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The decision of the Union Internationale de Pentathlon Moderne to replace horse riding with Obstacle after the 2024 Olympic Games challenges training, testing, and recovery management in Modern Pentathlon. This commentary discusses physiological, technical, and tactical effects of rule changes in the 5 disciplines with a specific focus on the new discipline Obstacle. Modern Pentathlon requires athletes to develop specific endurance capacities relying on both the aerobic and anaerobic systems while simultaneously increasing lower- and upper-body strength capabilities. In addition, movements must be repeatedly executed in an explosive and precise manner. Running and swimming must be fast but economical. Swapping from horse riding to Obstacle will prioritize the explosive strength of the upper extremities and core while keeping high levels of endurance and precision in swimming, fencing, and shooting. Moreover, condensing the Modern Pentathlon competition to a 90-minute television-friendly format enables more competitions in the future. Athletes and coaches will thus also need to develop and maintain effective individual peri-exercise routines (before, during, and after the competition) to successfully meet the resulting tactical and physical challenges of the new format. This commentary aims to stimulate the discussion on the effect of the Union Internationale de Pentathlon Moderne's decisions to replace riding with the new Obstacle discipline and implement a more television-friendly format with a focus on physiological, technical, and tactical aspects. [ABSTRACT FROM AUTHOR]

Purpose: To study whether, during typical-level running, non-rear-foot strikers (non-RFS) or rear-foot strikers (RFS) presented a similar or different extent of neuromuscular fatigue after a prolonged graded run. Methods: Sixteen experienced male trail runners (8 non-RFS and 8 RFS) performed a 2.5-hour treadmill graded running exercise. Before and after exercise, neuromuscular tests were performed to assess neuromuscular fatigue of the plantar flexors. Biomechanical gait parameters were acquired with an instrumented treadmill, and electromyographic activity of the lower-limb muscles was collected as an index of muscle activation. Results: There were no significant time × foot strike interactions for neuromuscular (all P ≥.742), muscle activation (all P ≥.157), or biomechanical (all P ≥.096) variables. Conclusions: A dominant level running foot-strike pattern did not directly affect the extent of neuromuscular fatigue during a prolonged graded run. This suggests that no ideal running foot-strike pattern exists to minimize neuromuscular fatigue during prolonged-duration races wherein cumulative uphill and downhill segments are high, such as in trail running. [ABSTRACT FROM AUTHOR]

Purpose: Antarctic expeditions are exceptional physiological challenges. Sleep plays a critical role in athletic performance, recovery, and wellness, with sleep disturbances having a negative impact on health and performance. Methods: The authors investigated sleep, fatigue, and recovery profiles of the longest solo unsupported one-way polar ski journey across Antarctica. A 33-year-old woman covered 1484.53 km from Hercules Inlet to the South Pole, finishing at the Ross Ice Shelf, in 70 days and 16 hours. Questionnaires on sleep (Pittsburgh Insomnia Rating Scale and Karolinska Sleepiness Scale), fatigue (Subjective Assessment of Fatigue), recovery (Total Quality Recovery), and wellness were completed at different time points (before, during, and after the expedition). Results: Average daily sleep time was between 4 and 5 hours, increasing to 7 hours for the final part of the expedition. Satisfaction of sleep and lack of energy deteriorated as the expedition progressed, alongside signs of clinical insomnia. Fatigue and muscle soreness increased with increasing milage, with extreme levels and very poor recovery toward the end of the expedition. Despite this, the adventurer continued to perform on extremely high levels. Postexpedition scores returned to baseline, demonstrating the incredible adaptation and ability to recovery. The postexpedition interview showed that prior experience of an Antarctic expedition may have prepared the athlete and made her more resilient for this challenge. Conclusions: The data provide unique insights into Antarctic expeditions and may help us understand the limits of human performance when planning future expeditions of this nature. Female athletes are capable of extreme challenges, breaking established performance boundaries. [ABSTRACT FROM AUTHOR]

Understanding the changes in running mechanics caused by fatigue is essential to assess its impact on athletic performance. Changes in running biomechanics after constant speed conditions are well documented, but the adaptive responses after a maximal incremental test are unknown. We compared the spatiotemporal, joint kinematics, elastic mechanism, and external work parameters before and after a maximal incremental treadmill test. Eighteen recreational runners performed 2-minute runs at 8 km·h−1 before and after a maximal incremental test on a treadmill. Kinematics, elastic parameters, and external work were determined using the OpenCap and OpenSim software. We did not find differences in spatiotemporal parameters and elastic parameters (mechanical work, ankle, and knee motion range) between premaximal and postmaximal test conditions. After the maximal test, the runners flexed their hips more at contact time (19.4°–20.6°, P =.013) and presented a larger range of pelvis rotation at the frontal plane (10.3°–11.4°, P =.002). The fatigue applied in the test directly affects pelvic movements; however, it does not change the lower limb motion or the spatiotemporal and mechanical work parameters in recreational runners. A larger frontal plane motion of the pelvis deserves attention due to biomechanical risk factors associated with injuries. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of knee joint range of motion (RoM) on the torque–velocity relationship and fatigue in the knee extensor muscles of 7 young (median = 26 y) and 7 older (68 y) adults. Each leg was assigned a RoM (35° or 75°) over which to perform a torque–velocity protocol (maximal isokinetic contractions, 60–300°·s−1) and a fatigue protocol (120 maximal contractions at 120°·s−1, 0.5 Hz). Six older participants were unable to reach 300°·s−1 over 35°. Therefore, the velocity eliciting 75% of peak torque at 60°·s−1 (V75, °·s−1) was calculated for each RoM from a fit of individual torque–velocity curves (60–240°·s−1), and ΔV75 (35°–75°) was determined. Fatigue (final torque/initial torque) was used to calculate Δfatigue (35°–75°). ΔV75 was not different from 0 in young (−28.3°·s−1 [−158.6 to 55.7], median [range], P =.091) or older (−18.5°·s−1 [−95.0 to 23.9], P =.128), with no difference by age (P =.710). In contrast, fatigue was greater for 75° in young (Δfatigue = 25.9% [17.5–30.3], P =.018) and older (17.2% [11.9–52.9], P =.018), with no effect of age (P =.710). These data indicate that, regardless of age, RoM did not alter the torque–velocity relationship between 60 and 240°·s−1, and fatigue was greater with a larger RoM. [ABSTRACT FROM AUTHOR]

Purpose: To investigate how cycling time-trial (TT) performance changes over a cycling season, both in a "fresh" state and in a "fatigued" state (durability). Additionally, the aim was to explore whether these changes are related to changes in underlying physiological factors such as gross efficiency, energy expenditure (EE), and substrate oxidation (fat oxidation [FatOx] and carbohydrate oxidation [CarbOx]). Methods: Sixteen male semiprofessional cyclists visited the laboratory on 3 occasions during a cycling season (PRE, START, and IN) and underwent a performance test in both fresh and fatigued states (after 38.1 [4.9] kJ/kg), containing a submaximal warm-up for the measurement of gross efficiency, EE, FatOx, and CarbOx and a maximal TT of 1 (TT1min) and 10 minutes (TT10min). Results were compared across states (fresh vs fatigued) and periods (PRE, START, and IN). Results: The average power output (PO) in TT1min decreased (P <.05) from fresh to fatigued state across all observed periods, whereas there was no change in the PO in TT10min. Over the course of the season, the PO in TT1min in the fatigued state improved more compared with the PO in TT1min in the fresh state. Furthermore, while EE did not significantly change, there was an increase in FatOx and a decrease in CarbOx toward the fatigued state. These changes diminished during the cycling season (IN), indicating a greater contribution of CarbOx in the fatigued state. Conclusions: TT1min performance is more sensitive to fatigue compared with TT10min. Also, during a cycling season, durability improves more when compared with fresh maximal POs, which is also observed in the changes in substrate oxidation. [ABSTRACT FROM AUTHOR]

Purpose: This cohort study aimed to investigate the relationship between subjective (wellness and internal training load [ITL]) and objective (neuromuscular fatigue) monitoring markers and performance aspects (reception quality [RQ] and attack efficiency [AE]) in professional female volleyball players. Methods: The study was conducted over an 8-week period during the final mesocycle of the competitive phase. A total of 24 training sessions and 10 matches were included in the analysis. Subjective measures of wellness and ITL were assessed, and neuromuscular fatigue was evaluated using countermovement-jump (CMJ) height. RQ and AE were determined based on game statistics. Results: The study found a positive relationship between wellness and RQ, particularly affecting outside hitters and liberos. ITL showed a positive association with AE, primarily impacting outside hitters, opposite hitters, and middle blockers. Additionally, ITL demonstrated a negative correlation with RQ, mainly affecting outside hitters and liberos. CMJ performance was associated with AE, where a decrease in CMJ height was linked to reduced AE. Conclusions: The findings highlight the importance of considering players' wellness scores in training and match strategies for different positions. Careful management of training loads, considering both physical and technical demands, is crucial for optimizing performance outcomes. Monitoring neuromuscular fatigue, as indicated by CMJ performance, is particularly relevant for outside hitters, opposite hitters, and middle blockers involved in attack actions. Coaches, trainers, and sports practitioners can use these insights to develop position-specific training protocols and implement effective strategies for maintaining or improving performance metrics under various stressors. [ABSTRACT FROM AUTHOR]

