The molecular bases of training adaptation

Investigation of the effect of nitrate and L-arginine intake on aerobic, anaerobic performance, balance, agility, and recovery in elite taekwondo athletes

BACKGROUND

Taekwondo is a complex martial art that requires speed, balance, agility, and endurance. This study aims to examine the effects of nitrate and L-arginine supplementation on acute aerobic and anaerobic performance, balance, agility, and recovery in elite taekwondo athletes.

METHOD

This study was conducted as a double-blind, randomized, crossover study with the participation of 15 experienced taekwondo athletes aged 19.06 ± 0.96 years and 8.93 ± 1.27 years of training experience. Participants visited the laboratory a total of nine times, including a practice session and anthropometric measurements. These visits consisted of eight experimental sessions conducted at 72-hour intervals. The experimental sessions were conducted with nitrate, L-arginine, and a combination of both supplements (NIT*L-ARG) and placebo. Nitrate supplementation was provided by homogenizing fresh spinach (837.40 mg/kg), while L-ARG was given as a single dose of 6 g in powder form three hours before exercise.

RESULTS

NIT*L-ARG supplementation significantly improved the anaerobic performance of athletes in Wingate peak power and peak power (w/kg) compared to placebo and in mean power compared to NIT, L-ARG, and PLA. In addition, NIT*L-ARG supplementation significantly improved blood lactate levels and agility performance immediately after Wingate and Shuttle run tests.

CONCLUSION

The combined intake of NIT*L-ARG was found to be effective in improving aerobic, anaerobic, and agility performances as well as fatigue levels of athletes. It was determined that taking NIT and L-ARG supplements alone contributed to the improvement of improving athletes' performance in Wingate mean power values and subsequent fatigue level compared to PLA.

Impact of resistance and high-intensity interval training on body composition, physical function, and temporal dynamics of adaptation in older women with impaired cardiometabolic health: a randomized clinical trial

PURPOSE

Physical inactivity is associated with reduced physical fitness (PF) in older women with impaired cardiometabolic health. Although exercise has been shown to improve PF, interindividual variability in response and adaptation changes over time remain unclear. This study evaluated the effects of eight weeks of resistance training (RT) and high-intensity interval training (HIIT) on body composition, isometric strength, and the 6-minute walk test (6MWT) in older women with impaired cardiometabolic health. Additionally, the study explored the reduction of non-responders (NRs) and adaptation changes over time.

METHODS

This randomized clinical trial involved 36 older women (64 ± 8.4 years; BMI: 31.8 ± 5.5) with impaired cardiometabolic health, divided into RT-G (n = 12; 62 ± 7 years; BMI: 32.2 ± 4.1), HIIT-G (n = 12; 66 ± 10 years; BMI: 31.2 ± 4.1), and CG (n = 12; 64 ± 9 years; BMI: 31.8 ± 6) groups. RT-G performed elastic band exercises, and HIIT-G performed cycle ergometer intervals. BMI, body fat, lean mass, isometric strength, and 6MWT were measured at baseline and at four and eight weeks. The Student's t-test was applied for normally distributed variables and the Mann-Whitney U test for non-normal variables. Intra- and inter-group differences were analyzed using a two-way repeated measures ANOVA, considering group, time, and their interaction. Post-hoc comparisons were conducted using the Bonferroni test. Individual responses (IR) were calculated using the equation proposed by Hopkins: SDIR = √(SDExp2 - SDCon2). The prevalence of responders (Rs) and non-responders (NRs) was expressed as a percentage, and percentage changes from baseline to weeks four and eight were used to evaluate adaptations dynamics.

RESULTS

By week eight, isometric strength in RT-G significantly improved from 21.3 ± 4.4 to 24.37 ± 3.99 kg (p = 0.027; 95% CI: 1.8, 4.3 kg; Cohen's d = 0.731) and 6MWT distance in HIIT-G increased from 441.0 ± 48.9 to 480.0 ± 53.0 m. (p = 0.002; 95% CI: 22, 55 m; Cohen's d = 0.757). Both protocols reduced NRs for body fat, lean mass, and 6MWT. Responders showed greater adaptations in the first four weeks, stabilizing by week eight.

CONCLUSION

RT and HIIT improved PF in older women with impaired cardiometabolic health, reducing NRs in terms of body composition and 6MWT over eight weeks, with similar adaptation changes over time among the responders. These findings highlight the importance of individualized exercise interventions to maximize health benefits.

TRIAL REGISTRATION

This study was part of a trial registered at ClinicalTrials.gov (ID: NCT06201273). Date: 22/12/2023.

Using markerless motion analysis to quantify sex and discipline differences in external mechanical work during badminton match play

The high prevalence of overuse injuries in badminton poses a major threat to player development and success, with current training 'load' metrics insufficient for capturing the physical demands. This study quantified the external mechanical work performed during badminton match play across different sexes and disciplines. An eight-camera system captured fourteen male and fourteen female competitive (University to national level) badminton players competing across a total of nine singles and six doubles matches. Markerless pose estimation (HRNet) was used to drive a kinematic model (OpenSim) of each player and compute mass-normalised external mechanical work and power for 30 points per match. A linear mixed effects model found normalised work and power to be greater in men's vs. women's matches (effect size [ES] ± 90% CI = 0.60 ± 0.29 and 1.10 ± 0.48, respectively). Normalised work and power were also greater in singles vs. doubles matches (ES = 0.44 ± 0.29 and 0.47 ± 0.44, respectively). Interestingly, discipline differences were greatest among the most skilled players (e.g. ES = 0.88 ± 0.49 for first-team males). These findings highlight the importance of additional strength training and adequate recovery for elite male players to manage the high physical demands of singles match play.

Polarized or threshold training: is there a superior training intensity distribution to improve V̇O2max, endurance capacity and mitochondrial function? A study in Wistar Rat models

Conflicting evidence exists regarding the superiority of Polarized Training (POL) vs other training intensity distribution models. Compare POL vs threshold (THR) training on V̇O2max, endurance capacity (EC) and mitochondrial function. Fifteen male Wistar rats (336.1 ± 30.4 g) were divided in: POL (n = 5), THR (n = 5) or control (CON; n = 5) groups. V̇O2max (indirect calorimetry) and EC (treadmill exhaustion test) were determined at baseline four and eight-weeks of training. POL consisted of 80% running volume at 60%V̇O2max and 20% at 90%V̇O2max while THR trained only at 75%V̇O2max. Both protocols were isocaloric and performed 5d/week. All animals were housed in cages with access to running wheel to allow ad libitum activity. After training, animals were sacrificed and left ventricle (LV) myocardium, diaphragm, tibialis anterior and soleus muscles were collected for high-resolution respirometry, biochemical and histological analysis. There were no baseline differences between groups. After training V̇O2max and EC were similar between POL and THR even though THR V̇O2max was higher compared to CON. After training, there were also no significant differences in OXPHOS or any of the other major mitochondrial function markers assessed between POL and THR in any of the tissues analyzed. The expression of MFN1, MFN2, PGC-1α, TFAM, DRP1, OPA1 and TOM20 as well as the activity of citrate synthase were also similar between POL and THR in all tissues. There were no significant differences in endurance performance or markers of bioenergetic function between POL and THR after eight-weeks of training.

Effects of blood flow restriction training in athletes: a systematic review and meta-analysis

This systematic review and meta-analysis evaluated the effects of blood flow restriction training on strength and aerobic capacity in athletes, examining how training variables and participant characteristics influenced outcomes. Four databases were searched for peer-reviewed English-language studies, and the risk of bias and the quality of evidence were assessed using RoB 2 and GRADEpro GDT. We evaluated pre- and post-test differences by a three-level meta-analysis using meta and metafor packages. Subgroup analyses and both linear and nonlinear meta-regression methods were used to explore moderating factors. Sixteen studies with "some concerns," the risk of bias and low evidence level, were included. Combining blood flow restriction with low-intensity resistance training produced an effect size of 0.25 for strength, while combining blood flow restriction with aerobic training had an effect size of 0.42. For aerobic capacity, the effect size of combining blood flow restriction with aerobic training was 0.58. Subgroup and regression analyses showed no significant differences. While blood flow restriction with low-intensity resistance training enhances strength, it does not result in additional gains. Combining blood flow restriction with aerobic training enhances both the strength and the aerobic capacity. Overall, blood flow restriction appears to offer the most benefits for male athletes in improving the strength and aerobic capacity.

Muscle-Inspired Self-Growing Anisotropic Hydrogels with Mechanical Training-Promoting Mechanical Properties

Muscles are highly anisotropic, force-bearing issues. They form via a process involving nutrient absorption for matrix growth and mechanical training for matrix toughening, in which cyclic disassembly-reconstruction of muscle fibers plays a critical role in generating strong anisotropic structures. Inspired by this process, a mechanical training-associated growing strategy is developed for preparing tough anisotropic hydrogels. Using anisotropic hydrogels made from polyvinyl alcohol (PVA)/tannic acid (TA) as an example, it is demonstrated that the hydrogels can absorb poly(ethylene glycol) diacrylate (PEGDA) via disassembling their aligned nanofibrillar structures. Incorporation of PEGDA within the hydrogels induces PVA to form crystal domains while subsequent mechanical training can restore the aligned fibrillar structures. Such a combining process results in expansion in materials' size (≈2 times) and significant enhancement in their mechanical properties (Young's modulus: from 2.4 to 2.85 MPa; ultimate tensile strength: from 8.2 to 14.1 MPa; toughness: from 335 to 465 MJ m-3). With a high energy dissipation efficiency (≈0%), potential applications for these tough and adaptable hydrogels are envisioned in impact-protective materials, surgical sutures, etc.

