Neuromuscular fatigability is not affected by the contraction pattern of exercises with a similar mean torque

PURPOSE

Neuromuscular fatigability is task-dependent, but the influence of the contraction pattern on neuromuscular fatigability is largely unknown. Therefore, the present study aims to investigate if neuromuscular fatigability is affected by the contraction pattern of exhausting isometric exercises.

METHODS

Thirteen participants sustained a plantar flexors MVC for 1 min (MVC1-MIN) before and after exhausting exercises designed to produce a similar mean torque (30% MVC), and following a 10-min rest period. Exercises consisted of intermittent (INT), continuous (CON) or variable (continuous contraction alternating between moderate and low intensity, VAR) contractions performed until task failure.

RESULTS

The INT resulted in greater exercise duration and torque-time integral than CON and VAR. MVC similarly decreased after all exercises due to neural and muscular impairments. The torque loss during the MVC1-MIN increased after all exercises to a similar extent, mainly because of neural alterations. Contrary to MVC, the torque loss during the MVC1-MIN returned to baseline value after the recovery period.

CONCLUSION

INT, CON and VAR exercises, performed with identical mean torque and until exhaustion, led to a similar neuromuscular fatigability. When the mean torque is matched among exercises, the contraction pattern does not influence the extent of neuromuscular fatigability, assessed through the maximal torque production and sustainability. The present findings are crucial to consider for the management of neuromuscular fatigability in physical conditioning in both athletes and patients.

Physiological and Biomechanical Responses Induced by a Continuous Test and an Intermittent Test in Middle-Distance Runners

PURPOSE

This study aimed to examine middle-distance runners' acute physiological and biomechanical responses to 2 maximal aerobic speed tests: an intermittent test (5 × 1 mintest) and a continuous test (University of Montreal Track Test [UM-TT]).

METHODS

Twenty trained male middle-distance runners completed the UM-TT and 5 × 1 mintest on separate days. The rating of perceived exertion, peak heart rate, and maximal aerobic speed of both tests (VUM-TT and V5 ×1m) were analyzed. Heart-rate variability (time and frequency domain) and spatiotemporal parameters were measured preexercise and postexercise at 5, 30, and 60 minutes.

RESULTS

No differences were found between VUM-TT and V5×1m (18.4 [1.0] vs 18.5 [0.9] km·h-1, r = .88, P = .14). Peak heart rate was similar between tests (UM-TT: 188.6 [4] beats·min-1 vs 5 × 1 mintest: 189 [2] beats·min-1, r = .63, P = .23). Rating of perceived exertion was higher in UM-TT (UM-TT: 8.1 [0.5] vs 5 × 1 mintest: 7.6 [0.7], r = .47, P = .009). For both tests, heart-rate-variability parameters indicated higher sympathetic/lower parasympathetic activity compared with baseline at all time points (P < .001), without differences between tests. Stride frequency and duty factor increased postexercise (P < .05), with no changes in contact time and stride time (P > .05), without differences between the 2 tests.

CONCLUSIONS

Both tests significantly changed heart-rate variability and biomechanical parameters, with no differences between the tests. As 5 × 1 mintest was perceived as less demanding, it may be a less taxing alternative for assessing maximal aerobic speed in middle-distance runners.

The effect of radiofrequency therapy for nasal valve collapse in endurance athletes: A STROBE analysis

OBJECTIVE

Conducting a prospective pilot study to investigate the effect of temperature-controlled radiofrequency treatment of the nasal valve in endurance athletes with internal nasal valve collapse.

MATERIAL AND METHODS

Twenty-five endurance athletes with nasal valve collapse were recruited from 2018 to 2020. Eight of the 25 patients dropped out of the study due to different reasons (injured due to non-nasal causes before postoperative measurement, refusal of surgery in the short term, termination due to corona pandemic), so that 17 study participants completed the study. We investigated NOSE questionnaire and rhinomanometry before and after radiofrequency treatment of the internal nasal valve (Vivaer radiofrequency probe). In addition, an exhaustive treadmill test before and after radiofrequency treatment was performed. The collected measurements were registered and compared with paired t-test. A Cohen's dz was performed for significant results. The normal distribution was confirmed by using the Kolmogorov-Smirnov test and Q-Q plots.

RESULTS

There was a significant improvement in the NOSE score (P<0.001, Cohen's dz=1.03) and no serious side effects. No significant differences were seen before and after the treatment in rhinomanometry and spiroergometry.

CONCLUSION

Due to the low side effects and the subjective improvement in nasal breathing according to the NOSE score, the technique could perhaps represent a promising non-invasive therapy for improving nasal breathing in endurance athletes. However, no significant improvement was observed in the objective parameters. Larger study cohorts are required to investigate the effect in more detail.