Nitrate ( NO 3 − ) has properties that can improve muscle function, leading to improvements in metabolic cost of exercise as well as enhance force production. Gymnastics is a whole-body sport, involving events that demand a high level of strength and fatigue resistance. However, the effect of NO 3 − supplementation on both upper- and lower-body function in gymnasts is unknown. This study examined the effect of acute beetroot juice (BRJ) supplementation on isokinetic strength and endurance of the upper- and lower-body in highly trained international-level male gymnasts. In a double-blind, randomized crossover design, 10 international-level male gymnasts completed two acute supplementation periods, consuming either 2 × 70 ml NO 3 − -rich (∼12.8 mmol/L of NO 3 − ) or NO 3 − -depleted (PLA) BRJ. Maximal strength of the upper-leg and upper-arm at 60°/s, 120°/s, 180°/s, and 300°/s, and muscular endurance (50 repeated isokinetic contractions at 180°/s) were assessed. Plasma NO 3 − (BRJ: 663 ± 164 μM, PLA: 89 ± 48 μM) and nitrite ( NO 2 − ) concentrations (BRJ: 410 ± 137 nmol/L, PLA: 125 ± 36 nmol/L) were elevated following BRJ compared to PLA (both p <.001). Maximal strength of knee and elbow extensors and flexors did not differ between supplements (p >.05 for all velocities). Similarly, fatigue index of knee and elbow extension and flexion was not different between supplements (all p >.05). Acute BRJ supplementation, containing ∼12.8 mmol/L of NO 3 − , increased plasma NO 3 − and NO 2 − concentrations, but did not enhance isokinetic strength or fatigue resistance of either upper or lower extremities in international-level male gymnasts. [ABSTRACT FROM AUTHOR]

Context: Blood flow restriction (BFR) is a rehabilitation tool which may introduce a constraint, similar to muscle fatigue, that challenge patients' sensorimotor system during balance exercises. The purpose of our study was to examine whether adding BFR to dynamic balance exercises produced a decrease in balance performance and an increase in ratings of perceived exertion and instability in individuals with chronic ankle instability (CAI) compared with dynamic balance exercises without BFR. Designs: Crossover design. Methods: Our sample included N = 25 young adults with a history of CAI. Participants completed 2 laboratory visits. At each visit, participants completed 4 sets (30×-15×-15×-15×) of dynamic balance exercises, performed similar to the modified star excursion balance test (SEBT), once with BFR and once with control (no BFR) conditions. We measured composite SEBT scores at baseline and during the final repetitions of each set of balance exercise (sets 1–4). We also measured ratings of perceived exertion and instability following each balance exercise set. Results: We observed no difference in composite SEBT scores between conditions at baseline; however, composite SEBT scores were significantly lower during all balance exercises sets 1 to 4 with the BFR condition compared with control. During the BFR condition, composite SEBT scores were significantly lower during all balance exercise sets compared with baseline. During the control condition, composite SEBT scores did not significantly change between baseline and each balance exercise set. Ratings of perceived exertion and instability scores were significantly greater in the BFR group compared with the control group during all balance exercise sets. Conclusions: Individuals with CAI demonstrated lower composite SEBT scores and greater perceived instability and exertion during dynamic balance exercise with BFR compared to without BFR. BFR introduced a novel muscle fatigue constraint during dynamic balance exercises in individuals with CAI. Additional research is needed to determine if adding BFR to balance training could improve clinical outcomes in CAI patients. [ABSTRACT FROM AUTHOR]

Introduction: This case study aimed to describe potential changes in neuromuscular activation and synergies after an 8-day cross-country mountain-bike stage race. Methods: A peak power output test was performed 5 days before the race. Two days before the start and after 7 days of racing, the athlete performed a power-based Lamberts Submaximal Cycling Test, including surface electromyography, and completed a Daily Analysis of Life Demands of Athletes questionnaire. Neuromuscular activation, in terms of root mean square, timing (onset-offset) of muscle activation, and synergies, was obtained from electromyography recordings. Results: The athlete reported an increase in symptoms of experienced stress after the stage race on the Daily Analysis of Life Demands of Athletes questionnaire. Both biceps femoris and tibialis anterior muscles showed a reduction in normalized amplitude after the stage race. In addition, the number of synergies that was necessary to describe neuromuscular activation increased from 2 to 3. Conclusions: In this case study, the increase in synergies suggests that, after the stage race, the athlete showed a more complex muscle-recruitment pattern. This may indicate that muscle coordination can change when muscle fatigue occurs; however, further research is needed to confirm these results in a larger sample. [ABSTRACT FROM AUTHOR]

Purpose: Fran is one of the most popular CrossFit benchmark workouts used to control CrossFitters' improvements. Detailed physiological characterization of Fran is needed for a more specific evaluation of CrossFitters' training performance improvements. The aim of the study was to analyze the oxygen uptake ( V ˙ O 2 ) kinetics and characterize the energy system contributions and the degree of postexercise fatigue of the unbroken Fran. Methods: Twenty trained CrossFitters performed Fran at maximal exertion. V ˙ O 2 and heart-rate kinetics were assessed at baseline and during and post-Fran. Blood lactate and glucose concentrations and muscular fatigue were measured at baseline and in the recovery period. Results: A marked increase in V ˙ O 2 kinetics was observed at the beginning of Fran, remaining elevated until the end (V ˙ O 2 peak : 49.2 [3.7] mL·kg−1·min−1, V ˙ O 2 amplitude: 35.8 [5.2] mL·kg−1·min−1, time delay: 4.7 [2.5] s and time constant: 23.7 [11.1] s; mean [SD]). Aerobic, anaerobic lactic, and alactic pathways accounted for 62% (4%), 26% (4%), and 12% (2%) of energy contribution. Reduction in muscle function in jumping ability (jump height: 8% [6%], peak force: 6% [4%], and maximum velocity: 4% [2%]) and plank prone test (46% [20%]) was observed in the recovery period. Conclusions: The Fran unbroken workout is a high-intensity effort associated with an elevated metabolic response. This pattern of energy response highlights the primary contribution of aerobic energy metabolism, even during short and very intense CrossFit workouts, and that recovery can take >24 hours due to cumulative fatigue. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the interference effects of various resistance-training (RT) protocols on rowing ergometer performance. Methods: Fourteen semiprofessional male rowers randomly completed 5 protocols in separate sessions: (1) control—no RT session was performed, (2) upper-body high-fatigue—4 sets to failure during the bench pull exercise, (3) upper-body low-fatigue—4 sets of 6 repetitions during the bench pull exercise, (4) lower-body high-fatigue—4 sets to failure during the leg-press exercise, and (5) lower-body low-fatigue—4 sets of 6 repetitions during the leg-press exercise. All sets were performed against the 12-repetition-maximum load with 2 minutes of interset rest. Following the completion of the protocols, subjects performed an all-out 1000-m rowing ergometer test. Results: Compared with the control condition, rowing ergometer performance was not significantly affected after the low-fatigue RT protocols (upper body: P ≥.487; Δ = 0.0%–0.2%; lower body: P ≥.200; Δ = −0.2%–0.5%), while it significantly declined following high-fatigue RT protocols (upper body: P ≤.001; Δ = 1.0%–2.0%; lower body: P ≤.002; Δ = 2.1%–2.5%). The average heart rate was significantly lower for the control condition compared with all RT protocols (P ≤.043; Δ = 1.0%–1.5%). Conclusions: To minimize interference on rowing performance, coaches should prioritize the level of effort in RT protocols over specific exercises, specifically avoiding high-fatigue protocols that lead to failure before rowing practice. [ABSTRACT FROM AUTHOR]

This study investigated: 1) monitoring post-match neuromuscular fatigue (NMF) status in rugby union players using two submaximal running tests (SRT); and 2) the sensitivity of each SRT to locomotor variables obtained during match-play. Twenty-three male rugby players (age: 21.0 ± 1.3 years; height: 185.2 ± 6.1 cm; body mass; 97.3 ± 10.3 kg) were monitored across one season (n = 71 player-match and 159 fatigue-players-testing observations). Two different SRTs (SRT-jog [5-minute shuttle run protocol] and SRT-stride [a repeat stride effort protocol]) were used to characterise post-match NMF, with measures taken two days prior to match day (baseline), on MD + 1, and MD + 2. Linear mixed models (±90% CIs) were used to explore differences between measures and match-play locomotor variables. SRT-jog presented a meaningful increase following MD + 1 (ES: 0.63 [0.37 to 0.89]). SRT-Stride showed small increases at MD + 1 (ES: 0.24 [0.02 to 0.49]) and MD + 2 (ES: 0.33 [0.07 to 0.59]) suggesting a potential impairment in running mechanics. SRT-stride was significantly associated with total distance (ES: 0.41 [−0.01 to 0.83]) and collisions (ES: 0.58 [0.18 to 0.99]). While both tests presented small to moderate changes post-match, only the SRT-stride was related to match locomotor variables. Therefore, the SRT-stride may be a more sensitive monitoring tool for monitoring NMF in rugby union players. [ABSTRACT FROM AUTHOR]

Key points The cellular causes of the age‐related loss in power output and increased fatigability are unresolved. We previously observed that the depressive effects of hydrogen (H+) (pH 6.2) and inorganic phosphate (Pi) (30 mm) did not differ in muscle fibres from young and older men. However, the effects may have been saturated in the severe fatigue‐mimicking condition, potentially masking age differences in the sensitivity of the cross‐bridge to these metabolites. Thus, we compared the contractile mechanics of muscle fibres from the vastus lateralis of 13 young (20–32 years, seven women) and 12 older adults (70–90 years, six women) in conditions mimicking quiescent muscle and a range of elevated H+ (pH 6.8–6.6–6.2) and Pi (12–20–30 mm). The older adult knee extensor muscles showed hallmark signs of ageing, including 19% lower thigh lean mass, 60% lower power and a greater fatigability compared to young adult muscles. Progressively increasing concentrations of H+ and Pi in the chemically‐permeabilized fibre experiments caused a linear decrease in fibre force, velocity and power; however, the effects did not differ with age or sex. Fast fibre cross‐sectional area was 41% smaller in older compared to young adults, which corresponded with lower absolute power. Size‐specific power was greater in fibres from older compared to young adults, indicating the age‐related decline in absolute power was explained by differences in fibre size. These data suggest the age‐related loss in power is determined primarily by fast fibre atrophy in men and women, but the age‐related increase in fatigability cannot be explained by an increased sensitivity of the cross‐bridge to H+ and Pi. The causes of the age‐related loss in muscle power output and the increase in fatigability during dynamic exercise remain elusive. We show that progressively increasing concentrations of hydrogen (H+) and inorganic phosphate (Pi) causes a linear decrease in muscle fibre force, velocity and power, but the depressive effects of these metabolites on cross‐bridge function did not differ in fibres from older compared to young adults across a range of fatigue‐mimicking conditions. We also found peak absolute power did not differ in slow fibres from young and older adults but it was ∼33% lower in older adult fast fibres, which was explained entirely by age differences in fibre size. These data suggest that fast fibre atrophy is a major factor contributing to the loss in power of older men and women, but that the age‐related increase in fatigability cannot be explained by an increased sensitivity of the cross‐bridge to H+ and Pi. [ABSTRACT FROM AUTHOR]