Nutritional Interventions to Attenuate Quadriceps Muscle Deficits following Anterior Cruciate Ligament Injury and Reconstruction

Following anterior cruciate ligament (ACL) injury, quadriceps muscle atrophy persists despite rehabilitation, leading to loss of lower limb strength, osteoarthritis, poor knee joint health and reduced quality of life. However, the molecular mechanisms responsible for these deficits in hypertrophic adaptations within the quadriceps muscle following ACL injury and reconstruction are poorly understood. While resistance exercise training stimulates skeletal muscle hypertrophy, attenuation of these hypertrophic pathways can hinder rehabilitation following ACL injury and reconstruction, and ultimately lead to skeletal muscle atrophy that persists beyond ACL reconstruction, similar to disuse atrophy. Numerous studies have documented beneficial roles of nutritional support, including nutritional supplementation, in maintaining and/or increasing muscle mass. There are three main mechanisms by which nutritional supplementation may attenuate muscle atrophy and promote hypertrophy: (1) by directly affecting muscle protein synthetic machinery; (2) indirectly increasing an individual's ability to work harder; and/or (3) directly affecting satellite cell proliferation and differentiation. We propose that nutritional support may enhance rehabilitative responses to exercise training and positively impact molecular machinery underlying muscle hypertrophy. As one of the fastest growing knee injuries worldwide, a better understanding of the potential mechanisms involved in quadriceps muscle deficits following ACL injury and reconstruction, and potential benefits of nutritional support, are required to help restore quadriceps muscle mass and/or strength. This review discusses our current understanding of the molecular mechanisms involved in muscle hypertrophy and disuse atrophy, and how nutritional supplements may leverage these pathways to maximise recovery from ACL injury and reconstruction.

The effect of exercise and physical activity on skeletal muscle epigenetics and metabolic adaptations

Physical activity (PA) and exercise elicit adaptations and physiological responses in skeletal muscle, which are advantageous for preserving health and minimizing chronic illnesses. The complicated atmosphere of the exercise response can be attributed to hereditary and environmental variables. The primary cause of these adaptations and physiological responses is the transcriptional reactions that follow exercise, whether endurance- (ET) or resistance- training (RT). As a result, the essential metabolic and regulatory pathways and myogenic genes associated with skeletal muscle alter in response to acute and chronic exercise. Epigenetics is the study of the relationship between genetics and the environment. Exercise evokes signaling pathways that strongly alter myofiber metabolism and skeletal muscle physiological and contractile properties. Epigenetic modifications have recently come to light as essential regulators of exercise adaptations. Research has shown various epigenetic markers linked to PA and exercise. The most critical epigenetic alterations in gene transcription identified are DNA methylation and histone modifications, which are associated with the transcriptional response of skeletal muscle to exercise and facilitate the modification to exercise. Other changes in the epigenetic markers are starting to emerge as essential processes for gene transcription, including acetylation as a new epigenetic modification, mediated changes by methylation, phosphorylation, and micro-RNA (miRNA). This review briefly introduces PA and exercise and associated benefits, provides a summary of epigenetic modifications, and a fundamental review of skeletal muscle physiology. The objectives of this review are 1) to discuss exercise-induced adaptations related to epigenetics and 2) to examine the interaction between exercise metabolism and epigenetics.

Zone 2 Intensity: A Critical Comparison of Individual Variability in Different Submaximal Exercise Intensity Boundaries

Introduction: Endurance athletes often utilize low-intensity training, commonly defined as Zone 2 (Z2) within a five-zone intensity model, for its potential to enhance aerobic adaptations and metabolic efficiency. This study aimed at evaluating intra- and interindividual variability of commonly used Z2 intensity markers to assess their precision in reflecting physiological responses during training. Methods: Fifty cyclists (30 males and 20 females) performed both an incremental ramp and a step test in a laboratory setting, during which the power output, heart rate, blood lactate, ventilation, and substrate utilization were measured. Results: Analysis revealed substantial variability in Z2 markers, with the coefficients of variation (CV) ranging from 6% to 29% across different parameters. Ventilatory Threshold 1 (VT1) and maximal fat oxidation (FatMax) showed strong alignment, whereas fixed percentages of HRmax and blood lactate thresholds exhibited wide individual differences. Discussion: Standardized markers for Z2, such as fixed percentages of HRmax, offer practical simplicity but may inaccurately reflect metabolic responses, potentially affecting training outcomes. Given the considerable individual variability, particularly in markers with high CVs, personalized Z2 prescriptions based on physiological measurements such as VT1 and FatMax may provide a more accurate approach for aligning training intensities with metabolic demands. This variability highlights the need for individualized low-intensity training prescriptions to optimize endurance adaptations in cyclists, accommodating differences in physiological profiles and improving training specificity.

Weak Covalent Bonds and Mechanochemistry for Synergistic Self-Strengthening of Elastomers

The macroscopic properties of elastomers are intimately linked to their molecular reactivity and mechanisms. Here, we propose a new strategy for designing strengthening materials based on the synergy of weak covalent bonds and mechanochemistry. After mechanical treatment, the failure strength and toughness of the elastomer increased from 2.37 ± 0.05 MPa and 11.34 ± 0.30 MJ/m3 to 6.02 ± 0.04 MPa and 18.40 ± 0.30 MJ/m3, respectively, while maintaining excellent tensile properties. Notably, experimental tests, theoretical calculations, and small-molecule reaction model results show that the sulfur-carbon bond is more prone to homolysis, and the reactive sites are between sulfur radicals and the end-positioned carbon of the vinyl. The C-S weak bond of spirothiopyran (STP) first undergoes homolysis to dissipate energy suffering from external stress, and the radical-mediated click reaction leads to the interchain cross-linking, thus enhancing the mechanical strength. In the end, the prepared elastomer is further used to construct a photonic elastomer, which exhibits not only mechanical force-enhanced strength but also mechanochromism. The present work provides an opportunity for innovative design of self-strengthening materials, and the prepared novel self-strengthening elastomer has broad applications in visualized strain monitoring, electronic skin, soft robots, and other fields.

Prehabilitation during neoadjuvant therapy in patients with cancer of the upper gastrointestinal tract and rectum-the study protocol

Aims

The concept of prehabilitation, defined as interventions aimed at enhancing a patient's functional capacity prior to an impending physiological stressor, may contribute to reduced postoperative morbidity and mortality. The study's goal is to verify or refute the feasibility of a prehabilitation programme for two diagnostic patient groups during neoadjuvant chemo(radio)therapy, which is prescribed before the scheduled surgical procedure. This is a single group study design, with all patients enrolled receiving the intervention.

Methods

This is an interventional feasibility study of a prehabilitation programme in the form of physical training conducted at home. The training consists of progressively dosed walking and strength exercises for selected muscle groups. Data will be monitored telemetrically and also through telephone contact with participants. Primary outcomes include: the percentage of patients interested in participating in the study out of all patients indicated for neoadjuvant therapy at University Hospital Ostrava during the observed period, the percentage of patients who complete the prehabilitation programme until the date of surgery and individual patient compliance. Secondary outcomes include physical fitness parameters obtained from cardiopulmonary exercise testing, grip strength measured by a dynamometer, changes in body composition, EORTC QLQ-C30 quality of life questionnaire, and a questionnaire on the subjective perception of the exercise programme. Both primary and secondary outcomes will be compared between study arms (two diagnostic groups). The study is registered at ClinicalTrials.gov, ID: NCT05646043.

Conclusion

The results of this study can serve as a foundation for larger, multicentre, controlled studies in the future.

A window into intracellular events in myositis through subcellular proteomics

OBJECTIVE AND DESIGN

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of inflammatory muscle disorders of unknown etiology. It is postulated that mitochondrial dysfunction and protein aggregation in skeletal muscle contribute to myofiber degeneration. However, molecular pathways that lead to protein aggregation in skeletal muscle are not well defined.

SUBJECTS

Here we have isolated membrane-bound organelles (e.g., nuclei, mitochondria, sarcoplasmic/endoplasmic reticulum, Golgi apparatus, and plasma membrane) from muscle biopsies of normal (n = 3) and muscle disease patients (n = 11). Of the myopathy group, 10 patients displayed mitochondrial abnormalities (IIM (n = 9); mitochondrial myopathy (n = 1)), and one IIM patient did not show mitochondrial abnormalities (polymyositis).

METHODS

Global proteomic analysis was performed using an Orbitrap Fusion mass spectrometer. Upon unsupervised clustering, normal and mitochondrial myopathy muscle samples clustered separately from IIM samples.

RESULTS

We have confirmed previously known protein alterations in IIM and identified several new ones. For example, we found differential expression of (i) nuclear proteins that control cell division, transcription, RNA regulation, and stability, (ii) ER and Golgi proteins involved in protein folding, degradation, and protein trafficking in the cytosol, and (iii) mitochondrial proteins involved in energy production/metabolism and alterations in cytoskeletal and contractile machinery of the muscle.

CONCLUSIONS

Our data demonstrates that molecular alterations are not limited to protein aggregations in the cytosol (inclusions) and occur in nuclear, mitochondrial, and membrane compartments of IIM skeletal muscle.

Muscle Strength and Size Relationships with Unilateral Progressive Resistance Training

Purpose

This study defines correlative and causal relationships between muscle strength and size before and after unilateral resistance training (RT) in a large cohort of healthy adults, focusing on sex differences within these relationships.