Characteristics, Antioxidant Activity Stability, and Anti-Fatigue Activity of Hydrolysates from Cucumaria frondosa Tentacles

This study aimed to assess the impact of alcalase, trypsin, flavourzyme, and neutrase on the characteristics, antioxidant activity stability, and anti-fatigue activity of hydrolysates derived from Cucumaria frondosa tentacles (CFTHs). The results demonstrate that favourzyme hydrolysates exhibited the highest degree of hydrolysis (DH). Zeta potential and particle size measurements indicated that hydrolyzed peptides treated with favourzyme appeared aggregated and exhibited larger particle sizes. The antioxidant properties of CFTHs demonstrated good thermal stability, pH stability, and enhanced simulated gastrointestinal digestive stability. The anti-fatigue activity of CFTHs was examined using an acute exercise fatigue model. The results indicate that CFTHs extended the exhaustive swimming time of mice to 17.81 min. Additionally, CFTHs significantly elevated (p < 0.01) blood glucose (Glu) and liver glycogen (LG) levels, while also decreasing (p < 0.05) the concentrations of metabolites such as lactic acid (LA), urea nitrogen (BUN), creatine kinase (CK), lactate dehydrogenase (LDH), and ammonia (NH3). This reduction contributed to the alleviation of fatigue in the body. Furthermore, the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were significantly increased (p < 0.05), which aided in mitigating oxidative damage induced by strenuous exercise. These findings strongly support the potential utilization of CFTHs in food products as natural antioxidant and anti-fatigue alternatives.

The effect of transcranial pulse current stimulation on the accumulation of exercise-induced fatigue in college students after moderate intensity exercise evidence from central and peripheral sources

Objective

To investigate the intervention effect of cranial pulse current stimulator (tPCS) on fatigue accumulation after moderate-intensity exercise by using blood analysis and functional near-infrared spectroscopy, and to analyze the type and magnitude of the fatigue effect of tPCS on fatigue in combination with behavioral performance.

Methods

Ninety healthy college students were randomly and equally divided into an experimental group (Group A) and a control group (Group B), and both groups underwent moderate-intensity training for 7 days. Before and after the experiment, all subjects received physiological, biochemical, behavioral, and subjective fatigue indexes, followed by exercise training, and each day of exercise training was followed by tPCS intervention (stimulus intensity of 1.5 mA, stimulus duration of 20 min) and subjective fatigue scale (RPE) test.

Results

① After the tPCS intervention, the daily RPE scores of group A were smaller than those of group B; ② The values of the indexes oxygenated hemoglobin concentration (Oxy-Hb), deoxyhemoglobin concentration (HHb), testosterone (T), and testosterone-to-cortisol ratio (T/C) of group A did not differ significantly from those of the pre-intervention period, and the values of all the indexes of group B were significantly different from those of the pre-intervention period. ③ After tPCS intervention, the values of Oxy-Hb, T, T/C, and on-attention decreased in Groups A and B, with Oxy-Hb decreasing the most; the values of HHb, total hemoglobin concentration (HbTot), hemoglobin concentration difference (HbDiff), cortisol (C), creatine kinase (CK), and reaction time (RT) increased, with the greatest increase in HbDiff; and the Group A The magnitude of change of each index was smaller than that of Group B. After tPCS intervention, the contribution of central fatigue to the effect of reaction time science was greater than that of peripheral fatigue.

Conclusion

① tPCS can delay the development of central fatigue and peripheral fatigue. ② The effect of tPCS on central fatigue is greater than on peripheral fatigue. ③ The effect of tPCS on reaction timing is mainly realized by changing the state of central fatigue.

Fractal correlation properties of heart rate variability and respiratory frequency as measures of endurance exercise durability

PURPOSE

Field-based measures of durability (exercise-related physiologic deterioration over time) for assessing athletic fitness often rely on changes in maximal power profiles or heart rate (HR) drift. This study aimed to determine whether an index of HR variability based on the short-term exponent of Detrended Fluctuation Analysis (DFA a1) along with respiratory frequency (fB) could demonstrate changes in durability during a Time to Task Failure (TTF) Trial.

METHODS

Ten participants performed a cycling TTF at an intensity of 95% of the respiratory compensation point (RCP) on two occasions, Control and a "Reward" where a monetary incentive was offered when task failure was signaled. Metabolic responses including oxygen uptake (V ˙ O 2 ), lactate and glucose along with HR, DFA a1 and fB were measured and compared over each quarter of the TTF up to the time of signaling (Q1, Q2, Q3, and Q4).