ABSTRACT We developed an assist robot that changes its assist force in real time according to the lumbar load estimated from the load information on the hand measured using a hand sensor device and the posture information. Furthermore, using the developed assist robot, the effect of the load‐following control on muscle fatigue was verified. The load was set at 6 and 1 kgf, and the amount of muscle activity in the lumbar region was measured using a muscle potential sensor during continuous flexion–extension exercises. The central frequency of the power spectrum was calculated as muscle fatigue, and its time trend was obtained. For comparison, similar experiments were also conducted without an assistive robot and with an existing assistive robot. Consequently, when load‐following control was used, muscle fatigue was reduced compared with existing assist robots in which the assist force was excessive in relation to the load. This shows the importance of load‐following control that is necessary to control the assist force according to the load when the assist robot is worn during work in which the load changes in a complex manner. [ABSTRACT FROM AUTHOR]

Background: Physical exercise is an important method for both the physical and mental health of the senior population. However, excessive exertion can lead to increased risks of falls, severe injuries, and diminished quality of life. Therefore, simple and effective methods for fatigue monitoring during exercise are highly desirable, particularly in community settings. The purpose of this study was to explore the possibility of real-time detection of exercise-induced fatigue using surface Electromyogram (sEMG) features, including the kurtosis and skewness of the Probability Density Function (PDF) in the community settings to solve the issues of low sensitivity and high computational complexity of commonly used sEMG features. Methods: sEMG signals from six forearm muscles were recorded during hand grip tasks at 20% maximal voluntary contraction (MVC) task-to-failure contractions from 30 healthy community-dwelling elders at their respective community centers. PDF shape features of the sEMG, namely kurtosis and skewness, were computed from 25 s of non-fatigue stable phase and 25 s of fatigue data for comparison. Statistical tests were conducted to compare and test for the significance of these features. We further proposed a novel fatigue indicator, Temporal-Mean-Kurtosis (TMK) of channel-averaged kurtosis, to detect fatigue with relatively low computational complexity and adequate sensitivity in community settings. ANOVA and post-hoc analyses were performed to examine the performance of TMK. Results: Statistically significant differences were found between the non-fatigue period and the fatigue period for both kurtosis and skewness, with increasing values when approaching fatigue. TMK was shown to be sensitive in detecting fatigue with respect to time with lower computational complexity than the Sample Entropy. Conclusion: This study investigated PDF shape features of sEMG signals during a handgrip exercise to identify muscle fatigue in older adults in community experiments. Results revealed significant changes in kurtosis upon fatigue, indicating that PDF shape features were suitable convenient detectors of muscle fatigue in community experiments. The proposed indicator, TMK, showed potential sensitivity in tracking muscle fatigue over time in community-based settings with limited computational complexity, highlighting the promise of sEMG's PDF features in detecting muscle fatigue among the elderly. [ABSTRACT FROM AUTHOR]

Objective: To explore the neuromuscular control mechanism and quantifying the fatigue response during bench press exercise is important references to prescribe an appropriate exercise program. However, current literature struggles to provide a concrete conclusion on the changes of intermuscular EMG-EMG coupling between synergistic and antagonist muscles during the exercise. Thus, the current study was designed to reveal fatigue-related changes of intermuscular EMG-EMG coupling during bench press exercise. Methods: Thirty-one healthy male participants performed a bench press exercise on the Smith machine at 60% One Repetition Maximum (1RM) workload to exhaustion, while surface electromyographic signals (sEMG) were collected from triceps brachii (TB), biceps brachii (BB), anterior deltoid (AD), posterior deltoid (PD), and pectoralis major (PM). Surface EMG signals were divided into the first half and second half of the bench press exercise. Phase synchronization index (PSI) was calculated between sEMG of synergistic muscle pairs AD-TB, AD-PM and antagonist muscle pairs BB-TB, AD-PD. Results: EMG power of TB, AD, PD, PM muscles in alpha (8–12 Hz) frequency band and EMG power of each muscle in beta (15–35 Hz), and gamma (35–60 Hz) frequency bands were all increased during the second half of contraction compared with the first half of contraction. PSI of gamma frequency band was significantly decreased in BB-TB muscle pair while EMG-EMG coupling of AD-TB in gamma frequency band was significantly increased during the second half of contraction compared to the first half of contraction. Conclusions: The results indicated a decrease of interconnection between synchronized cortical neurons and the motoneuron pool of BB and TB, and an increase of interconnection between AD-TB muscles during fatiguing bench press exercise at 60% 1RM workload. The changes of intermuscular coupling may be related to the supraspinal modulations to compensate for the decrease of muscle force as well as a result of unbalanced changes of agonist and antagonist muscle contractility. [ABSTRACT FROM AUTHOR]

Kettlebell swings (KBSs) are commonly used to target the lumbar erector spinae and lower body musculature. This exercise exhibits distinct loading properties that requires cyclical contraction of the trunk extensors and posterior chain, potentially explaining its novel influence on muscle contractility. Tensiomyography (TMG) is a reliable, noninvasive, passive technique that may be used to examine muscular fatigue produced by exercises such as KBSs. The purpose of this randomized control trial was to determine the extent of muscle fatigue in the lumbar erector spinae musculature following the performance of a previously published high-intensity interval KBS protocol. Forty-one adults between the ages of 18 and 45 years were recruited. Inclusion criteria included subjects with no recent history of low back pain and clearance by the physical activity readiness questionnaire. Subjects were randomly allocated to either a KBS group (n 5 21) or a control group (CON; n 5 20) who only performed the unloaded warm-up. Subjects were assessed at baseline, postintervention, and 24-hours postintervention for bilateral erector spinae fatigue, measured by 5TMGparameters (Dm, Tc, Tr, Td, and Ts). The results were evaluated through a 233 (group 3 time) repeated-measures analysis of variance. The level of significance was set at p # 0.05. There was no significant difference in lumbar erector spinae fatigue, measured by the 5 TMG parameters (p $ 0.079), following the interval KBS protocol in comparison with the CON group at 3 assessment periods. A high-intensity interval KBS protocol failed to produce significant differences in erector spinae fatigue compared with the control group that did not perform a KBS. These findings warrant further investigation into muscle fatigue produced with higher intensity protocols and possibly suggest, depending on the programming goals, the need for an alternate KBS training parameters. [ABSTRACT FROM AUTHOR]

Objectives: Rupture of the anterior cruciate ligament (ACL) is a severe injury common in sports. It also has a high rate of re-injury. The aim of this work was to assess hamstring muscle fatigue in active football players after ACL reconstruction who were cleared to play and to determine symmetry between the lateral and medial hamstring muscles. Methods: In professional football players post ACL reconstruction (n = 25) and non-injured players (n = 26), the bioelectrical activity of the medial (biceps femoris—BF) and lateral (semimembranosus and semitendinosus—SEM) hamstring muscles was measured during 60 s of isometric contraction. The fatigue variables were calculated using the Continuous Wavelet Transform (CWT) tool. Results: The football players following ACL reconstruction demonstrated significant asymmetry in fatigue of the lateral and medial hamstring muscles, with greater fatigue in the SEM compared to the BF muscle. Moreover, in those after reconstruction, the changes are more pronounced, with higher muscle fatigue in both limbs (they have lower MDF than non-injured players) and more severe SEM muscle insufficiency (noted in both limbs but with greater intensity in the non-operated one). Conclusions: The higher SEM muscle fatigue observed in this study influenced the lateral-to-medial activation ratio within the hamstring muscle, which may be a probable cause of this muscle's insufficiency in laterally stabilizing the knee in the frontal and transverse plane. Furthermore, the hamstring muscles after reconstruction were more fatigued in both limbs, which may be another risk factor for ACL graft rupture. Therefore, increased fatigue in specific hamstring muscles may indicate the direction in which knee stabilization is compromised due to ACL overload. A muscle that becomes fatigued and inefficient more quickly also becomes ineffective in performing its function sooner, which can lead to increased overloading forces acting on the ACL graft. [ABSTRACT FROM AUTHOR]

Inappropriate kitchen cooking height may lead to uncomfortable and muscle fatigue. This study aims to compare the effects of kitchen cooking height on upper limb muscle activation, posture, and perceived discomfort among different age groups. Fifteen older women and fifteen young Chinese women each completed three consecutive 20 s simulated cooking tasks at five different heights. Surface electromyography, motion capture, and Borg CR10 scale were used to measure muscle loading. Results showed that the main power muscles of the cooking task were the anterior deltoid, brachioradialis, and biceps brachii. The higher muscle contribution rate of biceps brachii and triceps brachii was found in the younger group compared to the older group (p < 0.05). Muscle activation of the anterior deltoid (different in 1.28–2.87%), pectoralis major (different in 1.43–1.69%), and erector spinae (different in 0.6–1.21%), as well as right shoulder abduction (different in 5.91°–7.96°), were significantly higher in older group than in young group (p < 0.05). Muscle activation of the anterior deltoid and right shoulder abduction decreased significantly with decreasing height (p < 0.05). A height of 200–250 mm below the elbow was considered a more comfortable cooking height for both age groups. This provides data to support the design of cabinet sizes. [ABSTRACT FROM AUTHOR]