Methods

Results from 1233 participants (504 males and 729 females) in a retrospective analysis were included. Maximal voluntary isometric contraction strength (MVC), one-repetition maximum strength (1RM), biceps cross-sectional area (CSA) and elbow flexor volume (VOL) measures of the non-dominant and dominant arm were evaluated from baseline and after 12-wk RT twice per week. Correlations of MVC and VOL and 1RM and VOL were calculated in the whole cohort and within each sex independently. Causal analysis modeling was used to infer mechanistic relationships among variables.

Results

Absolute muscle strength and size related to one another both at baseline and following training, however correlation strength in each sex were weak. After RT, MVC relative change and VOL relative change correlations were correlated for the whole cohort (r=0.16; p<0.001) and females (r=0.18; p<0.001), but not in males (r=0.11; p=0.07). No significant correlations for relative change in 1RM and VOL were observed for the whole cohort or within sex. Causal discovery determined that change in VOL caused significant change in 1RM (but not MVC) and age was identified as a potential cause.

Conclusions

Sex differences occur in muscle size and strength relationship adaptations following resistance training, most notably the absence of significant relationships between relative size and strength changes in men. Simpson's paradox bias, where assessing the combined data of males and females (also affecting overall sample size) affects identifies patterns differently than assessing relationships within each sex, may partially explain our findings.

Could Motor Imagery Training Provide a Novel Load Management Solution for Athletes? Recommendations for Sport Medicine and Performance Practitioners

CONTEXT

Athletes often face the dual challenge of high training loads with insufficient time to recover. Equally, in any team, sports medicine and performance staff are required to progress training loads in healthy athletes and avoid prolonged reductions in training load in injured athletes. In both cases, the implementation of a well-established psychological technique known as motor imagery (MI) can be used to counteract adverse training adaptations such as excessive fatigue, reduced capacity, diminished performance, and heightened injury susceptibility.

STUDY DESIGN

Narrative overview.

LEVEL OF EVIDENCE

Level 5.

RESULTS

MI has been shown to enhance performance outcomes in a range of contexts including rehabilitation, skill acquisition, return-to-sport protocols, and strength and conditioning. Specific performance outcomes include reduction of strength loss and muscular atrophy, improved training engagement of injured and/or rehabilitating athletes, promotion of recovery, and development of sport-specific skills/game tactics. To achieve improvements in such outcomes, it is recommended that practitioners consider the following factors when implementing MI: individual skill level (ie, more time may be required for novices to obtain benefits), MI ability (ie, athletes with greater capacity to create vivid and controllable mental images of their performance will likely benefit more from MI training), and the perspective employed (ie, an internal perspective may be more beneficial for increasing neurophysiological activity whereas an external perspective may be better for practicing technique-focused movements).

CONCLUSION

We provide practical recommendations grounded in established frameworks on how MI can be used to reduce strength loss and fear of reinjury in athletes with acute injury, improve physical qualities in rehabilitating athletes, reduce physical loads in overtrained athletes, and to develop tactical and technical skills in healthy athletes.

Too old for healthy aging? Exploring age limits of longevity treatments

It is well documented that aging elicits metabolic failures, while poor metabolism contributes to accelerated aging. Metabolism in general, and energy metabolism in particular are also effective entry points for interventions that extend lifespan and improve organ function during aging. In this review, we discuss common metabolic remedies for healthy aging from the angle of their potential age-specificity. We demonstrate that some well-known metabolic treatments are mostly effective in young and middle-aged organisms, while others maintain high efficacy independently of age. The mechanistic basis of presence or lack of the age limitations is laid out and discussed.

Preworkout dietary nitrate magnifies training-induced benefits to physical function in late postmenopausal women: a randomized pilot study

To inform end points for future work, we explored the utility of preworkout (i.e., an acute dose before training) beetroot juice (BRJ) combined with exercise (BRJ + EX) to augment indices of physical function in postmenopausal women compared with exercise only (EX). A two-arm pilot study was used to compare 24 postmenopausal women following an 8-wk, circuit-based exercise intervention. Participants were randomized to BRJ + EX (n = 12) or EX (n = 12). BRJ + EX participants consumed 140 mL of BRJ 120-180 min (only) before training for 7 wk, then discontinued during the final week to mitigate carryover effects. Physical function indices were 6-min walk test (6MWT), estimated V̇o2peak, heart rate recovery (HRR), and maximal knee extensor power (Pmax). A treadmill task was used to measure V̇o2 on-kinetics wherein mean response time (MRT) coincided with the duration to reach 63% of steady-state V̇o2. Results showed greater changes (Δ) among BRJ + EX participants for 6MWT distance (40 ± 23 m vs. 8 ± 25 m; P = 0.003, d = 1.35), ΔV̇o2peak (1.5 ± 0.9 mL·kg-1·min-1 vs. 0.3 ± 1.0 mL·kg-1·min-1; P = 0.008, d = 1.20), and ΔHRR (-10 ± 6 beats/min vs. -1 ± 9 beats/min; P = 0.017, d = 1.05). Large and medium effect sizes favoring BRJ + EX were detected for ΔPmax (P = 0.07, d = 0.83) and ΔMRT (P = 0.257, d = 0.50), respectively. In postmenopausal women, BRJ + EX appears to magnify some adaptive benefits to physical function including aerobic capacity and recovery beyond that of training without BRJ. Investigation into contributing mechanisms is needed.NEW & NOTEWORTHY Though exercise training represents the principal strategy to combat age-related decline, the attendant effects of menopause weaken aspects of exercise adaptation compared with premenopausal women and age-matched men. Here we provide important initial evidence that preworkout (i.e., an acute dose before training) beetroot juice coupled with an 8-wk, circuit-based exercise training intervention may uniquely benefit late postmenopausal women by enhancing indices of physical function including aerobic capacity and recovery.

Polarized running training adapted to versus contrary to the menstrual cycle phases has similar effects on endurance performance and cardiovascular parameters

PURPOSE

This study compared the effects of polarized running training adapted to the menstrual cycle (MC) phases versus polarized training adapted contrary to the MC on endurance performance and cardiovascular parameters.

METHODS

Thirty-three naturally menstruating, moderately trained females (age: 26 ± 4 years; BMI: 22.3 ± 3.2 kg/m2; V ˙ O2max/rel: 40.35 ± 4.61 ml/min/kg) were randomly assigned to a control (CON) and intervention (INT) group. Both groups participated in a load-matched eight-week running training intervention. In the INT, high-intensity sessions were aligned with the mid and late follicular phase, low-intensity sessions with the early and mid-luteal phase, and recovery with the late luteal and early follicular phase. In the CON, high-intensity sessions were matched to the late luteal and early follicular phase, and recovery to the mid and late follicular phase. Endurance performance and cardiovascular parameters were assessed at baseline and after the intervention.

RESULTS

Twenty-six females completed the intervention. A repeated measures ANOVA determined no time × group interaction effect for any parameter. A significant time effect was found for maximal oxygen uptake (F(1,12) = 18.753, p = 0.005, ηp2 = 0.630), the velocity at the ventilatory threshold one (F(1,12) = 10.704, p = 0.007, ηp2 = 0.493) and two (F(1,12) = 7.746, p = .018, ηp2 = .413).

CONCLUSION

The training intervention improved endurance performance in both groups, with no further benefit observed from the MC-adapted polarized training in a group-based analysis. Replications with an extended intervention period, a larger sample size, and a more reliable MC determination are warranted.

Autophagy Alterations in White and Brown Adipose Tissues of Mice Exercised under Different Training Protocols

BACKGROUND

Autophagy is a conserved catabolic process that promotes cellular homeostasis and health. Although exercise is a well-established inducer of this pathway, little is known about the effects of different types of training protocols on the autophagy levels of tissues that are tightly linked to age-related metabolic syndromes (like brown adipose tissue) but are not easily accessible in humans.

METHODS

Here, we take advantage of animal models to assess the effects of short- and long-term resistance and endurance training in both white and brown adipose tissue, reporting distinct alterations on autophagy proteins microtubule-associated proteins 1A/1B light chain 3B (MAP1LC3B, or LC3B) and sequestosome-1 (SQSTM1/p62). Additionally, we also analyzed the repercussions of these interventions in fat tissues of mice lacking autophagy-related protein 4 homolog B (ATG4B), further assessing the impact of exercise in these dynamic, regulatory organs when autophagy is limited.

RESULTS

In wild-type mice, both short-term endurance and resistance training protocols increased the levels of autophagy markers in white adipose tissue before this similarity diverges during long training, while autophagy regulation appears to be far more complex in brown adipose tissue. Meanwhile, in ATG4B-deficient mice, only resistance training could slightly increase the presence of lipidated LC3B, while p62 levels increased in white adipose tissue after short-term training but decreased in brown adipose tissue after long-term training.

CONCLUSIONS

Altogether, our study suggests an intricated regulation of exercise-induced autophagy in adipose tissues that is dependent on the training protocol and the autophagy competence of the organism.

Impact of a Pilates intervention on physical function in children with generalised joint hypermobility and chronic musculoskeletal pain: A single-case experimental design

AIM

To assess the impact of a Physiotherapist-led Pilates Intervention for school aged children with Generalised Joint Hypermobility (GJH) on pain, physical function and Health Related Quality of Life (HRQoL).

METHODS

Three children aged 8-12 years with GJH participated in an 8 week Physiotherapist-led Pilates Intervention within a single-case experimental design (multiple baseline design). Repeated measures were collected during baseline, intervention, withdrawal and follow-up, for: (i) pain, (ii) physical function as measured by muscle strength, postural control, fatigue and activity levels and (iii) HRQoL.

RESULTS

Within the intervention phase, two children showed reduced fatigue and one child improved in muscle group strength of hip abduction (gluteus medius) and scapula adduction/rotation (rhomboideus major/minor) and HRQoL. No improvements were seen in pain or postural control. Within the early withdrawal phase all children showed improved strength for at least two muscle groups and one child showed reduced fatigue, pain (worst in last week) and improved postural control (functional reach lateral).