RESULTS

The elapsed time of TTF sessions was statistically similar (p = 0.54). After initial equilibration, metabolic responses remained largely stable over Q2-Q4. HR, DFA a1 and fB displayed drift over Q2-Q4 with significant ANOVA. Repeatability of quarterly HR, DFA a1, and fB between Control and Reward sessions was high with ICC between 0.73 and 0.94, Pearson's r was between 0.83 and 0.98 with no difference in mean values by paired t testing.

CONCLUSION

HR, fB and DFA a1 are useful metrics representing alteration in physiologic characteristics demonstrating durability loss during an endurance exercise session. These measures were repeatable across sessions and have the potential to be monitored retrospectively or in real time in the field with low-cost consumer equipment.

Mechanical power distribution of the lower limbs changed during intermittent 300 countermovement jumps

PURPOSE

The aim of this study was to investigate the effect of 300 intermittent countermovement jumps (CMJs) on the mechanical power distribution at the joints of the lower limbs and the influence of the upper body to explain vertical jump performance.

METHODS

Fifteen male sport students (age 24.5 ± 2.3 years; body height 1.85 ± 0.06 m; body mass 84.8 ± 8.5 kg) performed a set of intermittent 300 CMJs at maximal effort. An inverse-dynamic approach was used to calculate the mechanical power at the hip, knee, and ankle joint for each jump.

RESULTS

Jump height and mechanical power in the knee and ankle joints decreased significantly (p < .010), while remained the same in the hip joint. In contrast, a significant increased vertical velocity was observed for the upper body segment. In addition, a significant higher angular momentum at the center of mass was detected during the braking and propulsion phase.

CONCLUSION

The findings highlight a fatigue-related decrease in lower limb power, particularly in the knee and ankle joints, which changed the mechanical power distribution at the joints of the lower limbs. The trunk extensor muscles were probably able to counteract the fatigue-related decrease in lower limb power by increased vertical velocity of the upper body segment and higher angular momentum at the center of mass during the braking and propulsion phase. Accordingly, the most effective way to maintain jumping performance in fatigued state would be to improve the fatigue resistance of the knee extensors, ankle plantar flexors, and trunk extensor muscles.

The effect of acute branched-chain amino acids ingestion on rate of force development in different time intervals: a controlled crossover study

Background

Branched-chain amino acids (BCAAs) are widely used as sports nutrition supplements. However, their impact on the rate of force development (RFD), an indicator of explosive muscle strength, has not yet been validated. This study aimed to assess the impact of BCAA supplementation on the RFD in college basketball players during simulated games.

Methods

This study employed a randomized, controlled crossover, double-blind design. Participants received either BCAAs (0.17 g/kg combined with 0.17 g/kg isocaloric glucose) or a placebo (0.34 g/kg isocaloric glucose) orally 30 min before beginning the exercise protocol. The RFD was quantified using the isometric mid-thigh pull (IMTP) test. Additional outcome measures, including strength and jump tests, agility and sprinting tests, and physiological responses, were also assessed. A two-way repeated measures ANOVA was employed to evaluate the impact of supplements (BCAAs and placebo) on RFD and other related outcome measures.

Results

Analysis of the 50 ms RFD demonstrated significant main effects of BCAA supplementation (p = 0.003). The BCAAs group consistently exhibited higher levels of 50 ms RFD compared to the placebo group across rounds 1 to 4. For example, in round 1, the 50 ms RFD was 3702.3 ± 1223.2 N/S in the BCAAs group versus 2931.3 ± 888.8 N/S in the placebo group (p = 0.045). Although no significant between-group differences were observed for the 100, 150, 200, and 250 ms RFD measurements, the BCAAs group consistently showed superior values across all time points. The results of other outcome indicators also suggested that supplementation with BCAAs was indeed effective.

Conclusion

The results indicate that BCAA supplementation can enhance RFD in basketball players, particularly at the 50 ms RFD. Our research design provides reliable insights into the effects of BCAAs on athletic performance. Further studies of similar design with larger sample sizes are necessary to confirm and extend these findings.

Clinical trial registration

Chinese Clinical Trial Registry, ChiCTR2400091314 (https://www.chictr.org.cn).

Effects of Maca (Lepidium meyenii Walp.) on Physical Performance in Animals and Humans: A Systematic Review and Meta-Analysis

BACKGROUND

Lepidium meyenii Walp. (LmW), known as maca, has been shown to increase physical performance. However, the effect size (ES) of LmW on the different manifestations of physical performance has not yet been described.

OBJECTIVES

To examine and qualitatively describe the studies published up to 2024 that employed LmW supplementation to increase physical performance in animal and human experimentation. In addition, the ES associated with the different interventions was calculated.