The aim was to analyse the consequences of a congested schedule (due to the COVID-19 lockdown) on creatine kinase (CK) in elite football players using GPS tracking technology. A total of 17 elite football players were monitored in training and competition with a global positioning system. Variables including total distance, high-intensity distance, and distance acceleration and deceleration were analysed. Different measurements of serum creatine kinase (CK) concentration were performed on match day (MD) and at 24 h (MD+1), 48 h (MD+2), and 72 h (MD+3) after each match to study the muscle damage of each individual player caused during the match. The results showed a significant increase in physical demands in training (in relative terms regarding the match) at MD+3 compared to MD+1 and MD+2. Furthermore, at +72 h, CK decreases to a value almost the same as that before MD. On the other hand, the players with lower demands for high-intensity actions in the match showed a higher reduction in the concentration of CK at MD+3 compared to MD+1 and MD+2 (p < 0.05). It became evident that players with high-intensity demand and a high number of accelerations and decelerations need more time to assimilate the match load and can remain in a state of muscle fatigue for up to 3 days. In addition, a congested schedule can lead to a state of chronic fatigue in elite football players, limiting physical performance and possibly increasing the potential risk of injury for football players. [ABSTRACT FROM AUTHOR]

Aim: To assess the feasibility of video game-based trunk exercises using the Valedo® system in a chronic stroke population. Method: Ten chronic stroke survivors (eight males and two females, mean age 63 ± 15 years) were asked to complete 18 intervention sessions, each lasting 45 min., over 6–8 weeks. Feasibility was evaluated quantitatively using the Psychosocial Impact of Assistive Devices Scale (PIADS) as well as through recruitment, retention, adherence, and safety measures. Qualitative data on feasibility were collected through post-intervention semi-structured interviews. Descriptive analysis was used to summarize participant characteristics, recruitment, retention, and adherence. Qualitative data were analyzed using thematic analysis of the interviews. Results: Twelve stroke survivors were recruited from Southampton (United Kingdom) and Riyadh (Kingdom of Saudi Arabia), with two participants dropping out after the baseline assessment session. The remaining ten participants completed the study with a mean adherence of 96.11% to the planned sessions. No serious adverse effects were reported, however, four participants did experience trunk muscle tightness and fatigue. Post-intervention interviews revealed that participants encountered some physical and cognitive challenges while playing the Valedo video games. However, they felt that the implementation of trunk exercises using video games was safe, as the exercises were performed in a secure environment and in safe positions. Conclusions: The findings suggest that the Valedo system is feasible for delivering trunk exercises to chronic stroke survivors. Several factors should be considered when implementing this type of intervention in the future. [ABSTRACT FROM AUTHOR]

The effects of acute dehydration on neuromuscular function have been studied. However, whether the mechanisms underpinning such function are central or peripheral is still being determined, and the results are inconsistent. This systematic review aims to elucidate the influence of acute dehydration on neuromuscular function, including a novel aspect of investigating the central and peripheral neuromuscular mechanisms. Three databases were used for the article search: PubMed, Web of Science, and Scopus. Studies were included if they had objective measurements of dehydration, muscle performance, and electromyography data or transcranial magnetic stimulation or peripheral nerve stimulation measurements with healthy individuals aged 18–65 years. Twenty-three articles met the eligibility criteria. The studies exhibited considerable heterogeneity in the methods used to induce and quantify dehydration. Despite being inconsistent, the literature shows some evidence that acute dehydration does not affect maximal strength during isometric or moderate-speed isokinetic contractions. Conversely, acute dehydration significantly reduces maximal strength during slow-speed isokinetic contractions and fatigue resistance in response to endurance tasks. The studies report that dehydration does not affect the motor cortical output or spinal circuity. The effects occur at the peripheral level within the muscle. [ABSTRACT FROM AUTHOR]

We investigated whether the strength of oscillations in common synaptic input was explanatory of knee extensor (KE) torque signal complexity during fresh and fatigued submaximal isometric contractions, in adults aged from 18 to 90 years. The discharge times of motor units were derived from the vastus lateralis muscle of 60 participants using high‐density surface EMG, during 20 s isometric KE contractions at 20% of maximal voluntary contraction, performed before and after a fatiguing repeated isometric KE contraction protocol at 60% of maximal voluntary contraction. Within‐muscle coherence Z‐scores were estimated using frequency‐domain coherence analysis, and muscle torque complexity was assessed using multiscale entropy analysis and detrended fluctuation analysis. Alpha band (5–15 Hz) coherence was found to predict 23.1% and 31.4% of the variance in the complexity index under 28‐scales (CI‐28) and detrended fluctuation analysis α complexity metrics, respectively, during the fresh contractions. Delta, alpha and low beta band coherence were significantly increased due to fatigue. Fatigue‐related changes in alpha coherence were significantly predictive of the fatigue‐related changes in CI‐28 and detrended fluctuation analysis α. The fatigue‐related increase in sample entropy from scales 11 to 28 of the multiscale entropy analysis curves was significantly predicted by the increase in the alpha band coherence. Age was not a contributory factor to the fatigue‐related changes in within‐muscle coherence and torque signal complexity. These findings indicate that the strength of alpha band oscillations in common synaptic input can explain, in part, isometric KE torque signal complexity and the fatigue‐related changes in torque signal complexity. What is the central question of this study?Can the strength of oscillations in common synaptic input explain the complexity of isometric knee extensor torque signals?What is the main finding and its importance?Stronger alpha band oscillations in common synaptic input were associated with isometric knee extensor torque signals of higher complexity. Fatigue‐related changes in the torque signal complexity were associated with the fatigue‐related changes in the strength of alpha band oscillations in common synaptic input. These findings suggest that the complexity measures derived from isometric knee extensor torque signals reflect the neural mechanisms underpinning the modulation of torque control. [ABSTRACT FROM AUTHOR]

Introduction: This study investigated the magnitude and etiology of neuromuscular fatigue and muscle damage induced by eccentric cycling compared with conventional concentric cycling in patients with breast cancer. Methods: After a gradual familiarization protocol for eccentric cycling, nine patients with early-stage breast cancer performed three cycling sessions in eccentric or concentric mode. The eccentric cycling session (ECC) was compared with concentric cycling sessions matched for power output (CONpower; 80% of concentric peak power output, 95 ± 23 W) or oxygen uptake (CONV̇O2 ; 10 ± 2 mL·min·kg-1). Preexercise to postexercise changes (30-s through 10-min recovery) in knee extensor maximal voluntary contraction force (MVC), voluntary activation, and quadriceps potentiated twitch force (Qtw) were quantified to determine global, central, and peripheral fatigue, respectively. Creatine kinase and lactate dehydrogenase activities were measured in the plasma before and 24 h after exercise as markers of muscle damage. Results: Compared with CONpower (-11% ± 9%) and CONV̇O2 (-5% ± 5%), the ECC session resulted in a greater decrease in MVC (-25% ± 12%) postexercise (P < 0.001). Voluntary activation decreased only in ECC (-9% ± 6% postexercise, P < 0.001). The decrease in Qtw was similar postexercise between ECC and CONpower (-39% ± 21% and -40% ± 16%, P > 0.99) but lower in CONV̇O2 (P < 0.001). The CONpower session resulted in twofold greaterV̇O2 compared with the ECC and CONV̇O2 sessions (P < 0.001). No change in creatine kinase or lactate dehydrogenase activity was reported from preexercise to 24 h postexercise. Conclusions: The ECC session induced greater neuromuscular fatigue compared with the concentric cycling sessions without generating severe muscle damage. ECC is a promising exercise modality for counteracting neuromuscular maladaptation in patients with breast cancer. [ABSTRACT FROM AUTHOR]

Background: Functional electrical stimulation (FES) cycling has been reported to enhance muscle strength and improve muscle fatigue resistance after spinal cord injury (SCI). Despite its proposed benefits, the quantification of muscle fatigue during FES cycling remains poorly documented. This study sought to quantify the relationship between the vibrational performance of electrically‐evoked muscles measured through mechanomyography (MMG) and its oxidative metabolism through near‐infrared spectroscopy (NIRS) characteristics during FES cycling in fatiguing paralyzed muscles in individuals with SCI. Methods: Six individuals with SCI participated in the study. They performed 30 min of FES cycling with MMG and NIRS sensors on their quadriceps throughout the cycling, and the signals were analyzed. Results: A moderate negative correlation was found between MMG root mean square (RMS) and oxyhaemoglobin (O2Hb) [r = −0.38, p = 0.003], and between MMG RMS and total hemoglobin (tHb) saturation [r = −0.31, p = 0.017]. Statistically significant differences in MMG RMS, O2Hb, and tHb saturation occurred during pre‐ and post‐fatigue of FES cycling (p < 0.05). Conclusions: MMG RMS was negatively associated with O2Hb and muscle oxygen derived from NIRS. MMG and NIRS sensors showed good inter‐correlations, suggesting a promising use of MMG for characterizing metabolic fatigue at the muscle oxygenation level during FES cycling in individuals with SCI. [ABSTRACT FROM AUTHOR]