CONCLUSIONS

Pilates may provide an effective intervention for children with GJH to reduce fatigue and improve muscle strength and HRQoL. Limited conclusions can be made regarding pain and postural control. Further research with a longer Pilates duration is needed to confirm the dose and benefits for this population.

Response of Circulating Free Cellular DNA to Repeated Exercise in Men with Type 1 Diabetes Mellitus

Background: Intense exercise leads to neutrophil extracellular traps (NETs) formation, which triggers cell disintegration. NET, as well as other processes of apoptosis, necrosis, and spontaneous secretion, result in increased levels of cell-free DNA (cf-DNA) in the circulation. An increment of cf-DNA is also observed in autoimmune diseases, such as type 1 diabetes mellitus (T1DM). Repeated exhaustive exercises are an impulse for physiological adaptation; therefore, in this case-control study, we compared the exercise-induced increase in cf-DNA in men with T1DM and healthy controls to determine the development of the tolerance to exercise. Methods: Volunteers performed a treadmill run to exhaustion at a speed matching 70% of their personal VO2 max at three consecutive visits, separated by a 72 h resting period. Blood was collected before and after exercise for the determination of plasma cell-free nuclear and mitochondrial DNA (cf n-DNA, cf mt-DNA) by real-time PCR, blood cell count and metabolic markers. Results: Each bout of exhaustive exercise induced a great elevation of cf n-DNA levels. An increase in cf mt-DNA was observed after each run. However, the significance of the increase was noted only after the second bout in T1DM participants (p < 0.02). Changes in cf-DNA concentration were transient and returned to baseline values during 72 h of resting. The exercise-induced increment in circulating cf n-DNA and cf mt-DNA was not significantly different between the studied groups (p > 0.05). Conclusions: Cf-DNA appears to be a sensitive marker of inflammation, with a lower post-exercise increase in individuals with T1DM than in healthy men.

Myostatin serum levels depends on age and diet in athletic and no athletic dogs

Myostatin is a growth factor related to muscular mass atrophy via mTOR pathway inhibition. Mutations in this gene have been correlated with high muscular mass development in different species of mammals, including human and dogs. Different studies have shown that sport practice increases myostatin gene expression. Some of them were conducted in canine breeds selected for different sport practices, including mushing sports. In this study, body weight, muscular mass, and serum levels of myostatin were analysed in different canine breeds, selected, and not selected for sprint and middle-distance racing, and the effect on epidemiological factors was evaluated. Sex, reproductive status, and canine breed affects body weight and muscular mass, being higher in males, and in sled canine breed. Age has an effect in body weight and myostatin serum levels, being lower in elder dogs. Sport practice and type of diet had an effect in muscular mass development but not in myostatin serum levels. Results showed a high positive correlation between muscular mass and body weight but not with myostatin levels. These results suggest that independent-myostatin mechanisms of mTOR pathway regulation could be related to muscular mass development in dogs.

Brain Evolution in the Times of the Pandemic and Multimedia

BACKGROUND

In this paper, we argue that recent unprecedented social changes arising from social media and the internet represent powerful behavioral and environmental forces that are driving human evolutionary adaptive responses in a way that might reshape our brain and the way it perceives reality and interacts with it. These forces include decreases in physical activity, decreases in exposure to light, and face-to-face social interactions, as well as diminished predictability in biological rhythms (i.e., the sleep cycle is no longer dictated by natural light exposure and season).

SUMMARY

We discuss the roles of stress and of creativity and adaptability in Homo sapiens evolution and propose mechanisms for human adaptation to the new forces including epigenetic mechanisms, gene-culture coevolution, and novel mechanisms of evolution of the nervous system.

KEY MESSAGES

We present the provocative idea that evolution under the strong selective pressures of today's society could ultimately enable H. sapiens to thrive despite social, physical, circadian, and cultural deprivation and possible neurological disease, and thus withstand the loss of factors that contribute to H. sapiens survival of today. The new H. sapiens would flourish under a lifestyle in which the current form would feel undervalued and replaceable.

Exercise-induced response of proteinogenic and non-proteinogenic plasma free amino acids is sport-specific: A comparison of sprint and endurance athletes

Circulating blood is an important plasma free amino acids (PFAAs) reservoir and a pivotal link between metabolic pathways. No comparisons are available between athletes with opposite training adaptations that include a broader spectrum of both proteinogenic and non-proteinogenic amino acids, and that take into account skeletal muscle mass. We hypothesized that the levels of the exercise-induced PFAAs concentration are related to the type of training-related metabolic adaptation. We compared highly trained endurance athletes (n = 11) and sprinters (n = 10) aged 20‒35 years who performed incremental exercise until exhaustion. Venous blood was collected before and during the test and 30-min recovery (12 samples). Forty-two PFAAs were assayed using LC-ESI-MS/MS technique. Skeletal muscle mass was estimated using dual X-ray absorptiometry method. Glutamine and alanine were dominant PFAAs throughout the whole exercise and recovery period (~350‒650 μmol∙L-1). Total, combined proteinogenic, non-essential, and non-proteinogenic PFAAs levels were significantly higher in endurance athletes than sprinters (ANOVA group effects: p = 0.007, η2 = 0.321; p = 0.011, η2 = 0.294; p = 0.003, η2 = 0.376; p = 0.001, η2 = 0.471, respectively). The exercise response was more pronounced in endurance athletes, especially for non-proteinogenic PFAAs (ANOVA interaction effect: p = 0.038, η2 = 0.123). Significant between-group differences were observed for 19 of 33 PFAAs detected, including 4 essential, 7 non-essential, and 8 non-proteinogenic ones. We demonstrated that the PFAAs response to incremental aerobic exercise is associated with the type of training-related metabolic adaptation. A greater turnover and availability of circulating PFAAs for skeletal muscles and other body tissues is observed in endurance- than in sprint-trained individuals. Non-proteinogenic PFAAs, despite low concentrations, also respond to exercise loads, indicating their important, though less understood role in exercise metabolism. Our study provides additional insight into the exercise-induced physiological response of PFAAs, and may also provide a rationale in discussions regarding dietary amino acid requirements in high-performance athletes with respect to sports specialization.

Comprehensive Genetic Analysis of Associations between Obesity-Related Parameters and Physical Activity: A Scoping Review

Genetic epidemiological studies have shown that numerous genetic variants cumulatively increase obesity risk. Although genetically predisposed individuals are more prone to developing obesity, it has been shown that physical activity can modify the genetic predisposition to obesity. Therefore, genetic data obtained from earlier studies, including 30 polymorphisms located in 18 genes, were analyzed using novel methods such as the total genetic score and Biofilter 2.4 software to combine genotypic and phenotypic information for nine obesity-related traits measured before and after the realization of the 12-week training program. The results revealed six genes whose genotypes were most important for post-training changes-LEP, LEPR, ADIPOQ, ADRA2A, ADRB3, and DRD2. Five noteworthy pairwise interactions, LEP × LEPR, ADRB2 × ADRB3, ADRA2A × ADRB3, ADRA2A × ADRB2, ADRA2A × DRD2, and three specific interactions demonstrating significant associations with key parameters crucial for health, total cholesterol (TC), high-density lipoprotein (HDL), and fat-free mass (FFM), were also identified. The molecular basis of training adaptation described in this study would have an enormous impact on the individualization of training programs, which, designed according to a given person's genetic profile, will be effective and safe intervention strategies for preventing obesity and improving health.

Effects of Exercise on DNA Methylation: A Systematic Review of Randomized Controlled Trials

BACKGROUND

Regular exercise reduces chronic disease risk and extends a healthy lifespan, but the underlying molecular mechanisms remain unclear. DNA methylation is implicated in this process, potentially altering gene expression without changing DNA sequence. However, previous findings appear partly contradictory.

OBJECTIVE

This review aimed to elucidate exercise effects on DNA methylation patterns.

METHODS

PubMed, Scopus and Web of Science databases were searched following PRISMA 2020 guidelines. All articles published up to November 2023 were considered for inclusion and assessed for eligibility using the PICOS (Population, Intervention, Comparison, Outcomes and Study) framework. Randomized controlled trials that assessed the impact of exercise interventions on DNA methylation in previously inactive adults were included. We evaluated the methodological quality of trials using the PEDro scale.

RESULTS

A total of 852 results were identified, of which 12 articles met the inclusion criteria. A total of 827 subjects were included in the studies. Intervention lengths varied from 6 weeks to 12 months. Most trials indicated that exercise interventions can significantly alter the DNA methylation of specific genes and global DNA methylation patterns.

CONCLUSIONS

The heterogeneity of results may arise from differences in participant demographics, intervention factors, measurement techniques, and the genomic contexts examined. Future research should analyze the influences of activity type, intensity, and duration, as well as the physical fitness outcomes on DNA methylation. Characterizing such dose-response relationships and identifying genes responsive to exercise are crucial for understanding the molecular mechanisms of exercise, unlocking its full potential for disease prevention and treatment.

