EXP1 MUDR were lower during feet-in in GL (p .001) and in GM (p .001), without group difference (p=0.84). Furthermore, cumulative spike train analysis showed no difference in GL or GM neural drive between group or condition. EXP2 showed no condition differences in GL (p=0.91) and lower MUDR in GM (p=0.01). Finally, the AT group have lower triceps surae endurance observed during single leg heel raise. Our data indicate that feet-in reduces gastrocnemii MUDR, compared to feet-neutral , irrespective of tendinopathy. Current understanding of modulation strategies to GL driven by feet position is conflicting thus, plantarflexion using feet in may not be a viable treatment strategy for AT. Plantarflexion performed with feet inwards does not increase the neural drive to gastrocnemius lateralis as suggested in the literature. In fact, the feet-in condition reduced the motor unit discharge rates in both gastrocnemii during isometric plantarflexion and isometric plantarflexion using dynamometry. Therefore, this is not a viable treatment strategy for runners with Achilles tendinopathy. Furthermore, prioritising strategies to improve triceps surae endurance should be a key component in physiotherapy program.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.JBMT.2017.09.023
Abstract: The aim of this study was to investigate whether 12 weeks of leg press strength training exercise could affect the conventional and functional hamstring:quadriceps ratios in the elderly. Twelve elderly participants were submitted to a 12 week progressive training protocol (two sessions/week) using a 45° leg press exercise. A significant increase in the one repetition maximum was observed after 4, 8, and 12 weeks (p = 0.001, p < 0.001, and p 0.314) after 12 weeks of training. The functional ratio (eccentric knee flexor peak torque:concentric knee extensor peak torque) reduced significantly after 8 (p = 0.034) and 12 (p = 0.036) weeks of strength training. Although the 45° leg press exercise requires knee extensor and flexor, hip extensor, and plantar flexor muscle strength, our findings suggest that the isolated use of the 45° leg press exercise reduces the knee functional ratio after 8 weeks of training. Therefore, 45° leg press exercise alone, without a hamstring exercise, should not be recommended for elderly in iduals.
Publisher: Wiley
Date: 24-07-2023
DOI: 10.1113/JP284603
Abstract: Nervous system deterioration is a primary driver of age‐related motor impairment. The motor neurones, which act as the interface between the central nervous system and the muscles, play a crucial role in lifying excitatory synaptic input to produce the desired motor neuronal firing output. For this, they utilise their ability to generate persistent (long‐lasting) depolarising currents that increase cell excitability, and both lify and prolong the output activity of motor neurones for a given synaptic input. Modulation of these persistent inward currents (PICs) contributes to the motor neurones’ capacities to attain the required firing frequencies and rapidly modulate them to competently complete most tasks. Thus, PICs are crucial for adequate movement generation. Impairments in intrinsic motor neurone properties can impact motor unit firing capacity, with convincing evidence indicating that the PIC contribution to motor neurone firing is reduced in older adults. Indeed, this could be an important mechanism underpinning the age‐related reductions in strength and physical function. Furthermore, resistance training has emerged as a promising intervention to counteract age‐associated PIC impairments, with changes in PICs being correlated with improvements in muscular strength and physical function after training. In this review, we present the current knowledge of the PIC magnitude decline during ageing and discuss whether reduced serotonergic and noradrenergic input onto the motor neurones, voltage‐gated calcium channel dysfunction or inhibitory input impairments are candidates that: (i) explain age‐related reductions in the PIC contribution to motor neurone firing and (ii) underpin the enhanced PIC contribution to motor neurone firing following resistance training in older adults. image
Publisher: Elsevier BV
Date: 05-2020
DOI: 10.1016/J.JSAMS.2019.12.004
Abstract: Investigate the acute effects of repeated combat sports matches on vertical jump and handgrip strength performance in grappling and striking modalities. Systematic review. PubMed, Scopus, and Web of Science databases were searched. The following eligibility criteria for selecting studies were adopted: Population: Combat sports athletes Intervention: Official or simulated matches Comparator: Baseline versus after-matches performance Outcome: Vertical jump and/or handgrip strength performance. CRD42019129264 RESULTS: The systematic search resulted in 13 studies, including Brazilian jiu-jitsu, Greco-Roman, judo, taekwondo, and wrestling (freestyle and Greco-Roman) modalities, and a erse number of repeated matches (i.e. 1-5). None of the studies adopted a randomized and controlled design and, consequently, none of them was classified as high quality. Brazilian jiu-jitsu and freestyle wrestling athletes presented an earlier onset of fatigue in upper and lower limbs, while judo and Greco Roman wrestling presented a later onset, from the third match. In taekwondo athletes, no fatigue was observed in the lower limbs, while handgrip strength decreased. However, studies have reported unclear data regarding the time-course of lower and upper limbs' fatigue following repeated matches in taekwondo. Both upper and lower limbs performance were affected after repeated matches in grappling combat sports when assessed by handgrip strength and vertical jump performance. In taekwondo, the studies have shown unclear results concerning the effects of repeated matches on upper and lower limb performance. There is a lack of studies classified as high-quality and investigations into the neuromuscular mechanisms underpinning fatigue after the repeated matches.