This study aimed to systematically review and summarise the evidence about the effect of muscle fatigue on the knee proprioception of trained and non-trained individuals. A search in PubMed, Scopus, Web of Science and EBSCO databases and Google Scholar was conducted using the expression: "fatigue" AND ("proprioception" OR "position sense" OR "repositioning" OR "kinesthesia" OR "detection of passive motion" OR "force sense" OR "sense of resistance") AND "knee". Forty-two studies were included. Regarding joint-position sense, higher repositioning errors were reported after local and general protocols. Kinesthesia seems to be more affected when fatigue is induced locally, and force sense when assessed at higher target forces and after eccentric protocols. Muscle fatigue, both induced locally or generally, has a negative impact on the knee proprioception. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effectiveness of passive back-support exosuit on postural control and cognitive performance during a fatigue-inducing posture maintenance task. Background: Wearable support systems (exoskeletons/exosuits) reduce physical demands but may also influence postural control and cognitive performance by reducing muscular fatigue. Method: Eighteen participants visited on two different days to test an exosuit system and performed dual-task cognitive assessments based on human information processing (information acquisition, information integration, and action implementation) while maintaining a 35° trunk flexion posture for 16 minutes. Center-of-pressure (CoP), cognitive performance, and perceived workload were recorded, while erector spinae muscle activity was captured to quantify muscle fatigue. Results: The exosuit was effective in reducing erector spinae muscle fatigue during the static posture maintenance task (61% less in Δmedian frequency: −9.5 Hz (EXO-Off) versus −3.7 Hz (EXO-On)). The fatigue-inducing task increased CoP velocity as a function of time (29% greater: 9.3 mm/sec (pre) versus 12.0 mm/sec (post)), and exosuit use decreased CoP velocity (23% less: 12.1 mm/sec (EXO-Off) versus 9.4 mm/sec (EXO-On)). The exosuit was also effective at mitigating cognitive degradation, as evidenced by a higher hit-to-signal ratio (8% greater: 81.3 (EXO-Off) versus 87.9 (EXO-On)) in the information integration task and reducing perceived workload in all stages of human information processing. Conclusion: Exosuit provided benefits of postural control and information integration processing during a 16-min static posture maintenance task. Application: Torso exoskeletons/suits can have positive implications for occupations with concurrent physical and cognitive demands. [ABSTRACT FROM AUTHOR]

Objective: To examine the effect of concurrent physical and cognitive demands as well as age on indicators of muscle fatigue at the wrist. Background: There are few studies examining risk indicators for musculoskeletal disorders associated with work-related physical and cognitive demands that often occur simultaneously in the workplace. Methods: Twenty-four gender-balanced older and 24 gender-balanced younger (mean age 60 and 23 years) participants performed four 30 min dual tasks. Tasks differed by the muscular load level during force tracking: 5% and 10% of maximum voluntary contraction force (MVC) and concurrent cognitive demands on the working memory: easy and difficult. Muscle fatigue was assessed by MVC decline and changes in surface electromyography (increased root mean square: RMS, decreased median frequency: MF) at the extensor digitorum (ED) and extensor carpi ulnaris (EU). Results: A decline in MVC was found in all participants when tracking was performed at 10% MVC (mean ± SD: 137.9 ± 49.2 – 123.0 ± 45.3 N). Irrespective of age, muscular, or cognitive load, RMS increased (ED 12.3 ± 6.5 – 14.1 ± 7.0% MVE, EU 15.4 ± 7.6 – 16.9 ± 8.6% MVE) and MF decreased (ED 85.4 ± 13.6 – 83.2 ± 12.8 Hz, EU 107.2 ± 17.1 – 104.3 ± 16.7 Hz) in both muscles. However, changes in MF of EU tended to be more pronounced in the older group at higher cognitive and lower muscular load, without reaching statistical significance. Conclusion: Maximum voluntary contraction indicated no interaction between muscle fatigue, cognitive load, or age. However, the tendencies toward altered muscle activity due to an increase in cognitive load and older age suggest muscular adaptations while maintaining tracking performance during the onset of fatigue signs in the sEMG signal. Application: If the tendencies in muscle activity are confirmed by further studies, ergonomic assessments in industrial workplaces should consider cognitive load and age when describing the risk of musculoskeletal disorders. [ABSTRACT FROM AUTHOR]

Aim: The study aims to analyze the current scientific literature on risk factors and strategies for the prevention of muscle cramps that occur during physical activity. Particular attention is paid to muscle fatigue, dehydration, electrolyte balance, and other neurophysiological and metabolic aspects that can trigger cramps. Materials and methods: To achieve the objectives of the research, an overview of scientific publications extracted from databases such as PubMed, Scopus, Medline and Google Scholar was carried out, with a main focus on research published in recent years. Keywords such as "muscle cramps", "physical activity", "prevention" and "risk factors" were used. Conclusion: The study confirms that muscle cramps are a complex phenomenon influenced by multiple factors, including muscle fatigue, dehydration, electrolyte balance disorders, and metabolic changes. It emphasizes the importance of adequate hydration, electrolyte balance, proper exercise program and techniques such as stretching and massage for the prevention and management of muscle cramps. It is advisable to continue research in the field to develop effective strategies to prevent these frequent and painful spasms that occur during or after physical activity. [ABSTRACT FROM AUTHOR]

Purpose: The few previous researches on the impact of calf compression garments (CG) on running performance while assessing physiological and perceptual factors. Therefore, this study investigated how the clothing pressure of two types of Calf CG, CG1 and CG2, affects muscle fatigue and activation during running. Design/methodology/approach: Five healthy amateur runners(three female and two male)were recruited for a 30-min running trial. They wear a Calf CG on their right leg (CG group), but not on their left leg(CON group). After obtaining the clothing pressure of Calf CG on the gastrocnemius lateral head (GL), gastrocnemius medial head (GM) and tibialis anterior(TA) of the right leg, surface electromyography (sEMG)of four muscles of GL, GM, TA and rectus femoris (RF) of the left and right legs were measured during running, and heart rate, cardiopulmonary rate, and human RPE were also measured. Blood bleed oxygen before and after the running trial were measured. The root mean square (RMS) of the characteristic values was selected as an index for the analysis of sEMG signals, and the data were analyzed using statistical and computational methods. Findings: The results showed that the indexes of heart rate, blood oxygen, and RPE were significantly increased, indicating that the subjects had reached the fatigue level. The comparison of mean clothing pressure at GL, GM and TA locations reveals that the TA location consistently exhibits the highest pressure for both types of CG. When wearing CG1, the mean clothing pressure at the GL and GM test points is greater than that of CG2(CG1-GL = 0.2059 kPa > CG2-GL = 0.148 kPa; CG1-GM = 0.1633 kPa > CG2-GM = 0.127 kPa). This is attributed to the double-layered fabric on the sides of CG1, which precisely covers the GL and GM areas, thereby resulting in higher mean clothing pressure at these locations compared to CG2. Conversely, the mean clothing pressure at the TA location for CG1 is lower than that for CG2(CG1-TA = 0.3852 kPa < CG2-TA = 0.426 kPa). The pressure exerted by the CG1 on the lower limb test areas has both positive and negative effects, though neither are statistically significant. The pressure exerted by CG2 alleviates fatigue at the directly affected locations GL and GM, but exerts excessive pressure on TA, resulting in a negative effect. Additionally, CG2 pressure alleviates fatigue at the indirectly affected location RF on the same side. Based on the specific clothing pressure data, it is concluded that when the pressure at the GM location is 0.127 kPa, 30 min of running has a fatigue-relieving effect. However, the pressure should not be excessively high, at 0.1633 kPa it exhibits an insignificant adverse effect. At the TA location, a garment pressure mean between 0.3852 and 0.426 kPa does not alleviate fatigue after 30 min of running, and the negative effect becomes more pronounced as the pressure increases. The pressure exerted by the CG at GL, GM, TA and RF locations shows significant changes from the previous time period during the 15–18 min interval after running. Therefore, in the design of CG, attention should be paid to the changes in clothing pressure effects on muscles during this specific time period. Originality/value: The few previous researches on the impact of calf compression garments (CG) on running performance while assessing physiological and perceptual factors. Therefore, this study investigated how the clothing pressure of two types of Calf CG, CG1 and CG2, affects muscle fatigue and activation during running. [ABSTRACT FROM AUTHOR]

Background: Hamstring (HS) strength deficits and imbalances have been identified as risk factors for sustaining anterior cruciate ligament (ACL) injuries and muscular strains, with HS injuries being the most prevalent muscle injuries in soccer athletes. The aim of this study was to investigate HS eccentric strength before and after a soccer match in both male and female soccer athletes. Hypothesis: Soccer athletes have changes in eccentric HS strength after a soccer game. Study Design: Cohort observational study. Level of Evidence: Level 3. Methods: HS eccentric strength (mean and absolute peak torque and total work) was measured in 64 healthy male and female competitive football athletes (14-25 years) with an automatic device during the execution of the Nordic hamstring exercise (NHE) test before and after a 90-minute soccer match. The anterior-knee laxity (AKL) was quantified with an arthrometer. Results: Mean and absolute eccentric HS peak torque decreased by 24.5 N.m (-12.34%; P < 0.01) and 21.9 N.m (-10.08%; P < 0.01) in female athletes, whereas their male peers improved by 19.9 N.m (+9.01%; P = 0.01) and by 20.9 N.m (+8.51%; P = 0.02), respectively. HS total work in female athletes decreased by 831.1 J (P < 0.01) compared with the male athlete reduction of 235.3 J. Both the pre- versus postmatch intersex mean and absolute eccentric HS peak torque changes were significant (P < 0.01), as were the changes in HS total work (P < 0.01). The pre- versus postmatch AKL difference and the dominant versus nondominant limb comparison of the strength parameters were not significantly different. Younger female athletes (14-19 years old) presented a greater decrease in mean and absolute peak HS eccentric strength compared with those in older female athletes and men. Conclusion: HS eccentric strength and work differ based on athlete sex, as measured by the NHE test. Mean peak, absolute peak, and total work showed greater reductions in female athletes than those in their male peers. The subgroup of 14- to 19-year-old female athletes experienced the highest reduction in strength parameters. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the effects of contrast heat and cold pressure therapy (CHCP) on muscle tone, elasticity, stiffness, perfusion unit, and muscle fatigue indices after plyometric training consisting of five sets of jumping on a 50-cm high box until exhaustion. A prospective, randomized, controlled single-blind study design was used. Twenty professional MMA fighters were included in the study. The experimental group (n = 10) was subjected to the CHCP protocol (eGR), while the control group (cGR) (n = 10) was subjected to sham therapy. Both protocols consisted of three CHCP sessions performed immediately after plyometric exercise, 24 and 48 h afterwards. Measurements were taken at the following time points: 1) at rest; 2) 1 min post-exercise; 3) 1 min post-CHCP therapy; 4) 24 h post-CHCP therapy; 5) 48 h post-CHCP therapy. The results of the eGR compared to the cGR showed significantly higher perfusion at time point 5 (p < 0.001), higher muscle tone at time points 1, and 3-5 (p < 0.001 for all), higher stiffness at time points 1, 3-5 (p < 0.001 for all) and a higher pain threshold at time points 1 and 5 (p < 0.001 for all). This study suggests a positive effect of CHCP therapy on muscle biomechanics, the pain threshold, and tissue perfusion, which may contribute to increasing the effectiveness of post-exercise muscle recovery in MMA athletes. [ABSTRACT FROM AUTHOR]