Discussing Conflicting Explanatory Approaches in Flexibility Training Under Consideration of Physiology: A Narrative Review

The mechanisms underlying range of motion enhancements via flexibility training discussed in the literature show high heterogeneity in research methodology and study findings. In addition, scientific conclusions are mostly based on functional observations while studies considering the underlying physiology are less common. However, understanding the underlying mechanisms that contribute to an improved range of motion through stretching is crucial for conducting comparable studies with sound designs, optimising training routines and accurately interpreting resulting outcomes. While there seems to be no evidence to attribute acute range of motion increases as well as changes in muscle and tendon stiffness and pain perception specifically to stretching or foam rolling, the role of general warm-up effects is discussed in this paper. Additionally, the role of mechanical tension applied to greater muscle lengths for range of motion improvement will be discussed. Thus, it is suggested that physical training stressors can be seen as external stimuli that control gene expression via the targeted stimulation of transcription factors, leading to structural adaptations due to enhanced protein synthesis. Hence, the possible role of serial sarcomerogenesis in altering pain perception, reducing muscle stiffness and passive torque, or changes in the optimal joint angle for force development is considered as well as alternative interventions with a potential impact on anabolic pathways. As there are limited possibilities to directly measure serial sarcomere number, longitudinal muscle hypertrophy remains without direct evidence. The available literature does not demonstrate the necessity of only using specific flexibility training routines such as stretching to enhance acute or chronic range of motion.

The effects of exercise on epigenetic modifications: focus on DNA methylation, histone modifications and non-coding RNAs

Physical activity on a regular basis has been shown to bolster the overall wellness of an individual; research is now revealing that these changes are accompanied by epigenetic modifications. Regular exercise has been proven to make intervention plans more successful and prolong adherence to them. When it comes to epigenetic changes, there are four primary components. This includes changes to the DNA, histones, expression of particular non-coding RNAs and DNA methylation. External triggers, such as physical activity, can lead to modifications in the epigenetic components, resulting in changes in the transcription process. This report pays attention to the current knowledge that pertains to the epigenetic alterations that occur after exercise, the genes affected and the resulting characteristics.

Effects of exercise modality combined with moderate hypoxia on blood glucose regulation in adults with overweight

Purpose: This study aimed to investigate the combined effects of moderate hypoxia with three different exercise modes on glucose regulation in healthy overweight adults. Methods: Thirteen overweight males (age: 31 ± 4 years; body fat 26.3 ± 3.2%) completed three exercise trials in a randomized crossover design involving 60 min cycling exercise at 90% lactate threshold (LOW), sprint interval training (20 × 4 s all-out; SIT) and lower limb functional bodyweight exercises (8 sets of 4 × 20 s; FEX) under moderate hypoxia (FiO2 = 16.5%). Post-exercise oral glucose tolerance test (OGTT) was performed following each trial. Heart rate, oxygen saturation (SpO2), physical activity enjoyment scale (PACES), and perceptual measures were recorded during each exercise session. Venous blood was collected pre-, immediately post-, and 24 h post-exercise and analysed for plasma glucose and insulin, incremental area under curve (iAUC), and circulating microRNA expression (c-miRs-486-5p, -126-5p, and -21-5p). Interstitial glucose concentrations were measured using continuous glucose monitoring (CGM). Results: Post-exercise OGTT iAUC for plasma glucose and insulin concentration were lower in SIT and LOW vs. control (p < 0.05) while post-exercise interstitial glucose iAUC and c-miRs were not different between exercise modes. Heart rate was greater in SIT vs. LOW and FEX, and FEX vs. LOW (p < 0.05), SpO2 was lower in SIT, while PACES was not different between exercise modes. Perceptual measures were greater in SIT vs. LOW and FEX. Conclusion: Acute SIT and LOW under moderate hypoxia improved post-exercise plasma insulin compared to FEX exercises. Considering SIT was also time-efficient, well tolerated, and enjoyable for participants, this may be the preferred exercise modality for improving glucose regulation in adult males with overweight when combined with moderate hypoxia.

Immunological regulation of skeletal muscle adaptation to exercise

Exercise has long been acknowledged for its powerful disease-preventing, health-promoting effects. However, the cellular and molecular mechanisms responsible for the beneficial effects of exercise are not fully understood. Inflammation is a component of the stress response to exercise. Recent work has revealed that such inflammation is not merely a symptom of exertion; rather, it is a key regulator of exercise adaptations, particularly in skeletal muscle. The purpose of this piece is to provide a conceptual framework that we hope will integrate exercise immunology with exercise physiology, muscle biology, and cellular immunology. We start with an overview of early studies in the field of exercise immunology, followed by an exploration of the importance of stromal cells and immunocytes in the maintenance of muscle homeostasis based on studies of experimental muscle injury. Subsequently, we discuss recent advances in our understanding of the functions and physiological relevance of the immune system in exercised muscle. Finally, we highlight a potential immunological basis for the benefits of exercise in musculoskeletal diseases and aging.

Relevance of Cardiovascular Exercise in Cancer and Cancer Therapy-Related Cardiac Dysfunction

PURPOSE OF THE REVIEW

Cancer therapy-related cardiac dysfunction (CTRCD) has been identified as a threat to overall and cancer-related survival. Although aerobic exercise training (AET) has been shown to improve cardiorespiratory fitness (CRF), the relationship between specific exercise regimens and cancer survival, heart failure development, and reduction of CTRCD is unclear. In this review, we discuss the impact of AET on molecular pathways and the current literature of sports in the field of cardio-oncology.

RECENT FINDINGS

Cardio-oncological exercise trials have focused on variations of AET intensity by using moderate continuous and high intensity interval training, which are applicable, safe, and effective approaches to improve CRF. AET increases CRF, reduces cardiovascular morbidity and heart failure hospitalization and should thus be implemented as an adjunct to standard cancer therapy, although its long-term effect on CTRCD remains unknown. Despite modulating diverse molecular pathways, it remains unknown which exercise regimen, including variations of AET duration and frequency, is most suited to facilitate peripheral and central adaptations to exercise and improve survival in cancer patients.

Multi-Ingredient Preworkout Supplementation Compared With Caffeine and a Placebo Does Not Improve Repetitions to Failure in Resistance-Trained Women

There has been an increase in the use of commercially available multi-ingredient preworkout supplements (MIPS); however, there are inconsistencies regarding the efficacy of MIPS in resistance-trained women.

PURPOSE

To determine the effect of varying doses of MIPS compared with caffeine only (C) and a placebo (PL) on resistance-training performance in trained women.

METHODS

Ten women (21.5 [2.3] y) completed 1-repetition-maximum tests at baseline for leg press and bench press. A within-group, double-blind, and randomized design was used to assign supplement drinks (ie, PL, C, MIPS half scoop [MIPS-H], and MIPS full scoop [MIPS-F]). Repetitions to failure were assessed at 75% and 80% to 85% of 1-repetition maximum for bench and leg press, respectively. Total performance volume was calculated as load × sets × repetitions for each session. Data were analyzed using a 1-way repeated-measures analysis of variance and reported as means and SDs.

RESULTS

There were no differences in repetitions to failure for bench press (PL: 14.4 [3.2] repetitions, C: 14.4 [2.9] repetitions, MIPS-H: 14.2 [2.6] repetitions, MIPS-F: 15.1 [3.1] repetitions; P = .54) or leg press (PL: 13.9 [7.8] repetitions, C: 10.8 [5.9] repetitions, MIPS-H: 13.1 [7.1] repetitions, MIPS-F: 12.4 [10.7] repetitions; P = .44). Furthermore, there were no differences in total performance volume across supplements for bench press (PL: 911.2 [212.8] kg, C: 910.7 [205.5] kg, MIPS-H: 913.6 [249.3] kg, MIPS-F: 951.6 [289.6] kg; P = .39) or leg press (PL: 4318.4 [1633.6] kg, C: 3730.0 [1032.5] kg, MIPS-H: 4223.0 [1630.0] kg, MIPS-F: 4085.5 [2098.3] kg; P = .34).

CONCLUSIONS

Overall, our findings suggest that caffeine and MIPS do not provide ergogenic benefits for resistance-trained women in delaying muscular failure.

Exercise-Regulated Mitochondrial and Nuclear Signalling Networks in Skeletal Muscle

Exercise perturbs energy homeostasis in skeletal muscle and engages integrated cellular signalling networks to help meet the contraction-induced increases in skeletal muscle energy and oxygen demand. Investigating exercise-associated perturbations in skeletal muscle signalling networks has uncovered novel mechanisms by which exercise stimulates skeletal muscle mitochondrial biogenesis and promotes whole-body health and fitness. While acute exercise regulates a complex network of protein post-translational modifications (e.g. phosphorylation) in skeletal muscle, previous investigations of exercise signalling in human and rodent skeletal muscle have primarily focused on a select group of exercise-regulated protein kinases [i.e. 5' adenosine monophosphate-activated protein kinase (AMPK), protein kinase A (PKA), Ca2+/calmodulin-dependent protein kinase (CaMK) and mitogen-activated protein kinase (MAPK)] and only a small subset of their respective protein substrates. Recently, global mass spectrometry-based phosphoproteomic approaches have helped unravel the extensive complexity and interconnection of exercise signalling pathways and kinases beyond this select group and phosphorylation and/or translocation of exercise-regulated mitochondrial and nuclear protein substrates. This review provides an overview of recent advances in our understanding of the molecular events associated with acute endurance exercise-regulated signalling pathways and kinases in skeletal muscle with a focus on phosphorylation. We critically appraise recent evidence highlighting the involvement of mitochondrial and nuclear protein phosphorylation and/or translocation in skeletal muscle adaptive responses to an acute bout of endurance exercise that ultimately stimulate mitochondrial biogenesis and contribute to exercise's wider health and fitness benefits.