Publisher: Korean Society of Exercise Rehabilitation
Date: 24-08-2018
Publisher: Cold Spring Harbor Laboratory
Date: 11-08-2022
DOI: 10.1101/2022.08.08.503135
Abstract: A well-coordinated control of motor neuronal persistent inward currents (PICs) via diffuse neuromodulation and local inhibition is essential to ensure motor units discharge at required times and frequencies. Current best estimates indicate that PICs are reduced in older adults however, it is not yet known whether PIC facilitation-inhibition control is also altered with ageing. We investigated the responses of PICs to i) a remote handgrip contraction, which is believed to diffusely increase serotonergic input onto motor neurones, and ii) tendon vibration of the antagonist muscle, which elicits reciprocal inhibition, in both young and older adults. High-density surface electromyograms were collected from soleus and tibialis anterior of 18 young and 26 older adults during triangular-shaped plantar and dorsiflexion contractions to 20% (handgrip experiments) and 30% (vibration experiments) of maximum torque (rise-decline rate of 2%/s). The paired-motor-unit analysis was used to calculate ΔF, which is assumed proportional to PIC strength. ΔF increased in both soleus (0.55pps, 16.0%) and tibialis anterior (0.42pps, 11.4%) during the handgrip contraction independent of age. However, although antagonist tendon vibration reduced ΔF in soleus (0.28pps, 12.6%) independent of age, less reduction was observed in older (0.42pps, 10.7%) than young adults (0.72pps, 17.8%) in tibialis anterior . Our data indicate a preserved ability of older adults to lify PICs following a remote handgrip contraction, during which increased serotonergic input onto the motor neurones is expected, in both lower leg muscles. However, PIC deactivation in response to reciprocal inhibition was impaired with ageing in tibialis anterior despite being preserved in soleus . Motor neuronal persistent inward currents (PICs) are lified via diffuse neuromodulation and deactivated by local inhibition to ensure motor units discharge at required times and frequencies, allowing a normal motor behaviour. PIC litudes appear to be reduced with ageing, however it is not known whether PIC facilitation-inhibition control is also altered. Remote handgrip contraction, which should diffusely increase serotonergic input onto motor neurones, lified PICs similarly in both soleus and tibialis anterior of young and older adults. Antagonist tendon vibration, which induces reciprocal inhibition, reduced PICs in soleus in both young and older adults but had less effect in tibialis anterior in older adults. Our data suggest that older adults have preserved soleus PIC facilitation during lowintensity contractions, equivalent to activities such as standing and walking. However, a reduced reciprocal inhibition of PICs in tibialis anterior may contribute to locomotion impairments, such as increases in soleus-tibialis anterior co-activation during propulsion.
Publisher: The Company of Biologists
Date: 2020
DOI: 10.1242/JEB.229922
Abstract: Prolonged (≥60 s) passive muscle stretching acutely reduces maximal force production at least partly through a suppression of efferent neural drive. The origin of this neural suppression has not been determined, however some evidence suggests that reductions in the litude of persistent inward currents (PICs) in the motoneurons may be important. The aim of the present study was to determine whether acute passive (static) muscle stretching affects PIC strength in gastrocnemius medialis (GM) and soleus (SOL) motor units. We calculated the difference in instantaneous discharge rates at recruitment and derecruitment (ΔF) for pairs of motor units in GM and SOL during triangular isometric plantar flexor contractions (20% maximum) both before and immediately after a 5-min control period and immediately after five 1-min passive plantar flexor stretches. After stretching there was a significant reduction in SOL ΔF (−25.6% 95%CI=−45.1 to −9.1 %, p=0.002) but not GM ΔF. These data suggest passive muscle stretching can reduce the intrinsic excitability, via PICs, of SOL motor units. These findings (1) suggest that PIC strength might be reduced after passive stretching, (2) are consistent with previously-established post-stretch decreases in SOL but not GM EMG litudes during contraction, and (3) indicate that reductions in PIC strength could underpin the stretch-induced force loss.
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.EXGER.2019.110731
Abstract: Reduced levels of functional capacity in older adults are related to lower quality of life, frailty, and sarcopenia, and can increase risk of falling, fractures and hospitalisation. Resistance training is an effective method to attenuate age-related functional declines. Based on the findings that muscle power and explosive strength are strongly associated with functional performance in older adults, it has been suggested that fast-intended-velocity resistance training may elicit greater improvements in functional capacity when compared to moderate-velocity resistance training. However, currently, there is no high-quality systematic review and meta-analysis supporting this assertion. The present study compared the magnitude of functional capacity improvements following resistance training performed with fast-intentional velocity versus moderate velocity. Pubmed, Scopus, and Web of Science databases were searched from inception to January 2019. The following eligibility criteria for selecting studies was adopted: Participants aged ≥60 years resistance training based intervention for lower limbs performed solely with slow to moderate concentric velocity (≥2 s for each concentric phase) or solely with the intention of maximising velocity (i.e., as fast as possible) and at least one functional test for lower limbs, with pre- and post-intervention measurements. When studies employed multiple functional tests, a single (pooled) standardised mean difference was calculated and presented as combined functional capacity. In addition, functional tests were grouped accordingly to their specificity for the sub-groups meta-analyses. Fifteen studies were selected (high quality, n = 3 and pre-registered, n = 2). The results presented heterogeneity and small-studies publication bias, leading to a biased advantage for fast-intended-velocity resistance training (95%CI = 0.18, 0.65 I
Publisher: Wiley
Date: 28-09-2023
DOI: 10.1113/JP285181
Publisher: Springer Science and Business Media LLC
Date: 10-01-2023
DOI: 10.1186/S40798-022-00550-8
Abstract: Plyometric training can be performed through many types of exercises involving the stretch-shortening cycle in lower limbs. In the last decades, a high number of studies have investigated the effects of plyometric training on several outcomes in different populations. To systematically review, summarize the findings, and access the quality of published meta-analyses investigating the effects of plyometric training on physical performance. Systematic umbrella review of meta-analyses. Meta-analyses were identified using a systematic literature search in the databases PubMed/MEDLINE, Scopus, SPORTDiscus, Web of Science, Cochrane Library and Scielo. Meta-analyses that examined the effects of plyometric training on physical fitness in different populations, age groups, and sex. Twenty-nine meta-analyses with moderate-to-high methodological quality were included in this umbrella review. We identified a relevant weakness in the current literature, in which five meta-analyses included control group comparisons, while 24 included pre-to-post-effect sizes. Trivial-to-large effects were found considering the effects of plyometric training on physical performance for healthy in iduals, medium-trivial effects for the sports athletes’ groups and medium effects for different sports athletes’ groups, age groups, and physical performance. The available evidence indicates that plyometric training improves most related physical fitness parameters and sports performance. However, it is important to outline that most meta-analyses included papers lacking a control condition. As such, the results should be interpreted with caution. PROSPERO number : CRD42020217918.