Limb‐girdle muscular dystrophies (LGMDs) constitute a diverse group of inherited disorders primarily affecting skeletal muscle. Despite the absence of cures, rehabilitative treatments offer potential for preventing and mitigating loss of muscle strength. However, the role of exercise training in LGMD patients remains contentious. This review aims to provide an overview of the currently available motor rehabilitation strategies for the most common subtypes of LGMD. To identify relevant articles, we performed a systematic search in PubMed, Embase, Cochrane Library, and Web of Science, focusing on muscular and respiratory interventions. The search resulted in 560 potentially relevant articles, of which 16 were included in the review. Eight studies concentrated on neuromuscular functional rehabilitation therapy programs, seven combined both neuromuscular rehabilitation and interventions to maintain or enhance respiratory functionality and one focused on respiratory intervention only. Altogether, the papers examined offered a comprehensive view on the rehabilitative strategies available and provided an indication of the most valuable practices to deal with patients' health and needs. Upon analysis, we conclude that, when tailored to individual needs, muscle training can enhance strength and functional abilities, positively impacting psychological well‐being. However, generic protocols may lead to limited benefits, fatigue, pain, and compliance issues. Moreover, early management of respiratory symptoms and personalized respiratory physiotherapy can enhance patients' well‐being and their capability to participate in muscle training exercises. Future studies should not only refine rehabilitation approaches but also assess their impact on patients' quality of life, including psychological factors like depression and self‐esteem. [ABSTRACT FROM AUTHOR]

\nSummary boxOver the past decade, numerous studies have investigated an innovative “live low-train high” approach based on the repetition of short (<30 s) “all-out” sprints with incomplete recoveries in hypoxia; the so-called Repeated-Sprint training in Hypoxia (RSH). The aims of the present review are therefore threefold. First, this study summarizes the available evidence on putative additional performance enhancement after RSH comparing to the same training in normoxia (RSN). Second, a critical analysis of underpinning mechanisms discusses how advantages can be obtained through RSH for sea-level performance enhancement. An enhanced microcirculatory vasodilation leading to improved muscle perfusion and/or oxygenation and an increase in muscular phosphocreatine content may help explain the superiority of RSH vs. RSN. Third, the present review aims to provide guidelines for coaches, athletes and scientists to apply RSH interventions with regard to the interval duration, exercise-to-rest ratio and training volume. In conclusion, this review supports repeated-sprint training in hypoxia as an efficient (but not magic) training intervention with 77% of the controlled studies reporting an additional benefit with added hypoxia, mainly for team-, combat- and racket-sports athletes but also for all other sports (e.g. endurance) that require repeated accelerations with lesser fatigue. This review critically analyzes the results of the studies involving repeated-sprint training in hypoxia (RSH) since 2013.10 years ago, RSH was proposed as a promising training strategy shown to delay muscle and metabolic fatigue, particularly during repeated-sprint exercises with incomplete recoveries.In the past decade, RSH has gained great popularity among athletes, coaches and scientists as an effective training reproduced in various sports with a large majority of studies reporting beneficial outcomes.RSH may improve performance in a fibre-type-selective and intensity-dependent manner, with mechanisms presumably different than those associated with other (less intense) hypoxic training methods.This review critically analyzes the results of the studies involving repeated-sprint training in hypoxia (RSH) since 2013.10 years ago, RSH was proposed as a promising training strategy shown to delay muscle and metabolic fatigue, particularly during repeated-sprint exercises with incomplete recoveries.In the past decade, RSH has gained great popularity among athletes, coaches and scientists as an effective training reproduced in various sports with a large majority of studies reporting beneficial outcomes.RSH may improve performance in a fibre-type-selective and intensity-dependent manner, with mechanisms presumably different than those associated with other (less intense) hypoxic training methods. [ABSTRACT FROM AUTHOR]

Background: Exercise-induced oxidative stress and inflammation can impair muscular function in humans. The antioxidant and anti-inflammatory properties of molecular hydrogen (H2) highlight its potential to be as an effective nutritional supplement to support muscular function performance in healthy adults. However, the effects of H2 supplementation on muscular endurance performance in trained individuals have not been well characterized. This study aimed to assess the effects of intermittent hydrogen-rich water (HRW) supplementation before, during, and after resistance training on muscular endurance performance, neuromuscular status, and subjective perceptual responses after a 48-h recovery period. Methods: This randomized, double-blinded, placebo-controlled cross-over study included 18 trained men aged 19.7 ± 0.9 years. Participants in this study were instructed to consume 1,920 mL of HRW or pure water (Placebo) daily for 7 days. Additionally, participants were required to supplement with HRW or pure water five times during the training day (1,260 mL total). This included drinking 210 mL 30 min and 1 min before training, 210 mL between training sets, 210 mL immediately after training, and 420 mL 30 min into the recovery period. Participants performed half-squat exercises with the load set at 70% of one repetition maximum for six sets (half-squat exercise performed to repetitions failure each set). We measured the power output and number of repetitions in the free barbell half-squat used to assess muscular endurance performance in participants. The countermovement jump (CMJ) height, total quality recovery scale (TQRS), and muscle soreness visual analog scale (VAS) scores were measured to assess fatigue recovery status after training, as well as at 24 and 48 h of recovery. Results: The total power output (HRW: 50,866.7 ± 6,359.9W, Placebo: 46,431.0 ± 9,376.5W, p = 0.032) and the total number of repetitions (HRW:78.2 ± 9.5 repetitions, Placebo: 70.3 ± 9.5 repetitions, p = 0.019) in the H2 supplemented group were significantly higher than in the placebo group. However, there was no statistically significant difference (p< 0.05) between the H2 and placebo groups in CMJ, TQRS, and VAS. Conclusion: Eight days of intermittent HRW intake could significantly improve muscular endurance performance in trained individuals, making it a promising strategy for athletes or fitness enthusiasts looking to boost muscular endurance during resistance training or competitions. However, it should be noted that HRW intake alone may not be adequate to accelerate recovery from muscle soreness or fatigue following high-intensity training. [ABSTRACT FROM AUTHOR]

Background: Sympathetic nervous system hyperactivity and chronic intermittent nocturnal hypoxia in individuals with obstructive sleep apnea (OSA) predispose them to microvascular impairment, which may contribute to increased daytime muscle fatigue. This study aimed to assess microvascular reactivity of the skeletal muscle, examine fatigability, and determine the relationship between fatigability and microvascular reactivity in adults with OSA. Methods: Twenty-six participants were allocated into two groups—those with OSA and those without i.e. non-OSA. Each group comprised of 13 individuals who underwent an arterial occlusion test on their non-dominant leg. The percentage change of maximal hyperemic response (MHR) and the time to achieve MHR (tM) of both the total myoglobin/hemoglobin (∆[Hbtot]) and the oxygenated myoglobin/hemoglobin (∆[HbO2]) signals from near-infrared spectroscopy were calculated to examine microvascular reactivity. In addition, a 10-min walk test was performed to assess performance and perceived fatigability. Results: The OSA group demonstrated a reduced in ∆[Hbtot]MHR (150.9 ± 16.2% vs. 235.8 ± 72.7%, p = 0.006), ∆[HbO2]MHR (131.4 ± 8% vs. 161.7 ± 10.6%, p = 0.001) and increased ∆[Hbtot]tM (80.5 ± 13.1 s vs. 47.7 ± 9.9 s, p < 0.001), ∆[HbO2]tM (85.2 ± 22.4 s vs. 52.1 ± 5.9 s, p = 0.001) compared to the non-OSA group. In addition, participants in the OSA group experienced greater perceived (6 ± 1 vs. 2.8 ± 0.1, p = 0.001) and performance fatigability (1.1 ± 0.1 vs. 0.9 ± 0.1, p = 0.001) compared to adults in the non-OSA group. Moreover, both performance and perceived fatigability were significantly associated with microvascular reactivity parameters (all p < 0.05). Conclusion: Microvascular dysfunction, as determined by an attenuated post-occlusive reactive hyperemia, is observed in individuals with OSA that may contribute to increased fatigability in these individuals. [ABSTRACT FROM AUTHOR]

In recent years, ischemic preconditioning (IPC) has garnered significant attention in sports research. While IPC has demonstrated positive effects in high-intensity sports such as judo and swimming, its potential benefits for enhancing the performance of Taekwondo athletes have not been extensively studied. This study aimed to investigate the effects of IPC on taekwondo performance and to observe the metabolic characteristics associated with enhancing sports performance via LC‒MS/MS-based plasma metabolomics. Seventeen participants underwent the repeated frequency speed of kick test (FSKT) after IPC, along with pre- and post-exercise plasma metabolite analysis. Differential abundance metabolite analysis, enriched pathway analysis, and weighted gene coexpression network analysis (WGNCA) were employed to delve into metabolic characteristics. The findings highlighted a significant enhancement in FSKT performance in the experimental group. Metabolomic analysis revealed 109 differentially abundant metabolites, including Dl-lactate, hypoxanthine, acetylcarnitine, and acetylsalicylic acid. Enriched pathway analysis revealed pathways such as pentose and glucuronic acid interconversion, ascorbic acid and aldonic acid metabolism, the pentose phosphate pathway (PPP), and the Warburg effect. In conclusion, IPC can significantly increase the specific athletic abilities of Taekwondo athletes, with enhancements linked to anaerobic metabolism, PPP utilization, the Warburg effect for energy production, redox system stability, reduced muscle fatigue, and pain alleviation. [ABSTRACT FROM AUTHOR]