Polyphenol supplementation boosts aerobic endurance in athletes: systematic review

In recent years, an increasing trend has been observed in the consumption of specific polyphenols, such as flavonoids and phenolic acids, derived from green tea, berries, and other similar sources. These compounds are believed to alleviate oxidative stress and inflammation resulting from exercise, potentially enhancing athletic performance. This systematic review critically examines the role of polyphenol supplementation in improving aerobic endurance among athletes and individuals with regular exercise habits. The review involved a thorough search of major literature databases, including PubMed, Web of Science, SCOPUS, SPORTDiscus, and Embase, covering re-search up to the year 2023. Out of 491 initially identified articles, 11 met the strict inclusion criteria for this review. These studies specifically focused on the incorporation of polyphenols or polyphenol-containing complexes in their experimental design, assessing their impact on aerobic endurance. The methodology adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the risk of bias was evaluated using the Cochrane bias risk assessment tool. While this review suggests that polyphenol supplementation might enhance certain aspects of aerobic endurance and promote fat oxidation, it is important to interpret these findings with caution, considering the limited number of studies available. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023453321.

Understanding the variation in exercise responses to guide personalized physical activity prescriptions

Understanding the factors that contribute to exercise response variation is the first step in achieving the goal of developing personalized exercise prescriptions. This review discusses the key molecular and other mechanistic factors, both extrinsic and intrinsic, that influence exercise responses and health outcomes. Extrinsic characteristics include the timing and dose of exercise, circadian rhythms, sleep habits, dietary interactions, and medication use, whereas intrinsic factors such as sex, age, hormonal status, race/ethnicity, and genetics are also integral. The molecular transducers of exercise (i.e., genomic/epigenomic, proteomic/post-translational, transcriptomic, metabolic/metabolomic, and lipidomic elements) are considered with respect to variability in physiological and health outcomes. Finally, this review highlights the current challenges that impede our ability to develop effective personalized exercise prescriptions. The Molecular Transducers of Physical Activity Consortium (MoTrPAC) aims to fill significant gaps in the understanding of exercise response variability, yet further investigations are needed to address additional health outcomes across all populations.

Aerobic exercise interventions for promoting cardiovascular health and mobility after stroke: a systematic review with Bayesian network meta-analysis

OBJECTIVE

To determine the superiority of aerobic exercise (AE) interventions on key outcomes of stroke recovery, including cardiorespiratory fitness (V̇O2peak, primary outcome), systolic blood pressure (SBP) and mobility (6 min Walk Test (6MWT) distance and 10 m Usual Gait Speed) after stroke.

DATA SOURCES

MEDLINE, EMBASE, Web of Science, CINAHL, CENTRAL, SPORTDiscus, PsycINFO and AMED Allied and Complementary Medicine were searched from inception to February 2023.

ELIGIBILITY CRITERIA

Randomised controlled trials were included that compared the effects of any AE interventions (low-intensity, moderate-intensity, high-intensity continuous training (HICT), high-intensity interval training (HIIT)) to no exercise, usual care or other AE interventions in individuals poststroke.

ANALYSES

Systematic review with Bayesian network meta-analysis (NMA) methodology was employed. Surface under the cumulative ranking curve (SUCRA) values were used to rank interventions. The Grading of Recommendations, Assessment, Development and Evaluation minimally contextualised framework for NMA was followed.

RESULTS

There were 28 studies (n=1298) included in the NMA for V̇O2peak, 11 (n=648) for SBP, 28 (n=1494) for 6MWT and 18 (n=775) for the 10 m Usual Gait Speed. The greatest effect on V̇O2peak, 6MWT and 10 m Usual Gait Speed was observed after HIIT and HICT. No differences between interventions were found for SBP. SUCRA values identified HIIT as the superior AE intervention for all outcomes of interest. HIIT was the most effective intervention for improving V̇O2peak (2.9 mL/kg/min (95% credible interval 0.8 to 5.0) moderate certainty) compared with usual care.

CONCLUSION

This NMA suggests that higher-intensity AE is superior to traditional low-intensity to moderate-intensity AE for improving outcomes after stroke.

The Effect of Time-Equated Concurrent Training Programs in Resistance-Trained Men

The purpose of this investigation was to compare the effects of three different concurrent training (CT) programs and a resistance training (RT) program. Twenty-three resistance trained men (age: 24 ± 3 years) were randomized into four groups: concurrent RT and high intensity interval cycling (CTH, n = 6), concurrent RT and moderate intensity continuous cycling (CTM, n = 5), RT and barbell circuit training (RTC, n = 6), or RT only (RT, n = 6). Back squat and bench press strength, quadriceps, and pectoralis muscle thickness, VO2peak, and maximum workload (Wmax, Watts) were assessed. Squat strength gains were meaningful in all groups and comparable among CTH (16.88 kg [95% CrI: 11.15, 22.63]), CTM (25.54 kg [95% CrI: 19.24, 31.96]), RTC (17.5 kg [95% CrI: 11.66, 23.39]), and RT (20.36 kg [95% CrI: 15.29, 25.33]) groups. Bench press strength gains were meaningful in all groups and comparable among CTH (11.86 kg [95% CrI: 8.28, 15.47]), CTM (10.3 kg [95% CrI: 6.49, 14.13]), RTC (4.84 kg [95% CrI: 1.31, 8.47]), and RT (10.16 kg [95% CrI: 7.02, 13.22]) groups. Quadriceps hypertrophy was meaningful in all groups and comparable among CTH (2.29 mm [95% CrI: 0.84, 3.76]), CTM (3.41 mm [95% CrI: 1.88, 4.91]), RTC (2.6 mm [95% CrI: 1.17, 4.05]), and RT (2.83 mm [95% CrI: 1.55, 4.12]) groups. Pectoralis hypertrophy was meaningful in CTH (2.29 mm [95% CrI: -0.52, 5.1]), CTM (5.14 mm [95% CrI: 2.1, 8.15]), and RTC (7.19 mm [95% CrI: 4.26, 10.02]) groups, but not in the RT group (1 mm [95% CrI: -1.59, 3.59]); further, between-group contrasts indicated less pectoralis growth in the RT compared to the RTC group. Regarding cardiovascular outcomes, only the RTH and RTM groups experienced meaningful improvements in either measure (VO2peak or Wmax). These data suggest that the interference effect on maximal strength and hypertrophy can be avoided when the aerobic training is moderate intensity cycling, high intensity cycling, or a novel barbell circuit for ~one hour per week and on non-RT days. However, the barbell circuit failed to elicit meaningful cardiovascular adaptations.

How Does Altering the Volume-Load of Plyometric Exercises Affect the Inflammatory Response, Oxidative Stress, and Muscle Damage in Male Soccer Players?

Incorporating plyometric exercises (PE) into soccer players' conditioning routines is vital for boosting their performance. Nevertheless, the effects of PE sessions with diverse volume loads on inflammation, oxidative stress, and muscle damage are not yet clearly understood. This study aimed to examine the effects of altering the volume-loads of PE on indicators of oxidative muscle damage and inflammation. The study involved forty young male soccer players who were randomly assigned to three different volume-loads of PE (Low volume-load [100 jumps]: LVL, n = 10; Moderate volume-load [150 jumps]: MVL, n = 10; and High volume-load [200 jumps]: HVL, n = 10) and a control group (CON = 10). The levels of various biomarkers including delayed onset muscle soreness (DOMS), serum lactate dehydrogenase (LDH), creatine kinase (CK), 8-hydroxy-2-deoxyguanosine (8-OHdG), malondialdehyde (MDA), protein carbonyl (PC), leukocytes, neutrophils, interleukin-6 (IL-6), and C-reactive protein (CRP) were measured at different time points. These measurements were taken at rest, immediately after completion of PE, and 24-, 48-, and 72-hours post-PE. The CK, LDH, DOMS, 8-OHdG, MDA, and PC levels were significantly increased (p < 0.05) after the PE protocol, reaching their peak values between 24 to 48 hours post-PE for all the volume-loaded groups. The levels of leukocytes, neutrophils, and IL-6 also increased after the PE session but returned to resting values within 24 hours post-PE. On the other hand, CRP levels increased at 24 hours post-PE for all the treatment groups (p < 0.05). The changes observed in the indicators of muscle damage and inflammation in response to different volume-loads of PE was not significant. However, the HVL and MVL indicated significant differences compared to LVL in the 8-OHdG (at 48-hour) and MDA (at 72-hour). Athletes engaging in higher volume-loads demonstrated more pronounced responses in terms of biochemical variables (specifically, LVL < MVL < HVL); however, these changes were not statistically significant (except 8-OHdG and MDA).

Effectiveness of an On-Field Rehabilitation framework for return to sports in injured male professional football players: a single-blinded, prospective, randomised controlled trial

Objectives

In football, on-field rehabilitation (OFR) is critical during injury recovery for a player's safe return to sports (RTS). The study aimed to evaluate the effectiveness of an OFR framework for RTS in injured male professional football players.

Trial design

A prospective block-randomised controlled-parallel trial was conducted (level of evidence 1b).

Methods

Male professional football players (mean age, 26.3±3.6 years) from Greece diagnosed with an acute, lower limb musculoskeletal (MSK) injury (confirmed clinically and through imaging) participated in the study. During rehabilitation, the participants' OFR was guided by either the On-Field Rehabilitation (On FI.RE.) accelerated framework (experimental group) or a traditional OFR framework for a late injury recovery phase (comparison group). Between July 2021 and January 2022, 76 players were randomly allocated to the experimental group (n=38) and the comparison group (n=38). Participants were blinded during the study regarding intervention therapeutic protocols. The primary outcome measure was the effect of On FI.RE. framework on the time needed to return to team training (RTT) participation. The correlation between the time needed to return to on-field activity and RTT was calculated. Subsequent injuries were registered for a 12-month follow-up period.