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.NUT.2021.111344
Abstract: High-intensity intermittent exercise (HIIE) may enhance the antiinflammatory status. The juçara fruit juice (JFJ) has well-established antioxidant and antiinflammatory properties. This study investigated the effect of JFJ consumption on the inflammatory response to HIIE in physically active subjects. In a randomized crossover design, 15 men were assigned to drink 250 mL of either JFJ or water (control) 1 h before a cycling HIIE session (seven sets of 60 s at 100% peak power output 75 s recovery between sets). Blood s les were obtained before and at 0, 30, and 60 min post-HIIE, and the serum was analyzed for interleukin (IL)-6, IL-1β, IL-8, IL-10, tumor necrosis factor-α, and cortisol. After HIIE, the IL-6 levels were higher than baseline (percent change) at 30 min (P = 0.041) and 60 min (P = 0.038) for the control, but were unaffected by JFJ. IL-10 was higher in the JFJ group than in the control at 30 min (d = ‒0.63). Tumor necrosis factor-α was lower than baseline at 30 min for the control (d = ‒0.71) and at 60 min for the JFJ group (d = ‒0.60). For control, cortisol increased to higher than the baseline at 30 and 60 min (d = 0.54 and d = 0.76, respectively). For the JFJ group, the cortisol levels were significantly higher than the baseline at 30 min (P = 0.022). Performance during sprints was higher in the JFJ group than in the control (P = 0.002). In the control group, performance was with both IL-6 (semipartial correlation sr = -0.59, large effect size) and cortisol at 0 h (sr = -0.52, large effect size). JFJ intake attenuated the antiinflammatory response to HIIE, possibly resulting from a lower degree of muscle stress.
Publisher: FapUNIFESP (SciELO)
Date: 2021
DOI: 10.1590/1980-0037.2021V23E82849
Abstract: Abstract Manipulation of resistance training variables has been shown to have a substantial effect on muscular adaptations. A major variable in this process is exercise selection. In addition to the effectiveness of a given exercise to recruit the target muscle groups, safety considerations and in idual comfort during execution of a lift should be considered. The correct biomechanics of the chosen exercise will assist in promoting desired muscle adaptations, while proper safety procedures will reduce risk of injury. Lifting comfort will facilitate enjoyment and foster adherence to the program. Therefore, the purpose of this paper was to offer guidelines for selection of resistance training exercises based on the Efficiency, Safety, and Comfort Analysis Method (ESCAM).
Publisher: Springer Science and Business Media LLC
Date: 09-03-2020
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 21-11-2022
DOI: 10.1519/SSC.0000000000000749
Abstract: This narrative review aims to describe and provide usage directions for different types of judo-specific assessments based on the physical demands required by athletes during training and competition. Several judo-specific tests have been developed to test different physical capacities (e.g., aerobic and anaerobic capacities, strength endurance, etc). Judo skills or techniques are used to identify variables involved in performance, such as uchi-komi (technique repetition or repetition training), throws, displacements, grips on the judogi , and the like. Although all the tests can be used to identify the physical profile of each athlete and monitor training effects (acute, subacute, or chronic), some can also be used to prescribe training loads. The judo-specific tests analyzed in this study are a valid and accessible alternative to assess the physical performance of judo athletes, regardless of sex or weight category. These tests are recommended at different times (over the season) to monitor training effects or to prescribe training loads (when possible). Future studies could investigate other methods of validity (e.g., construct validity) in differentiated groups, as well as the sensitivity of the tests to detect changes (even if small) in performance.