This study investigates the impact of quadriceps fatigue on lower limb biomechanics during the landing phase of a single-leg vertical jump (SLJ) in 25 amateur male basketball players from Ningbo University. Fatigue was induced through single-leg knee flexion and extension exercises until task failure. Kinematic and dynamic data were collected pre-fatigue (PRF) and post-fatigue (POF) using the Vicon motion capture system and the AMTI force platform and analyzed using an OpenSim musculoskeletal model. Paired sample t-tests revealed significant changes in knee and hip biomechanics under different fatigue conditions, with knee joint angle (p < 0.001), velocity (p = 0.006), moment (p = 0.006), and power (p = 0.036) showing significant alterations. Hip joint angle (p = 0.002), moment (p = 0.033), and power (p < 0.001) also exhibited significant changes. Muscle activation and joint power were significantly higher in the POF condition, while joint stiffness was lower. These findings suggest that quadriceps fatigue leads to biomechanical adjustments in the knee and hip joints, which may increase the risk of injury despite aiding in landing stability. [ABSTRACT FROM AUTHOR]

Fatigue specifically affects the force production capacity of the working muscle, leading to a decline in athletes' performance. This study investigated the impact of fatigue on ankle flexor muscle activity and ground reaction forces (GRFs) in elite table tennis players, with a focus on the implications for performance and injury risk. Twelve elite male table tennis athletes participated in this study, undergoing a fatigue protocol that simulated intense gameplay conditions. Muscle activity of the soleus (SOL) and gastrocnemius lateralis (GL) muscles, heel height, and GRFs were measured using a combination of wireless electromyography (EMG), motion capture, and force plate systems. Results showed a significant decrease in muscle activity in both legs post-fatigue, with a more pronounced decline in the right leg. This decrease in muscle activity negatively affected ankle joint flexibility, limiting heel lift-off. Interestingly, the maximal anteroposterior GRF generated by the left leg increased in the post-fatigue phase, suggesting the use of compensatory strategies to maintain balance and performance. These findings underscore the importance of managing fatigue, addressing muscle imbalances, and improving ankle flexibility and strength to optimize performance and reduce the risk of injuries. [ABSTRACT FROM AUTHOR]

Objective. The red rhizome of Angiopteris helferiana has been used widely to treat muscle fatigue, bone pain, and skin infection in Nepal. However, scientific evidence for its bioactive compounds and their bioactivities was lacking till January, 2024. Therefore, we investigated to validate and advance the further use and development. Methods. Column chromatography, including MCI gel CHP20P, Sephadex LH‐20, ODS, and Silica gel, was used for the isolation of compounds from 70% methanol extract of A. helferiana rhizomes. The isolated compounds were evaluated for their TLC‐based antioxidant and antibacterial activity against Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli, and Pseudomonas aeruginosa by adopting the agar well diffusion protocol. Furthermore, in silico molecular docking against the penicillin binding protein of E. coli (PBP1b, PBP2, and PBP3 TPd) and ADME toxicity of the isolated compounds was predicted. Results and Discussion. Angiopteroside (1) and osmundalactone (2) were isolated for the first time from the red rhizomes of A. helferiana. The structure of the isolated compounds was elucidated on the basis of spectroscopic (1H‐, 13C‐, and 13C/DEPT‐NMR) and spectrometric (LC MS/ESI and IR) analyses and comparison with reported literature. Both compounds were inactive towards DPPH scavenging activity. Compound 1 showed poor inhibitory activity against E. coli, with inhibition zone range of 2–7 mm. However, both isolated compounds were found to be resistant against S. aureus, K. pneumonia, and P. aeruginosa. Based on in silico molecular docking forecasting, compound 1 revealed the good binding affinity with PBP1b (−6.5 kcal/mol), PBP2 (−5.8 kcal/mol) and PBP3 TPd (−6.1 kcal/mol) compared to positive control meropenem with PBP1b (−6.6 kcal/mol), PBP2 (−6.9 kcal/mol), and PBP3 TPd (−6.6 kcal/mol). Similarly, compound 2 showed weak preference for PBP1b (−4.3 kcal/mol), PBP2 (−4.4 kcal/mol), and PBP TPd (−4.5 kcal/mol). Compounds 1 and 2 were predicted to be safe in terms of hepatotoxicity, cytotoxicity, mutagenicity, and carcinogenicity, with a potential to induce nephrotoxicity similar to that of meropenem. Conclusion. This study successfully isolates two lactones with antibacterial properties and inspires the researcher to further research, development, and formulation. [ABSTRACT FROM AUTHOR]

Above the first lactate threshold, the steady‐state V̇O2${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ is delayed or prevented due to the V̇O2${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ slow component (V̇O2SC${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{SC}}}}$). This phenomenon has been associated with muscle fatigue, but evidence for a causal relationship is equivocal. Moreover, little is known about the contribution of pedalling technique adjustments to V̇O2SC${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{SC}}}}$ during fatiguing cycling exercise. Eleven participants completed constant power trials at 10% above the second lactate threshold. Muscle fatigue was assessed, utilizing femoral nerve stimulation and instrumented pedals, while V̇O2${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$, quadriceps oxygenation, electromyography (EMG) and pedal force components were measured. Correlations between physiological and mechanical variables were estimated at group and individual levels. Group correlations revealed moderate values for V̇O2SC${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{SC}}}}$ with quadriceps twitch force (r = −0.51) and muscle oxygenation (r = −0.52), while weak correlations were observed for EMG amplitude (r = 0.26) and EMG mean power frequency (r = −0.16), and with pedalling mechanical variables such as peak total downstroke force (r = −0.16), minimum total upstroke force (r = −0.16) and upstroke index of effectiveness (r = 0.16). The findings here align with prior literature reporting significant correlations between the magnitude of muscle fatigue and that of V̇O2SC${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{SC}}}}$, although there was large interindividual variability for all the reported correlations. Considering the heterogeneity in the data, it is difficult to determine the relative impact of pedalling technique adjustments on V̇O2SC${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{SC}}}}$ overall, but the present study opens the possibility that in some cases, increases in V̇O2${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}}}$ secondary to technical adjustments may be ‘superimposed’ on the underlying V̇O2SC${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{SC}}}}$. [ABSTRACT FROM AUTHOR]

Featured Application: Importantly, measurements obtained through VOT-NIRS can vary significantly post-exercise, which should be considered by researchers before application. This study evaluated the influence of acute fatigue on heart rate variability (HRV) and muscle oxygen saturation (SmO2) at rest, as well as the reliability of SmO2 data measured using near-infrared spectroscopy (NIRS) during a vascular occlusion test (VOT). Twelve physically active subjects participated. Measurements included perceived muscle soreness using the visual analog scale (VAS pain), HRV parameters, variables of resting SmO2 (desaturation and resaturation), and reoxygenation kinetics (mean response time, MRT) through a VOT-NIRS located in the vastus lateralis (VL). Measurements were taken at three points: 24 h before, before exhaustive exercise, and 30 min after exhaustive exercise. The results indicated that acute fatigue increased resting muscle oxygen consumption in desaturation (+22 SmO2) and resaturation (+18 SmO2), improved MRT (−15 s), and elevated sympathetic nervous system (SNS) activity, as observed in the R-R interval (−262 ms) and SNS index (+0.5). HRV significantly influenced desaturation (r2 = 0.69), resaturation (r2 = 0.60), and MRT (r2 = 0.54). Reliability was established with an ICC of 0.49 and 0.63 for desaturation and resaturation, respectively. Real changes in desaturation and resaturation should be considered ≥ 7% SmO2 at rest and ≥ 11% SmO2 to avoid daily fatigue interference. In conclusion, acute fatigue increases resting SmO2 consumption and is associated with higher SNS activity and increased VAS pain. [ABSTRACT FROM AUTHOR]

This study aimed to develop wearable robotic gloves that can provide comfort to logistics and transportation workers while providing hand assistance and addressing accumulated muscle fatigue caused by repetitive manual handling tasks. Two types of gloves, rivet-type and pouch-type were developed and evaluated using the nine-hole peg test (NHPT) and grip strength tests. Results showed rivet-type gloves had better dexterity, with an 8.14% faster NHPT time, and maintained 85% grip strength compared to 80% for pouch-type gloves, even after fatigue exercises. Wearability tests were conducted by measuring clothing pressure and brainwaves. In contrast to the functional experimental results, the pouch-type gloves exhibited significant decreases in clothing pressure during actuation. According to the difference in brain waves in the frontal lobe region, the beta and gamma waves observed when wearing pouch-type gloves were lower than those of rivet-type gloves, and pouch-type gloves exhibited higher alpha-wave results than rivet-type gloves. These results imply that participants were in a comparatively relaxed state when wearing pouch-type gloves. A wearer's evaluation survey on the overall design, function, comfort, safety, ease of use, usefulness, and use intention was conducted. In summary, the rivet-type gloves exhibited better results in hand performance while the pouch-type gloves showed advantages in wearability, suggesting a tradeoff relationship between force transmission and wearer comfort. The results of this study aimed to improve the work efficiency at logistics and transportation industry sites and help improve the welfare of workers. [ABSTRACT FROM AUTHOR]