Results

The intervention protocol, On FI.RE. framework, had a statistically significant effect on the time needed to RTT (F(1) = 49 626, p<0.001) with a large effect size (ES; η2=0.422) and fewer days (mean=23.8±9.1 days) needed than the comparison group (mean=30.3±9.8 days). There was a strong correlation between return to on-field activity and the time needed to RTT (r(76) = 0.901, p<0001) with a large ES (r>0.5). Six subsequent injuries were registered in the traditional OFR framework group, and one subsequent injury in the On FI.RE. framework group after a follow-up period of 12 months.

Conclusion

The On FI.RE., an accelerated OFR framework during injury recovery, is more effective than a traditional OFR framework, reducing the time a player needs to RTS. It entails a very low risk of reinjury.

Trial registration number

NCT05163470.

Comparative efficacy of concurrent training types on lower limb strength and muscular hypertrophy: A systematic review and network meta-analysis

Objective

This study aims to compare, through quantitative analysis, the effectiveness of different endurance training types on increasing lower limb strength and muscle cross-sectional area (MCSA) in concurrent training.

Methods

This systematic literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) [PROSPERO ID: CRD42023396886]. Web of Science, SportDiscuss, Pubmed, Cochrane, and Scopus were systematically searched from their inception date to October 20, 2023.

Results

A total of 40 studies (841 participants) were included in this meta-analysis. MCSA analysis showed that, compared to resistance training alone, concurrent high-intensity interval running training and resistance training and concurrent moderate-intensity continuous cycling training and resistance training were more effective (SMD = 0.15, 95% CI = -0.46 to 0.76, and SMD = 0.07, 95% CI = -0.24 to 0.38 respectively), while other modalities of concurrent training not. Lower body maximal strength analysis showed that all modalities of concurrent training were inferior to resistance training alone, but concurrent high-intensity interval training and resistance training showed an advantage in four different concurrent training modalities (SMD = -0.08, 95% CI = -0.25 to 0.08). For explosive strength, only concurrent high-intensity interval training and resistance training was superior to resistance training (SMD = 0.06, 95% CI = -0.21 to 0.33).

Conclusion

Different endurance training types have an impact on the effectiveness of concurrent training, particularly on lower limb strength. Adopting high-intensity interval running as the endurance training type in concurrent training can effectively minimize the adverse effects on lower limb strength and MCSA.

Resistance-only and concurrent exercise induce similar myofibrillar protein synthesis rates and associated molecular responses in moderately active men before and after training

Aerobic and resistance exercise (RE) induce distinct molecular responses. One hypothesis is that these responses are antagonistic and unfavorable for the anabolic response to RE when concurrent exercise is performed. This thesis may also depend on the participants' training status and concurrent exercise order. We measured free-living myofibrillar protein synthesis (MyoPS) rates and associated molecular responses to resistance-only and concurrent exercise (with different exercise orders), before and after training. Moderately active men completed one of three exercise interventions (matched for age, baseline strength, body composition, and aerobic capacity): resistance-only exercise (RE, n = 8), RE plus high-intensity interval exercise (RE+HIIE, n = 8), or HIIE+RE (n = 9). Participants trained 3 days/week for 10 weeks; concurrent sessions were separated by 3 h. On the first day of Weeks 1 and 10, muscle was sampled immediately before and after, and 3 h after each exercise mode and analyzed for molecular markers of MyoPS and muscle glycogen. Additional muscle, sampled pre- and post-training, was used to determine MyoPS using orally administered deuterium oxide (D2 O). In both weeks, MyoPS rates were comparable between groups. Post-exercise changes in proteins reflective of protein synthesis were also similar between groups, though MuRF1 and MAFbx mRNA exhibited some exercise order-dependent responses. In Week 10, exercise-induced changes in MyoPS and some genes (PGC-1ɑ and MuRF1) were dampened from Week 1. Concurrent exercise (in either order) did not compromise the anabolic response to resistance-only exercise, before or after training. MyoPS rates and some molecular responses to exercise are diminished after training.

Regulatory T cells shield muscle mitochondria from interferon-γ-mediated damage to promote the beneficial effects of exercise

Exercise enhances physical performance and reduces the risk of many disorders such as cardiovascular disease, type 2 diabetes, dementia, and cancer. Exercise characteristically incites an inflammatory response, notably in skeletal muscles. Although some effector mechanisms have been identified, regulatory elements activated in response to exercise remain obscure. Here, we have addressed the roles of Foxp3+CD4+ regulatory T cells (Tregs) in the healthful activities of exercise via immunologic, transcriptomic, histologic, metabolic, and biochemical analyses of acute and chronic exercise models in mice. Exercise rapidly induced expansion of the muscle Treg compartment, thereby guarding against overexuberant production of interferon-γ and consequent metabolic disruptions, particularly mitochondrial aberrancies. The performance-enhancing effects of exercise training were dampened in the absence of Tregs. Thus, exercise is a natural Treg booster with therapeutic potential in disease and aging contexts.

Physiology of Stretch-Mediated Hypertrophy and Strength Increases: A Narrative Review

Increasing muscle strength and cross-sectional area is of crucial importance to improve or maintain physical function in musculoskeletal rehabilitation and sports performance. Decreases in muscular performance are experienced in phases of reduced physical activity or immobilization. These decrements highlight the need for alternative, easily accessible training regimens for a sedentary population to improve rehabilitation and injury prevention routines. Commonly, muscle hypertrophy and strength increases are associated with resistance training, typically performed in a training facility. Mechanical tension, which is usually induced with resistance machines and devices, is known to be an important factor that stimulates the underlying signaling pathways to enhance protein synthesis. Findings from animal studies suggest an alternative means to induce mechanical tension to enhance protein synthesis, and therefore muscle hypertrophy by inducing high-volume stretching. Thus, this narrative review discusses mechanical tension-induced physiological adaptations and their impact on muscle hypertrophy and strength gains. Furthermore, research addressing stretch-induced hypertrophy is critically analyzed. Derived from animal research, the stretching literature exploring the impact of static stretching on morphological and functional adaptations was reviewed and critically discussed. No studies have investigated the underlying physiological mechanisms in humans yet, and thus the underlying mechanisms remain speculative and must be discussed in the light of animal research. However, studies that reported functional and morphological increases in humans commonly used stretching durations of > 30 min per session of the plantar flexors, indicating the importance of high stretching volume, if the aim is to increase muscle mass and maximum strength. Therefore, the practical applicability seems limited to settings without access to resistance training (e.g., in an immobilized state at the start of rehabilitation), as resistance training seems to be more time efficient. Nevertheless, further research is needed to generate evidence in different human populations (athletes, sedentary individuals, and rehabilitation patients) and to quantify stretching intensity.

Empagliflozin induces the transcriptional program for nutrient homeostasis in skeletal muscle in normal mice

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve heart failure (HF) outcomes across a range of patient characteristics. A hypothesis that SGLT2i induce metabolic change similar to fasting has recently been proposed to explain their profound clinical benefits. However, it remains unclear whether SGLT2i primarily induce this change in physiological settings. Here, we demonstrate that empagliflozin administration under ad libitum feeding did not cause weight loss but did increase transcripts of the key nutrient sensors, AMP-activated protein kinase and nicotinamide phosphoribosyltransferase, and the master regulator of mitochondrial gene expression, PGC-1α, in quadriceps muscle in healthy mice. Expression of these genes correlated with that of PPARα and PPARδ target genes related to mitochondrial metabolism and oxidative stress response, and also correlated with serum ketone body β-hydroxybutyrate. These results were not observed in the heart. Collectively, this study revealed that empagliflozin activates transcriptional programs critical for sensing and adaptation to nutrient availability intrinsic to skeletal muscle rather than the heart even in normocaloric condition. As activation of PGC-1α is sufficient for metabolic switch from fatigable, glycolytic metabolism toward fatigue-resistant, oxidative mechanism in skeletal muscle myofibers, our findings may partly explain the improvement of exercise tolerance in patients with HF receiving empagliflozin.

Applied high-intensity interval cardio yoga improves cardiometabolic fitness, energetic contributions, and metabolic flexibility in healthy adults

Purpose: Currently, there is no interventional approach to increase the intensity of Surya Namaskar a popular hatha yoga sequence used worldwide. Therefore, this study investigated how tempo-based high-intensity interval cardio yoga (HIICY) and traditional interval hatha yoga (TIHY) affects cardiometabolic fitness in active adults. Methods: Twenty physically active male and female individuals were randomly separated into HIICY (5 males, 5 females, 1.5 s tempo) and TIHY (5 males, 5 females, 3 s tempo) groups. The intervention included twelve exercise sessions for 4 weeks in both groups. Participants conducted a ramp test to determine their maximal oxygen uptake (V ˙ O2max), maximal velocity at V ˙ O2max (vV ˙ O2max), and maximal heart rate (HRmax). Afterward, they performed a 10-min high-intensity cardio yoga test (HICYT) to determine heart rate (HRpeak and HRmean), oxygen uptake (V ˙ O2peak and V ˙ O2mean), respiratory exchange ratio (RER), blood lactate concentrations (La- peak and ∆La-), fat and carbohydrate oxidations (FATox, CHOox), and energetic contributions (oxidative; W Oxi, glycolytic; W Gly, and phosphagen; W PCr, total energy demand; W Total). Results: V ˙ O2max and vV ˙ O2max showed time and group × time interactions (p < 0.01, p < 0.0001, p < 0.001, respectively). V ˙ O2max after HIICY was significantly higher than in pre-testing and following TIHY (p < 0.001, p < 0.0001, respectively). V ˙ O2peak, V ˙ O2mean, RER, HRpeak, and HRmean during the 10-min HICYT showed significant time effects (p < 0.05). ∆La- indicated a group × time interaction (p < 0.05). Group x time interaction effects for FATox at the fourth and sixth minute were observed (p < 0.05, respectively). Absolute (kJ) and relative (%) W Oxi, W Gly, and W Total showed time and group × time interaction effects (p < 0.05, p < 0.01, respectively). Furthermore, %W Gly was reduced following HIICY (p < 0.05). Additionally, V ˙ O2max and vV ˙ O2max were highly correlated with W Oxi in kJ (r = 0.91, 0.80, respectively). Moderate to high correlations were observed among CHOox, FATox, and absolute V ˙ O2max (r = 0.76, 0.62, respectively). Conclusion: A 4-week period of HIICY improved cardiometabolic fitness, oxidative capacity, and metabolic flexibility compared with TIHY, in physically active adults. Therefore, HIICY is suitable as HY-specific HIIT and time-efficient approach for relatively healthy individuals.

