Cross-education: motor unit adaptations mediate the strength increase in non-trained muscles following 8 weeks of unilateral resistance training

Frontiers in Physiology, Год журнала: 2025, Номер 15

Опубликована: Янв. 7, 2025

Early increases in muscle strength following unilateral resistance training are typically accompanied by gains the contralateral untrained muscles, a phenomenon known as cross-education. However, specific motor unit adaptations responsible for this gain transfer remain poorly understood. To address gap, we recorded myoelectrical activity from biceps brachii using high-density electromyography. Nine participants performed 8-week and were compared to nine control individuals who did no intervention. Discharge characteristics of longitudinally tracked units assessed during maximal voluntary contractions isometric ramp at 35% 70% force (MVF) baseline (T0), 4 weeks (T1), 8 (T2) post-intervention. MVF increased 7% muscles T1 10% T2 (p < 0.05). These significant decreases recruitment thresholds 0.01) higher net discharge rate (i.e., peak) intervention Trained presented greater (+11%, T1; +19%, T2) with similar adaptations, including lower threshold 0.01). Our findings indicate that is associated rate, implying spinal motoneuron output muscles. The present results underscore role non-trained offering novel insights into neural mechanisms underlying

Язык: Английский

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Sex differences in human performance

The Journal of Physiology, Год журнала: 2024, Номер 602(17), С. 4129 - 4156

Опубликована: Авг. 6, 2024

Sex as a biological variable is an underappreciated aspect of biomedical research, with its importance emerging in more recent years. This review assesses the current understanding sex differences human physical performance. Males outperform females many capacities because they are faster, stronger and powerful, particularly after male puberty. highlights key physiological anatomical systems (generally conferred via steroids puberty) that contribute to these Specifically, we address effects primary affect development, discuss insight gained from observational study 'real-world data' elite athletes, highlight mechanisms several aspects Physiological discussed include those for varying magnitude performance involving: (1) absolute muscular strength power; (2) fatigability limb muscles measure relative performance; (3) maximal aerobic power endurance. The profound sex-based involving strength, power, speed endurance, largely attributable direct indirect sex-steroid hormones, chromosomes epigenetics, provide scientific rationale framework policy decisions on categories sports during puberty adulthood. Finally, bias problem research insufficient studies information across areas biology physiology, creating knowledge gaps opportunities high-impact studies.

Язык: Английский

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Exercise-Specific Adaptations in Human Skeletal Muscle: Molecular Mechanisms of Making Muscles Fit and Mighty

Free Radical Biology and Medicine, Год журнала: 2024, Номер 223, С. 341 - 356

Опубликована: Авг. 13, 2024

The mechanisms leading to a predominantly hypertrophied phenotype versus oxidative phenotype, the hallmarks of resistance training (RT) or aerobic (AT), respectively, are being unraveled. In humans, exposure naïve persons either AT RT results in their skeletal muscle exhibiting generic 'exercise stress-related' signaling, transcription, and translation responses. However, with increasing engagement RT, responses become refined, typically associated each form exercise emerges. Here, we review some underpinning adaptations how muscles become, through AT, 'fit' 'mighty.' Much our understanding molecular physiology has arisen from targeted analysis post-translational modifications measures protein synthesis. Phosphorylation specific residue sites been dominant focus, canonical signaling pathways (AMPK mTOR) studied extensively context respectively. These alone, along synthesis, have only begun elucidate key differences signaling. Still, yet uncharacterized exist regulation synthesis that drive unique adaptation RT. Omic studies required better understand divergent relationship between phenotypic outcomes training.

Язык: Английский

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Salivary testosterone and cortisol responses to seven weeks of practical blood flow restriction training in collegiate American football players

Frontiers in Physiology, Год журнала: 2025, Номер 15

Опубликована: Янв. 8, 2025

The purpose of this study was to examine the effects a 7-week supplemental BFR training intervention on both acute and chronic alterations in salivary testosterone (sTes) cortisol (sCort) collegiate American football players. 58 males were divided into 4 groups: 3 completed an upper- lower-body split resistance routine (H, H/S, H/S/R; H = Heavy, S Supplemental, R BFR), with H/S/R performing end-of-session practical training, H/S serving as volume-matched non-BFR group. final group (M/S/R) modified programming same protocol H/S/R. Athletes further AM PM groups based upon their pre-determined schedules, cooperation University strength conditioning staff. Practical consisted barbell bench press back squat using 20% 1 repetition maximum (1RM) for 30-20-20-20 repetitions across sets, 45-seconds rest. Saliva samples taken pre- post- first sessions week 7 (i.e., test 2) program, yielding four total. sTes sCort analyzed 4-way (4 × 2 mixed model ANOVA's. Hormonal variables all exhibited main time-of-day (p < 0.001). A significant time interaction effect (F3,50 3.246, p 0.05) indicated increases post-training cycle only. Further, post-exercise decreased from (nmol·L-1: 95% CI: 10.7-17.1, 5.0-8.9). For testosterone-to-cortisol ratio (T/C), pre-exercise lower than 0.05), no change T/C conditions when collapsed testing times. Overall, these findings suggest ecologically valid method implementation is capable inducing heightened concentrations well-resistance trained athletes, providing additional insight possible physiological mechanisms underpinning BFR's ability elicit beneficial muscle hypertrophy maximal adaptations performed during regimented programs. Additionally, notable rises T/C, null response observed post-program groups, possibly indicative positive adaptation.