Publisher: Springer Science and Business Media LLC
Date: 19-11-2019
Publisher: Springer Science and Business Media LLC
Date: 23-08-2017
DOI: 10.1007/S40520-017-0820-X
Abstract: Accuracy is essential to the validity of functional capacity measurements. To evaluate the error of measurement of functional capacity tests for elders and suggest the use of the technical error of measurement and credibility coefficient. Twenty elders (65.8 ± 4.5 years) completed six functional capacity tests that were simultaneously filmed and timed by four evaluators by means of a chronometer. A fifth evaluator timed the tests by analyzing the videos (reference data). The means of most evaluators for most tests were different from the reference (p < 0.05), except for two evaluators for two different tests. There were different technical error of measurement between tests and evaluators. The Bland-Altman test showed difference in the concordance of the results between methods. Short duration tests showed higher technical error of measurement than longer tests. In summary, tests timed by a chronometer underestimate the real results of the functional capacity. Difference between evaluators' reaction time and perception to determine the start and the end of the tests would justify the errors of measurement. Calculation of the technical error of measurement or the use of the camera can increase data validity.
Publisher: Cold Spring Harbor Laboratory
Date: 23-06-2021
DOI: 10.1101/2021.06.23.449552
Abstract: Age-related deterioration within both motor neurones and monoaminergic systems should theoretically reduce neuromodulation by weakening motor neuronal persistent inward current (PIC) litude. However, this assumption remains untested. Surface electromyographic signals were collected using two 32-channel electrode matrices placed on soleus and tibialis anterior of 25 older adults (70±4years) and 17 young adults (29±5 years) to investigate motor unit discharge behaviours. Participants performed triangular-shaped plantar and dorsiflexion contractions to 20% of maximum torque at a rise-decline rate of 2%/s of each participant’s maximal torque. Pairwise and composite paired-motor unit analyses were adopted to calculate delta frequency (ΔF), which has been used to differentiate between the effects of synaptic excitation and intrinsic motor neuronal properties and is assumed to be proportional to PIC litude. Soleus and tibialis anterior motor units in older adults had lower ΔFs calculated with either the pairwise [−0.99 and −1.46 pps −35.4 and − 33.5%, respectively] or composite (−1.18 and −2.28 pps −32.1 and −45.2%, respectively) methods. Their motor units also had lower peak discharge rates (−2.14 and −2.03 pps −19.7 and −13.9%, respectively) and recruitment thresholds (−1.50 and −2.06% of maximum, respectively) than young adults. These results demonstrate reduced intrinsic motor neurone excitability during low-force contractions in older adults, likely mediated by decreases in the litude of persistent inward currents. Our findings might be explained by deterioration in the motor neurones or monoaminergic systems and could contribute to the decline in motor function during ageing these assumptions should be explicitly tested in future investigations.
Publisher: Canadian Science Publishing
Date: 06-2018
Abstract: The aim of the present study was to compare muscular performance and body composition changes following low-volume resistance-training programs consisting of multi-joint (MJ) exercises (cable chest press and seated row) versus a combination of multi- and single-joint (MJ+SJ) exercises (cable chest press, seated row, biceps curl, and triceps extension). Thirty untrained healthy aging adults were randomly assigned to 3 groups: MJ (n = 11), MJ+SJ (n = 11), and control (n = 8). Twelve-repetition maximums (12-RMs) for the cable chest press and seated row, localized muscular endurance for the elbow flexors handgrip strength, and body composition were assessed before and after the 8-week training program. All comparisons were analyzed via a mixed-model analysis with repeated measures (group × time) and the Bonferroni post hoc test (p 0.05). The MJ and MJ+SJ groups increased performance in the 12-RM cable chest press (MJ = 61.5% ± 24.6% and MJ+SJ = 71.1% ± 25.6%), 12-RM seated row (MJ = 46.4% ± 26.3% and MJ+SJ = 51.5% ± 21.0%), localized muscular endurance (MJ = 24.7% ± 16.7% and MJ+SJ = 37.0% ± 11.4%), and handgrip strength (MJ = 9.3% ± 10.4% and MJ+SJ = 16.6% ± 25.3%) after the intervention. Body composition (i.e., trunk and upper limb fat and lean mass) did not change for any groups. No significant differences were observed between the MJ versus the MJ+SJ protocols after the intervention for any variables. In conclusion, for aging adults, either MJ or MJ+SJ low-volume resistance training resulted in similar increases in 12-RM, localized muscular endurance, and handgrip strength, without changes in body composition after 8 weeks of training.
Publisher: Cold Spring Harbor Laboratory
Date: 16-12-2020
DOI: 10.1101/2020.12.15.422812
Abstract: Nervous system maladaptation is linked to the loss of maximal strength production and motor control with aging. Motor unit discharge rates are a critical determinant of force production thus, lower discharge rates could be a mechanism underpinning maximal strength and motor control losses during aging. This meta-analysis summarized the findings of studies comparing motor unit discharge rates between young and older adults, and examined the effect of distinct muscles and contraction intensities on the magnitude of discharge rates difference between these two groups. Eligible studies were combined in a meta-analysis, including tested contraction intensities and muscles in different levels, to investigate whether there were differences in discharge rates between younger and older adults. Motor unit discharge rates were higher in younger adults compared to older adults, with a pooled standardized mean difference (SMD) for all studies of 0.63 (95%CI= 0.27 to 0.99). Contraction intensity had a significant effect on the pooled SMD, with a 1% increase in intensity associated with a 0.009 (95%CI= 0.003 to 0.015) change in the pooled SMD. These findings suggest that the reductions in motor unit discharge rates, especially at higher contraction intensities, may be an important mechanism underpinning age-related losses in maximal strength production.