Background and Purpose: Developing technology in the field of rehabilitation is vital to accelerate recovery and decrease the side effects of current modalities. Rehabilitation is a challenging science in which the main challenge is not just treating the patient but also to shorten the rehabilitation time and avoid harmful effects. Thus, this review demonstrates the possible design and effects of air therapy as a novel treatment branch besides hydrotherapy, electrotherapy, and manual therapy in the field of rehabilitation. Methods: The search was conducted over clinical trials, literature reviews, and systematic reviews on the possible effects of treatments that may have similar effects to the newly developed air therapy. This search was conducted in the Web of Science, Scopus, EBSCO, and Medline databases. Results: Air therapy could be used to improve the function of mechanoreceptors, improve circulation and microcirculation, decrease pain, the release of trigger points, regain the elasticity of soft tissues, treat acute and chronic inflammations, decrease muscle cramps and spasticity, strengthen muscle, and decrease muscle fatigue and Decreasing muscle fatigue and delayed muscle soreness. Conclusion: Air therapy is a novel treatment modality that can be used effectively in the field of rehabilitation. Air therapy could be a valuable and safe treatment in rehabilitation. [ABSTRACT FROM AUTHOR]

Skeletal muscle fibers need to have mechanisms to decrease energy consumption during intense physical exercise to avoid devastatingly low ATP levels, with the formation of rigor cross bridges and defective ion pumping. These protective mechanisms inevitably lead to declining contractile function in response to intense exercise, characterizing fatigue. Through our work, we have gained insights into cellular and molecular mechanisms underlying the decline in contractile function during acute fatigue. Key mechanistic insights have been gained from studies performed on intact and skinned single muscle fibers and more recently from studies performed and single myosin molecules. Studies on intact single fibers revealed several mechanisms of impaired sarcoplasmic reticulum Ca2+ release and experiments on single myosin molecules provide direct evidence of how putative agents of fatigue impact myosin's ability to generate force and motion. We conclude that changes in metabolites due to an increased dependency on anaerobic metabolism (e.g., accumulation of inorganic phosphate ions and H+) act to directly and indirectly (via decreased Ca2+ activation) inhibit myosin's force and motion-generating capacity. These insights into the acute mechanisms of fatigue may help improve endurance training strategies and reveal potential targets for therapies to attenuate fatigue in chronic diseases. [ABSTRACT FROM AUTHOR]

Background: The incremental exercise test is commonly used to measure maximal oxygen uptake (VO2max), but an additional verification test is often recommended as the "gold standard" to confirm the true VO2max. Therefore, the aim of this study was to compare the peak oxygen uptake (VO2peak) obtained in the ramp incremental exercise test and that in the verification test performed on different days at submaximal intensity. Additionally, we examined the roles of anaerobic performance and respiratory muscle strength. Methods: Sixteen physically active men participated in the study, with an average age of 22.7 ± 2.4 (years), height of 178.0 ± 7.4 (cm), and weight of 77.4 ± 7.3 (kg). They performed the three following tests on a cycle ergometer: the Wingate Anaerobic Test (WAnT), the ramp incremental exercise test (IETRAMP), and the verification test performed at an intensity of 85% (VER85) maximal power, which was obtained during the IETRAMP. Results: No significant difference was observed in the peak oxygen uptake between the IETRAMP and VER85 (p = 0.51). The coefficient of variation was 3.1% and the Bland–Altman analysis showed a high agreement. We found significant correlations between the total work performed in the IETRAMP, the anaerobic peak power (r = 0.52, p ≤ 0.05), and the total work obtained in the WAnT (r = 0.67, p ≤ 0.01). There were no significant differences in post-exercise changes in the strength of the inspiratory and expiratory muscles after the IETRAMP and the VER85. Conclusions: The submaximal intensity verification test performed on different days provided reliable values that confirmed the real VO2max, which was not limited by respiratory muscle fatigue. This verification test may be suggested for participants with a lower anaerobic mechanical performance. [ABSTRACT FROM AUTHOR]

Objective: To observe the effect of functional electrical stimulation (FES) in walking mode on the lower limb muscle contraction pattern of stroke patients. Method: Thirty patients with hemiplegia in the convalescent stage were included. Electrodes were placed on 4 motion points: the hemiplegic tibialis anterior, quadriceps femoris, gastrocnemius and hamstring muscles respectively. The patients walked with FES machine and received electrical stimulation. The surface electromyogram (sEMG) signals were collected on 4 different time: pre-treatment, treatment at 5 min, 10 min, and 15 min respectively. Median frequency (MDF) of electromyography reflected the current trend of muscle fatigue, and the co-contraction ratio (CI) showed for contraction patterns of antagonistic muscles in extension of knee and ankle-back, through analyzing the sEMG signals changes of 4 motion points muscle in active contraction. Rated perceived fatigue Exertion(RPE) was used to evaluate the patients’fatigue feeling at 4 time points. Result: The CI of the gastrocnemius muscle during ankle dorsiflexsion and hamstring muscles during knee extension were significantly reduced in electrical stimulation group at 5min and 10min after walking than in the pre-treatment and pseudo-stimulation control groups (P<0.05); however, the CI of antagonist muscles increased after 15min of the treatment, especially the CI of the hamstring muscles during knee extension was not significantly different from that before treatment (P＞0.05). The MDF values of tibialis anterior, gastrocnemius, rectus femoris and hamstring muscles in the electrical stimulation group were significantly lower at 5 min, 10 min and 15 min of the treatment compare with the pre-treatment and control group (P<0.05). The MDF value was lower with longer stimulate time, while the control group was significantly lower at 15-min of pesudo-stimulation than the level before treatment (P<0.05). No patients reported fatigue before and after walking with wearing FES machine for 5 min, but did after 10 min and 15 min in both groups . The percentages of the patents who reported fatigue in electrical stimulation group at 10min and 15min were higher than that of the control group(40%, 80% vs 20%, 40%). Conclusion: Functional electrical stimulation for 5—10min can significantly improve the contraction pattern of lower limbs muscle, but the declining muscular coordination when knee extension and ankle dorsiflexsion after 15min stimulation, especially rectus femoris and hamstrings. It is recommended that the walking duration with electrical stimulation machine should not exceed 15 min, in order to avoid the aggravation of fatigue affecting the therapeutic effect of FES treatment. [ABSTRACT FROM AUTHOR]

Background: In general, it has been suggested that females are more fatigue-resistant than males, with the magnitude of difference being most pronounced during low-intensity sustained contractions. However, the mechanisms for the apparent sex difference have not yet been fully elucidated in the literature. This study aimed to examine sex-related differences in fatigability and patterns of neuromuscular responses for surface electromyographic (sEMG) and mechanomyographic (sMMG) amplitude and frequency (MPF) characteristics during a sustained submaximal bilateral, isometric leg extension muscle action. Methods: A sample of 20 young recreationally active males and females with previous resistance training experience performed a sustained, submaximal, bilateral isometric leg extension until task failure. Time-to-task failure was compared using a nonparametric bootstrap of the 95% confidence interval for the mean difference between males and females. Additionally, patterns of response for sEMG and sMMG amplitude and MPF of the dominant limb were examined using linear mixed effect models. Results: There were no differences in time-to-task failure between males and females. Additionally, neuromuscular responses revealed similar patterns of responses between males and females. Interestingly, sEMG amplitude and sMMG amplitude and MPF all revealed non-linear responses, while sEMG MPF demonstrated linear responses. Conclusion: These data revealed that time-to-task failure was not different between males and females during sustained submaximal bilateral, isometric leg extension. Interestingly, the parallel, non-linear, increases in sEMG and sMMG amplitude may indicate fatigue induced increases in motor unit recruitment, while the parallel decreases in sMMG MPF may be explained by the intrinsic properties of later recruited motor units, which may have inherently lower firing rates than those recruited earlier. [ABSTRACT FROM AUTHOR]

We examined the sensitivity and time‐course of recovery of neuromuscular and perceptual player monitoring measures to U‐18 English Premier League academy football match play. Eighteen players performed maximal posterior chain, hip adductor and abductor isometric strength tests, countermovement jumps (CMJ) and provided self‐report wellbeing scores around eight competitive league home games: 1 day before (MD‐1), pre‐match (MD‐PRE), post‐match (MD‐POST) and two (MD+2) and three (MD+3) days post‐match. A permutational multivariate analysis of variance and post hoc univariate analyses of variance were used to examine match‐induced responses to monitoring variables. Between MD‐1 and MD‐POST, we observed small to moderate reductions to the adductor and abductor peak force and maximal impulse and IPCS peak force; small reductions to CMJ jump height (JH) (flight time), eccentric peak force and eccentric deceleration rate of force development and moderate to large reductions to perceived fatigue, muscle soreness and mood. No match‐induced changes were observed for CMJ flight time: contraction time or eccentric duration. Posterior chain, abductor, CMJ and self‐report measures normalised by MD+3 but adductor peak force remained compromised at MD+3 (ES = small). Posterior chain, adductor and abductor peak isometric force and maximal impulse; CMJ JH, eccentric peak force and eccentric deceleration rate of force development and perceived fatigue, muscle soreness and mood are sensitive to match‐induced fatigue. Since adductor peak force remained compromised at MD+3, it is apparent that players might not achieve complete neuromuscular recovery within 3 days of match play, and that the adductor muscle group might be particularly vulnerable to match‐induced fatigue. Highlights: U‐18 English Premier League (EPL) academy football match play induced acute reductions to countermovement jump (jump height [flight time], eccentric peak force and eccentric deceleration rate of force development); isometric strength (abductor, adductor and posterior chain peak force and abductor and adductor maximal impulse) and athlete self‐report (perceived fatigue, muscle soreness and mood) measures.Match‐induced changes to countermovement jump, abductor, posterior chain and self‐report measures typically normalised between MD+2 and MD+3 but adductor peak force remained compromised at MD+3.No meaningful match‐induced changes were observed to widely used countermovement jump movement strategy measures (i.e., flight time: contraction time ratio or eccentric duration).U‐18 EPL academy football players might not achieve complete neuromuscular recovery by MD+3. The adductor muscle group might be particularly susceptible to match‐induced fatigue. [ABSTRACT FROM AUTHOR]