Effects of Treadmill Running at Different Light Cycles in Mice with Metabolic Disorders

Type 2 diabetes mellitus accounts for about 90% of cases of diabetes and is considered one of the most important problems of our time. Despite a significant number of studies on glucose metabolism, the molecular mechanisms of its regulation in health and disease remain insufficiently studied. That is why non-drug treatment of metabolic disorders is of great relevance, including physical activity. Metabolic changes under the influence of physical activity are very complex and are still difficult to understand. This study aims to deepen the understanding of the effect of physical exercise on metabolic changes in mice with diabetes mellitus. We studied the effect of forced treadmill running on body weight and metabolic parameters in mice with metabolic disorders. We developed a high-fat-diet-induced diabetic model of metabolic disorders. We exposed mice to forced treadmill running for 4 weeks. We determined glucose and insulin levels in the blood plasma biochemically and analyzed Glut-4 and citrate synthase in M. gastrocnemius muscle tissue using Western blotting. The research results show that daily treadmill running has different effects on different age groups of mice with metabolic disorders. In young-age animals, forced running has a more pronounced effect on body weight. At week 12, young obese mice had a 17% decrease in body weight. Body weight did not change in old mice. Moreover, at weeks 14 and 16, the decrease in body weight was more significant in the young mice (by 17%) compared to the old mice (by 6%) (p < 0.05). In older animals, it influences the rate of glucose uptake. At 60 min, the blood glucose in the exercised older mice decreased to 14.46 mmol/L, while the glucose concentration in the non-exercised group remained at 17 mmol/L. By 120 min, in mice subjected to exercise, the blood glucose approached the initial value (6.92 mmol/L) and amounted to 8.35 mmol/L. In the non-exercised group, this difference was 45%. The effects of physical activity depend on the time of day. The greater effect is observed when performing shift training or exercise during the time when animals are passive (light phase). In young mice, light phase training had a significant effect on increasing the content of Glut-4 in muscle tissue (84.3 ± 11.3%, p < 0.05 with control group-59.3 ± 7.8%). In aged mice, shift training caused an increase in the level of Glut-4 in muscle tissue (71.3 ± 4.1%, p < 0.05 with control group-56.4 ± 10,9%). In the group of aged mice, a lower CS level was noticed in all groups in comparison with young mice. It should also be noted that we observed that CS increased during exercise in the group of young mice, especially during light phase training. The CS content in the light phase subgroup (135.8 ± 7.0%) was higher than in the dark phase subgroup (113.3 ± 7.7%) (p = 0.0006). The CS decreased in aged chow-fed mice and increased in the high-fat-fed group. The CS content in the chow diet group (58.2 ± 5.0%) was 38% lower than in the HFD group (94.9 ± 8.8%).

Running with whole-body electromyostimulation improves physiological determinants of endurance performance - a randomized control trial

BACKGROUND

This study aimed to evaluate the physiological and metabolic adaptations to an eight-week running intervention with whole-body electromyostimulation (wbEMS) compared to running without wbEMS.

METHODS

In a randomized controlled trial (RCT), 59 healthy participants (32 female/ 27 male, 41 ± 7 years, rel.V̇O2max 40.2 ± 7.4 ml/min/kg) ran twice weekly à 20 min for eight weeks either with a wbEMS suit (EG) or without wbEMS (control group, CG). Before and after the intervention, (i) rel.V̇O2max, heart rate and time to exhaustion were recorded with an incremental step test with an incremental rate of 1.20 km/h every 3 min. They were interpreted at aerobic and (indirect) anaerobic lactate thresholds as well as at maximum performance. (ii) Resting metabolic rate (RQ) as well as (iii) body composition (%fat) were assessed.

RESULTS

Following the intervention, V̇O2max was significantly enhanced for both groups (EG ∆13 ± 3%, CG ∆9 ± 3%). Velocity was elevated at lactate thresholds and maximum running speed (EG ∆3 ± 1%, CG ∆2 ± 1%); HRmax was slightly reduced by -1 beat/min. No significant changes were observed for time until exhaustion and lactate. RQ was significantly enhanced following both trainings by + 7%. %fat was reduced for both groups (EG ∆-11 ± 3%, CG ∆-16 ± 5%), without any changes in body mass. Results did not differ significantly between groups.

CONCLUSIONS

Both interventions had a positive impact on aerobic power. The rightward shift of the time-velocity graph points towards improved endurance performance. The effects of wbEMS are comparable to those after high-intensity training and might offer a time-efficient alternative to affect physiological and metabolic effects.

TRIAL REGISTRATION

German Clinical Trials Register, ID DRKS00026827, date 10/26/21.

The acute and repeated bout effects of multi-joint eccentric exercise on physical function and balance in older adults

PURPOSE

Eccentric muscle actions generate high levels of force at a low metabolic cost, making them a suitable training modality to combat age-related neuromuscular decline. The temporary muscle soreness associated with high intensity eccentric contractions may explain their limited use in clinical exercise prescription, however any discomfort is often alleviated after the initial bout (repeated bout effect). Therefore, the aims of the present study were to examine the acute and repeated bout effects of eccentric contractions on neuromuscular factors associated with the risk of falling in older adults.

METHODS

Balance, functional ability [timed up-and-go and sit-to-stand], and lower-limb maximal and explosive strength were measured in 13 participants (67.6 ± 4.9 year) pre- and post-eccentric exercise (0, 24, 48, and 72 hr) in Bout 1 and 14 days later in Bout 2. The eccentric exercise intervention was performed on an isokinetic unilateral stepper ergometer at 50% of maximal eccentric strength at 18 step‧min-1 per limb for 7 min (126 steps per limb). Two-way repeated measures ANOVAs were conducted to identify any significant effects (P ≤ 0.05).

RESULTS

Eccentric strength significantly decreased (- 13%) in Bout 1 at 24 hr post-exercise; no significant reduction was observed at any other time-point after Bout 1. No significant reductions occurred in static balance or functional ability at any time-point in either bout.

CONCLUSION

Submaximal multi-joint eccentric exercise results in minimal disruption to neuromuscular function associated with falls in older adults after the initial bout.

Beneficial Effects of Asparagus officinalis Extract Supplementation on Muscle Mass and Strength following Resistance Training and Detraining in Healthy Males

The phytoecdysteroid 20-hydroxyecdysone (20E) is widely used for resistance training (RT). Little is known about its potential ergogenic value and detraining effects post-RT. This study aimed to examine the effects of 20E extracted from Asparagus officinalis (A. officinalis) on muscle strength and mass, as well as anabolic and catabolic hormones following RT and detraining. Twenty males, aged 20.1 ± 1.1 years, were matched and randomly assigned to consume double-blind supplements containing either a placebo (PLA) or 30 mg/day of 20E for 12 weeks of RT and detraining. Before and after RT and detraining, muscle strength and mass and anabolic and catabolic hormones were measured. This study found that 20E reduced cortisol levels significantly (p < 0.05) compared to the PLA, yet no effect was observed on muscle mass, strength, or anabolic hormones after RT. Subsequent to 6 weeks of detraining, the 20E demonstrated a lower percentage change in 1RM bench press/FFM than the PLA (p < 0.05). Compared to the PLA, detraining throughout the 12 weeks resulted in a lower percentage change in thigh (p < 0.05) and chest (p < 0.01) circumferences, as well as reduced cortisol levels (p < 0.01), with 20E. Our findings demonstrate that 20E supplementation is a promising way to maintain muscle mass and strength during detraining. Accordingly, 20E may prevent muscle mass and strength loss due to detraining by lowering catabolic hormone levels.

The Emerging Role of Hypoxic Training for the Equine Athlete

This paper provides a comprehensive discussion on the physiological impacts of hypoxic training, its benefits to endurance performance, and a rationale for utilizing it to improve performance in the equine athlete. All exercise-induced training adaptations are governed by genetics. Exercise prescriptions can be tailored to elicit the desired physiological adaptations. Although the application of hypoxic stimuli on its own is not ideal to promote favorable molecular responses, exercise training under hypoxic conditions provides an optimal environment for maximizing physiological adaptations to enhance endurance performance. The combination of exercise training and hypoxia increases the activity of the hypoxia-inducible factor (HIF) pathway compared to training under normoxic conditions. Hypoxia-inducible factor-1 alpha (HIF-1α) is known as a master regulator of the expression of genes since over 100 genes are responsive to HIF-1α. For instance, HIF-1-inducible genes include those critical to erythropoiesis, angiogenesis, glucose metabolism, mitochondrial biogenesis, and glucose transport, all of which are intergral in physiological adaptations for endurance performance. Further, hypoxic training could conceivably have a role in equine rehabilitation when high-impact training is contraindicated but a quality training stimulus is desired. This is achievable through purpose-built equine motorized treadmills inside commercial hypoxic chambers.