Publisher: Springer Science and Business Media LLC
Date: 11-2007
DOI: 10.1038/NATURE06341
Publisher: Wiley
Date: 27-01-2023
DOI: 10.1111/SMS.14312
Abstract: Examine the effects of 42°C hot‐water immersion on muscle contraction function and motor unit discharge rates. Voluntary and evoked contraction assessments were examined first with a concomitant increase in the core and muscle temperature, and thereafter with increased muscle temperature but cooled core temperature. Fifteen participants (24.9 ± 5.6 years) performed neuromuscular assessments before, after, and ~15‐min after either 90‐min of 42°C (hot) or 36°C (control) water immersion. Maximal voluntary contraction (MVC) assessment of knee extension was performed along with surface electromyography (sEMG) ( vastus lateralis and medialis [VL, VM]) and voluntary activation level (VAL). Resting evoked twitch was elicited for peak torque and time to peak torque analysis. In addition, the VL and VM motor unit discharge rates (MUDR) were measured. After hot‐water immersion (core temperature ↑1°C muscle temperature ↑2.4°C), MVC torque and VAL decreased ( p 0.05). The sEMG (VL and VM) and peak twitch torque did not change ( p 0.05), while time to peak torque decreased ( p = 0.007). The VL and VM MUDR decreased, showing a time effect, after both water immersion conditions (36 and 42°C) ( p 0.001). Fifteen minutes after the hot‐water immersion (core temperature at baseline muscle temperature ↑1.4°C), MVC torque returned to baseline, but VAL remained lower. The sEMG (VL and VM) remained unchanged. Peak twitch torque increased ( p 0.002) and time to peak torque remained lower ( p = 0.028). The MUDR remained lower after both water immersion conditions ( p 0.05). Increased core temperature evoked by 42°C hot‐water immersion decreases MVC torque and VAL. However, a passive increase in muscle temperature improved evoked muscle contractile function (i.e., time to peak torque [after] and peak twitch torque [~15 min after]). Moreover, a passive increase in muscle temperature reduced the required MUDR to attain the same torque.
Publisher: Springer Science and Business Media LLC
Date: 06-12-2017
DOI: 10.1007/S40520-017-0873-X
Abstract: While it is accepted that resistance training can improve functional capacity in older in iduals, the neuromuscular source of this improvement has yet to be identified. This study investigated the link between improved neuromuscular performance and functional capacity after a 12-week resistance training period in untrained healthy older in iduals. Fifteen older men and women (60-71 years) adhered to a 4-week control period, followed by 12 weeks of non-linear resistance training for the lower limbs. Maximum dynamic leg press strength (1-RM), maximum isometric knee extension torque and rate of torque development (RTD) were evaluated at - 4, 0, 4, 8, and 12 weeks, and muscle activity was assessed at 0, 4, 8, and 12 weeks. Functional capacity tests (chair rise, stair ascent and descent, and timed up and go) were performed at - 4, 0, and 12 weeks. No changes occurred during the control period, but the group increased their 1-RM strength (from 142 ± 53 to 198 ± 43 kg, p = 0.001), which was accompanied by an increase in vastus lateralis activation (p = 0.008) during the intervention. Increase was observed at all RTD time intervals at week 8 (p < 0.05). Significant improvements in all the functional capacity tests were observed at week 12 (p < 0.05). Despite the expected increase in strength, RTD, muscle activity, and functional capacity, there was no significant relationship between the changes in neuromuscular performance and functional capacity. While resistance training elicits various positive improvements in healthy older in iduals, actual strength gain did not influence the gain in functional capacity. The present study highlights the exact cause that improved the functional capabilities during resistance training are currently unknown.
Publisher: Springer Science and Business Media LLC
Date: 23-11-2022
Publisher: Wiley
Date: 18-12-2022
DOI: 10.1111/SMS.14111
Abstract: This study aimed to investigate short‐interval intracortical inhibition (SICI) and muscle function in the triceps surae of runners with mid‐portion Achilles tendinopathy (AT). Runners with ( n = 11) and without ( n = 13) AT were recruited. Plantar flexor isometric peak torque and rate of torque development (RTD) were measured using an isokinetic dynamometer. Triceps surae endurance was measured as single‐leg heel raise (SLHR) to failure test. SICI was assessed using paired‐pulse transcranial magnetic stimulation during a sustained contraction at 10% of plantar flexor isometric peak torque. Triceps surae SICI was 14.3% (95% CI: −2.1 to 26.4) higher in AT than in the control group (57.9%, 95% CI: 36.2 to 79.6 and 43.6% 95% CI: 16.2 to 71.1, p = 0.032) irrespective of the tested muscle. AT performed 16 (95% CI: 7.9 to 23.3, p 0.001) fewer SLHR repetitions on the symptomatic side compared with controls, and 14 (95% CI: 5.8 to 22.0, p = 0.004), fewer SLHR repetitions on the non‐symptomatic compared with controls. We found no between‐groups differences in isometric peak torque ( p = 0.971) or RTD ( p = 0.815). Our data suggest greater intracortical inhibition for the triceps surae muscles for the AT group accompanied by reduced SLHR endurance, without deficits in isometric peak torque or RTD. The increased SICI observed in the AT group could be negatively influencing triceps surae endurance thus, rehabilitation aiming to reduce intracortical inhibition should be considered to improve patient outcomes. Furthermore, SLHR is a useful clinical tool to assess plantar flexor function in AT patients.