Язык: Английский

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Comparable amino acid & intramuscular signalling responses following consumption of microflora compared to whey protein post-resistance exercise in young adults

Опубликована: Март 1, 2025

Язык: Английский

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Making the case for resistance training in improving vascular function and skeletal muscle capillarization

Frontiers in Physiology, Год журнала: 2024, Номер 15

Опубликована: Фев. 9, 2024

Through decades of empirical data, it has become evident that resistance training (RT) can improve strength/power and skeletal muscle hypertrophy. Yet, until recently, vascular outcomes have historically been underemphasized in RT studies, which is underscored by several exercise-related reviews supporting the benefits endurance on measures. Several lines evidence suggest large artery diameter blood flow velocity increase after a single bout exercise, these events are mediated vasoactive substances released from endothelial cells myofibers (e.g., nitric oxide). Weeks to months also basal limb arterial while lowering pressure. Although older investigations suggested reduces capillary density, this likely due most studies being cross-sectional nature. Critically, newer longitudinal contradicts findings, growing body mechanistic rodent human data capillarity related mechanical overload-induced In review, we will discuss methods used our laboratories others assess size/function characteristics. Next, groups examining responses exercise chronic paradigms. Finally, RT-induced mechanisms associated with acute outcomes.

Язык: Английский

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Resistance training-induced changes in muscle proteolysis and extracellular matrix remodeling biomarkers in the untrained and trained states

European Journal of Applied Physiology, Год журнала: 2024, Номер 124(9), С. 2749 - 2762

Опубликована: Апрель 23, 2024

Язык: Английский

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Methylome–proteome integration after late‐life voluntary exercise training reveals regulation and target information for improved skeletal muscle health

The Journal of Physiology, Год журнала: 2024, Номер 603(1), С. 211 - 237

Опубликована: Июль 26, 2024

Exercise is a potent stimulus for combatting skeletal muscle ageing. To study the effects of exercise on in preclinical setting, we developed combined endurance-resistance training mice called progressive weighted wheel running (PoWeR). PoWeR improves molecular, biochemical, cellular and functional characteristics promotes aspects partial epigenetic reprogramming when performed late life (22-24 months age). In this investigation, leveraged pan-mammalian DNA methylome arrays tandem mass-spectrometry proteomics to provide detailed information late-life adaptations female relative age-matched sedentary controls (n = 7-10 per group). Differential CpG methylation at conserved promoter sites was related transcriptional regulation genes as well Nr4a3, Hes1 Hox after PoWeR. Using holistic method -omics integration binding expression target analysis (BETA), changes were associated with upregulated proteins global mitochondrial translation (P 0.03). Specifically, BETA implicated control ribosomal, mitoribosomal, complex I protein abundance training. may also influence LACTB, MIB1 UBR4 induction - all are mechanistically linked health. Computational cistrome predicted several transcription factors including MYC regulators trained methylome-proteome landscape, corroborating prior transcriptome data. Correlating proteome mass fatigue resistance revealed positive relationships VPS13A NPL levels, respectively. Our findings expose differential proteomic translational that could function aged mice. KEY POINTS: Late-life from 22-24 age shown improve vivo promote mitigation. Integration 36k using (which contain ageing clock sites) exploratory extends our work reveals coordinated widespread initiation, ribosomal (mitoribosomal) voluntary sizeable cohort group analysis). Multi-omics serine β-lactamase-like (LACTB tumour muscle), mind bomb 1 (MIB1 satellite cell type 2 fibre maintenance) ubiquitin ligase E3 component N-recognin 4 (UBR4 quality control) identified regulator proteome, agreement analyses. Vacuolar sorting 13 homolog A (VPS13A) positively correlated mass, glycoprotein/glycolipid sialylation enzyme N-acetylneuraminate pyruvate lyase (NPL) resistance.

Язык: Английский

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The utility of the rodent synergist ablation model in identifying molecular and cellular mechanisms of skeletal muscle hypertrophy

AJP Cell Physiology, Год журнала: 2024, Номер 327(3), С. C601 - C606

Опубликована: Июль 29, 2024

Skeletal muscle exhibits remarkable plasticity to adapt stimuli such as mechanical loading. The mechanisms that regulate skeletal hypertrophy due overload have been thoroughly studied. Remarkably, our understanding of many the molecular and cellular hypertrophic growth were first identified using rodent synergist ablation (SA) model subsequently corroborated in human resistance exercise training studies. To demonstrate utility SA model, we briefly summarize following translation these mechanism induced by training.

Язык: Английский

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The 24-hour molecular landscape after exercise in humans reveals MYC is sufficient for muscle growth

EMBO Reports, Год журнала: 2024, Номер unknown

Опубликована: Окт. 31, 2024

Язык: Английский

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