Publisher: Cold Spring Harbor Laboratory
Date: 07-05-2022
DOI: 10.1101/2022.05.05.22274750
Abstract: Deficits in muscle performance could be a consequence of a reduced ability of a motor neuron to increase the rate in which it discharges. This study aimed to investigate motor unit (MU) discharge properties of each Triceps surae muscle (TS), and TS torque steadiness during submaximal intensities in runners with Achilles tendinopathy (AT). We recruited runners with (n=12) and without (n=13) mid-portion AT. MU discharge rate was analysed for each of the TS muscles, using High-Density surface electromyography during 10 and 20% isometric plantar flexor contractions. MU mean discharge rate was lower in the Gastrocnemius lateralis (GL) in AT compared to controls. In AT, GL MU mean discharge rate did not increase as torque increased from 10% peak torque, 8.24pps (95%CI: 7.08 to 9.41) to 20%, 8.52pps (7.41 to 9.63, p=0.540) however, in controls, MU discharge rate increased as torque increased from 10%, 8.39pps (7.25 to 9.53) to 20%, 10.07pps (8.89 to 11.25, p .001). There were no between-group difference in Gastrocnemius medialis (GM) or Soleus (SOL) MU discharge rates. We found no between-groups differences in coefficient of variation of MU discharge rate in any of the TS muscles nor in TS torque steadiness. Our data demonstrates that runners with AT may have a reduced neural drive to GL, failing to increase MU discharge rate to adjust for the increase in torque demand. Further research is needed to understand how interventions focusing on increasing neural drive to GL would affect muscle function in runners with AT.
Publisher: Elsevier BV
Date: 04-2019
Publisher: American Physiological Society
Date: 03-2023
Abstract: Resistance training elicited important alterations in soleus intrinsic motor neuronal excitability, likely mediated by enhanced persistent inward current (PIC) litude, in older adults. Estimates of PICs increased after the training period, accompanied by an enhanced ability to increase PIC litudes at higher contraction intensities. Our data also suggest that changes in PIC contribution to self-sustained discharging may contribute to increases in motor neuron discharge rates, maximal strength, and functional capacity in older adults after resistance training.
Publisher: Wiley
Date: 03-11-2022
DOI: 10.1113/JP283708
Abstract: A well‐coordinated facilitation–inhibition control of motor neuronal persistent inward currents (PICs) via diffuse neuromodulation and local inhibition is essential to ensure motor units discharge at required times and frequencies. Present best estimates indicate that PICs are reduced in older adults however, it is not yet known whether PIC facilitation–inhibition control is also altered with ageing. We investigated the responses of PICs to (i) a remote handgrip contraction, which is believed to diffusely increase serotonergic input onto motor neurones, and (ii) tendon vibration of the antagonist muscle, which elicits reciprocal inhibition, in young and older adults. High‐density surface electromyograms were collected from soleus and tibialis anterior of 18 young and 26 older adults during triangular‐shaped plantar and dorsiflexion contractions to 20% (handgrip experiments) and 30% (vibration experiments) of maximum torque (rise‐decline rate of 2%/s). A paired‐motor‐unit analysis was used to calculate ∆ F , which is assumed to be proportional to PIC strength. Δ F increased in both soleus (0.55 peaks per second (pps), 16.0%) and tibialis anterior (0.42 pps, 11.4%) after the handgrip contraction independent of age. Although antagonist tendon vibration reduced Δ F in soleus (0.28 pps, 12.6%) independent of age, less reduction was observed in older (0.42 pps, 10.7%) than young adults (0.72 pps, 17.8%) in tibialis anterior. Our data indicate a preserved ability of older adults to lify PICs following a remote handgrip contraction, during which increased serotonergic input onto the motor neurones is expected, in both lower leg muscles. However, PIC deactivation in response to reciprocal inhibition was impaired with ageing in tibialis anterior despite being preserved in soleus. image Motor neuronal persistent inward currents (PICs) are facilitated via diffuse neuromodulation and deactivated by local inhibition to ensure motor units discharge at required times and frequencies, allowing normal motor behaviour. PIC litudes appear to be reduced with ageing however, it is not known whether PIC facilitation–inhibition control is also altered. Remote handgrip contraction, which should diffusely increase serotonergic input onto motor neurones, facilitated PICs similarly in both soleus and tibialis anterior of young and older adults. Antagonist tendon vibration, which induces reciprocal inhibition, reduced PICs in soleus in both young and older adults but had less effect in tibialis anterior in older adults. Data from lower‐threshold motor units during low‐force contractions suggest that PIC facilitation is preserved with ageing in soleus and tibialis anterior. However, the effect of reciprocal inhibition on the contribution of PICs to motor neurone discharge seems reduced in tibialis anterior but preserved in soleus.
Publisher: Elsevier BV
Date: 2022
Publisher: Cold Spring Harbor Laboratory
Date: 02-08-2020
DOI: 10.1101/2020.07.31.230029
Abstract: Prolonged (≥60 s) passive muscle stretching acutely reduces maximal force production at least partly through a suppression of efferent neural drive. The origin of this neural suppression has not been determined, however some evidence suggests that reductions in the litude of persistent inward currents (PICs) in the motoneurons may be important. The aim of the present study was to determine whether acute passive (static) muscle stretching affects PIC strength in gastrocnemius medialis (GM) and soleus (SOL) motor units. We calculated the difference in instantaneous discharge rates at recruitment and derecruitment (ΔF) for pairs of motor units in GM and SOL during triangular isometric plantar flexor contractions (20% maximum) both before and immediately after a 5-min control period and immediately after five 1-min passive plantar flexor stretches. After stretching there was a significant reduction in SOL ΔF (−25.6% 95%CI = -45.1 to -9.1 %, p=0.002) but not GM ΔF. These data suggest passive muscle stretching can reduce the intrinsic excitability, via PICs, of SOL motor units. These findings (1) suggest that PIC strength might be reduced after passive stretching, (2) are consistent with previously-established post-stretch decreases in SOL but not GM EMG litudes during contraction, and (3) indicate that reductions in PIC strength could underpin the stretch-induced force loss. Motoneurons require an lification mechanism to operate within the firing frequencies observed during normal motor behaviour. Here we present evidence that this lification mechanism is reduced after passive muscle stretching.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Canadian Science Publishing
Date: 09-2020
Abstract: Power training has been suggested to be effective in improving strength, power, and functional capacity in older adults. However, there is still a lack of systematic investigations reporting its effectiveness for muscle hypertrophy. Thus, this study investigated the effect of power training on muscle hypertrophy and compared its magnitude with traditional moderate-velocity resistance training in older adults. A systematic search was conducted to identify clinical trials investigating the effect of power training on muscle hypertrophy (power training vs. control) and/or comparing the effect of power training versus moderate-velocity resistance training for a meta-analytical approach. Ten studies comparing power training to control conditions and 9 studies comparing power training to moderate-velocity resistance training were selected. Three studies were classified as high quality and 2 were preregistered. The meta-analysis showed that power training was superior for muscle hypertrophy compared with control condition (n = 8 studies standardised mean difference (SMD) = 0.31 95% confidence interval (CI) = 0.04, 0.58 p = 0.029), and resulted in similar hypertrophy compared with moderate-velocity resistance training (n = 7 studies SMD = 0.07 95% CI = –0.18, 0.32 p = 0.50). No significant heterogeneity was observed (p = 0.46 and 0.54, and I 2 = 0% and 0%, respectively). Our data suggest that power training is effective for muscle hypertrophy in older adults, with similar effectiveness as moderate-velocity resistance training. (PROSPERO registration no.: CRD42019128951.) Novelty It is known that power training might be superior to moderate-velocity resistance training for function improvements in older adults, but there was no meta-analysis investigating its effect on muscle hypertrophy. Power training is effective to induce muscle hypertrophy in older adults to a similar extent as moderate-velocity resistance training.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Wiley
Date: 16-11-2021
DOI: 10.1113/JP282370
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.EXGER.2018.03.011
Abstract: Understanding the influence of strength training intensity on subsequent recovery in elderly is important to avoid reductions in physical function during the days following training. Twenty-two elderly were randomized in two groups: G70 (65.9 ± 4.8 years, n = 11) and G95 (66.9 ± 5.1, n = 11). Baseline tests included maximum voluntary isometric contraction (peak torque and rate of torque development - RTD), countermovement jump, and functional capacity (timed up and go, stairs ascent and descent). Then, both groups performed a single strength training session with intensities of 70% (G70) or 95% (G95) of five repetition maximum. The same tests were repeated immediately, 24 h, 48 h, and 72 h after the session. Peak torque was lower than baseline immediately after for both groups and at 24 h for G95. Compared with G70, G95 had lower peak torque at 24 h and 48 h. Countermovement jump, timed up and go, stairs ascent, and RTD at 0-50 ms only differed from baseline immediately after for both groups. RTD at 0-200 ms was lower than baseline immediately after and 24 h after the session for both groups. In conclusion, reduced physical function immediately after strength training can last for 1-2 days in elderly depending on the type of physical function and intensity of training. Higher intensity resulted in greater impairment. Exercise prescription in elderly should take this into account, e.g., by gradually increasing intensity during the first months of strength training. These results have relevance for elderly who have to be fit for work or other activities in the days following strength training.
Publisher: American Physiological Society
Date: 05-2021
Abstract: Animal experiments and computational models have shown that motor neurons can lify the synaptic input they receive via persistent inward currents. Here we show in humans that this lification varies proportionally to the magnitude of the voluntary drive to the muscle.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2022
DOI: 10.1007/S00421-022-05101-3
Abstract: We tested two strategies that hypothetically increase serotonin availability (α-lactalbumin consumption and a remote submaximal handgrip contraction) on estimates of persistent inward currents (PICs) litude of soleus muscle in healthy participants. With a randomised, double-blind, and cross-over design, 13 healthy participants performed triangular-shaped r contractions with their plantar flexors (20% of maximal torque), followed by a 30-s handgrip sustained contraction (40% of maximal force) and consecutive repeated triangular-shaped contractions. This was performed before and after the consumption of either 40 g of α-lactalbumin, an isonitrogenous beverage (Zein) or an isocaloric beverage (Corn-starch). Soleus motor units discharge rates were analysed from high-density surface electromyography signals. PICs were estimated by calculating the delta frequency (ΔF) of motor unit train spikes using the paired motor unit technique. ΔF (0.19 pps p = 0.001 d = 0.30) and peak discharge rate (0.20 pps p < 0.001 d = 0.37) increased after the handgrip contraction, irrespective of the consumed supplement. No effects of α-lactalbumin were observed. Our results indicate that 40 g of α-lactalbumin was unable to modify intrinsic motoneuron excitability. However, performing a submaximal handgrip contraction before the plantar flexion triangular contraction was capable of increasing ΔF and discharge rates on soleus motor units. These findings highlight the diffused effects of serotonergic input, its effects on motoneuron discharge behaviour, and suggest a cross-effector effect within human motoneurons.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2022
DOI: 10.1007/S00421-022-05103-1
Abstract: The neurotransmitter serotonin has a strong effect on behaviour and motor control. Regarding motor control, serotonin contributes to the development of fatigue and is also involved in the ability of motor neurones to operate across a large range of forces (gain control). The consumption of tryptophan-rich supplements (such as α-lactalbumin) is of interest because this amino acid is the only precursor for brain serotonin synthesis. Therefore, the purpose of this study was to determine the effects of α-lactalbumin supplementation on neuromuscular performance. Using a randomised double-blind cross-over design, 16 healthy participants performed plantar flexor and handgrip maximal voluntary contractions, a 30-s submaximal handgrip contraction, and a plantar flexor fatigue protocol before and 90 min after consuming either 40 g of α-lactalbumin, an isonitrogenous beverage (Zein) or an isocaloric beverage (corn-starch). Sleepiness, mood, and cognition were assessed to evaluate any psychological effects. α-Lactalbumin decreased force steadiness by 25% during the sustained submaximal handgrip contraction (p < 0.01) and induced greater fatigue (15% reduction in total torque-time integral, p = 0.01) during the fatigue protocol. These effects were not observed for the other control beverages. No effects were found for maximal or explosive strength, or psychological measurements. 40 g of α-lactalbumin increased handgrip force variability and reduced performance during fatiguing muscle contractions but did not influence brief maximal contractions or psychological parameters in healthy in iduals. These findings support the hypothesis that the consumption of α-lactalbumin can increase motor neurone input-output gain and exacerbate central fatigue during sustained maximal exercise.
Publisher: Springer Science and Business Media LLC
Date: 17-05-2019
DOI: 10.1007/S40520-018-0970-5
Abstract: The interruption of training (detraining) results in loss of the gains acquired. Partial retention could occur after detraining, and variation in training stimuli may optimize retraining adaptations. To evaluate the effect of a resistance-retraining program on strength and functional capacity performance after a detraining period. Ten elderly men and women (63-68 years) completed 12 weeks of training, 16 weeks of detraining, and 8 weeks of retraining. One-repetition maximum (1-RM) at 45° leg press, maximum isometric knee extension torque, rate of torque development (RTD), 30-s sit-to-stand, timed up and go, and stair ascent and descent tests were assessed. The 1-RM increased after training (p < 0.01) and remained higher after a detraining period when compared to pre-training (p 0.05). For RTD and 30-s sit-to-stand, there was an increase after retraining when compared to pre-training values (p < 0.05). For timed up and go and stair ascent and descent, reductions were observed between pre-training and post-training periods (p < 0.05), only timed up and go increased after the detraining period (p < 0.01). After 16 weeks of detraining, the maximum strength did not return to baseline levels, and a retraining with explosive strength exercise sessions can recover maximum strength gains, RTD, and functional capacity at the same level obtained after a detraining period. The inclusion of an explosive strength session in retraining period improves RTD and 30-s sit-to-stand performance and can accelerate the recovery of strength after a detraining period.
Publisher: University Nove de Julho
Date: 04-12-2020
DOI: 10.5585/CONSSAUDE.V19N1.18247
Abstract: Objetivo: Verificar quais métodos de avaliação clínicos de força e potência muscular, e testes de desempenho físico funcionais estão correlacionados com o pico de torque isométrico e dinâmico dos extensores de joelho, e desenvolver equações preditivas que estimem o pico de torque isométrico e dinâmico em pessoas idosas. Métodos: Foram selecionados 49 sujeitos (≥ 60 anos) de ambos os sexos. O pico de torque muscular isométrico (PTISO) e dinâmico concêntrico (PTCON) dos extensores da articulação do joelho do membro preferido foi avaliado através de dinamômetro isocinético no primeiro dia de avaliação. Quarenta e oito horas depois o teste força máxima (1-RM) unilateral do membro preferido foi executado na cadeira extensora, seguindo do teste de potência do membro superior com uma medicine ball de 2 kg (ABM-2). No terceiro dia foram avaliados o teste de equilíbrio dinâmico (time up and go), a capacidade de subir e descer escadas (separadamente), com estes três testes foi construído um índice funcional (IFUNC). Resultados: Os principais resultados demonstraram que o IFUNC não prediz melhoria no pico de torque extensor do joelho (p0,05). Contrapondo a hipótese inicial que alterações no desempenho do pico de torque, tanto isométrico, como dinâmico, teria uma resposta direta com o desempenho funcional. Conclusão: As medidas de força máxima para membro inferior (cadeira extensora-1-RM) e potência de membro superior (arremesso da bola de medicine ball 2-kg) quando associadas explicam com mais de 60% (p0,05) uma mudança no desempenho na força isométrica e dinâmica dos extensores de joelho de idosos não treinados.
No related grants have been discovered for Lucas Bet da Rosa Orssatto.