METHODS

The research followed PRISMA® guidelines for systematic reviews and meta-analyses, using Web of Science, Scopus, SPORTDiscus, PubMed, and MEDLINE databases until 2024. Randomized controlled studies with a pre- and post-test design, conducted both in vitro and in vivo in animals and humans, were included. Methodological quality assessment was performed using the CAMARADES tool for animal studies and the Newcastle Ottawa Scale for human studies. The main variables were the forced swimming test (FST), the rota-rod test (RRT), the grip strength test (GST), blood lactic acid (BLA), and lactic acid (LA). The analysis was conducted with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI).

RESULTS

Twenty-one studies were included in the systematic review and sixteen in the meta-analysis. They revealed a large effect for all outcomes (SMD: FST = 2.26, RRT = 6.26, GST = 5.23, LA = -1.01, and BLA = -1.70).

CONCLUSIONS

The phytochemical compounds of LmW, mainly macamides, increase physical performance, showing a greater effect at higher doses (dose-response effect).

Plant polysaccharides and antioxidant benefits for exercise performance and gut health: from molecular pathways to clinic

In the last three decades, our understanding of how exercise induces oxidative stress has significantly advanced. Plant polysaccharides, such as dietary fibers and resistant starches, have been shown to enhance exercise performance by improving energy metabolism, reducing fatigue, increasing strength and stamina, mitigating oxidative stress post-exercise, facilitating muscle recovery, and aiding in detoxification. Moreover, antioxidants found in plant-based foods play a crucial role in protecting the body against oxidative stress induced by intense physical activity. By scavenging free radicals and reducing oxidative damage, antioxidants can improve exercise endurance, enhance recovery, and support immune function. Furthermore, the interaction between plant polysaccharides and antioxidants in the gut microbiota can lead to synergistic effects on overall health and performance. This review provides a comprehensive overview of the current research on plant polysaccharides and antioxidants in relation to exercise performance and gut health.

Quantifying Active and Passive Stiffness in Plantar Flexor Muscles Following Intermittent Maximal Isometric Contractions Using Shear Wave Elastography

OBJECTIVE

This study aimed: (i) to investigate the impact of fatigue, triggered by maximal isometric contraction exercises, on the active and passive stiffness of plantar flexors (PF), and (ii) to examine the relationship between changes in mechanical parameters and neuromuscular alterations after fatigue.

METHODS

A healthy cohort (n = 12; age = 27.3 ± 5.5 y; BMI = 24.4 ± 2.35 kg/m²) was instructed to perform 60 isometric contractions, each lasting 4 s with a 1-s rest interval, using an ergometer. Several measures were taken before and after the fatigue protocol. First, the stiffness of the PF-tendon complex (PFC) was quantified during passive ankle mobilization both during and after the fatigue protocol using the ergometer. Additionally, from shear wave elastography, the active and passive stiffness of the gastrocnemius medialis (GM) were measured during passive ankle mobilization and isometric maximal voluntary contraction (MVC), respectively. Finally, the peak torque and the rate of torque development (RFD) of PF were assessed during the MVC using the ergometer. Ankle muscle activities (surface electromyograph [SEMG]) were recorded during all evaluations using electromyography.

RESULTS

After the fatigue protocol, the results revealed a decline in active stiffness, peak torque of PF, RFD and SEMG activity of the GM (p < 0.001). Furthermore, significant correlation was identified between the decrease of the peak torque of PF and the active stiffness of the GM (r = 0.6; p < 0.05). A decrease in the PFC stiffness (p < 0.001) and a decrease in the shear modulus of the GM at 20° (p < 0.001) were also observed.

CONCLUSION

Isometric fatiguing exercises modify the mechanical properties of both the contractile and elastic components. Notably, decreases in both passive and active stiffness may be critical for athletes, as these changes could potentially increase the risk of injury.

The Effects of Competition on Exercise Intensity and the User Experience of Exercise during Virtual Reality Bicycling for Young Adults

BACKGROUND

Regular moderate-vigorous intensity exercise is recommended for adults as it can improve longevity and reduce health risks associated with a sedentary lifestyle. However, there are barriers to achieving intense exercise that may be addressed using virtual reality (VR) as a tool to promote exercise intensity and adherence, particularly through visual feedback and competition. The purpose of this work is to compare visual feedback and competition within fully immersive VR to enhance exercise intensity and user experience of exercise for young adults; and to describe and compare visual attention during each of the conditions.

METHODS

Young adults (21-34 years old) bicycled in three 5 min VR conditions (visual feedback, self-competition, and competition against others). Exercise intensity (cycling cadence and % of maximum heart rate) and visual attention (derived from a wearable eye tracking sensor) were measured continuously. User experience was measured by an intrinsic motivation questionnaire, perceived effort, and participant preference. A repeated-measures ANOVA with paired t-test post hoc tests was conducted to detect differences between conditions.

RESULTS

Participants exercised at a higher intensity and had higher intrinsic motivation in the two competitive conditions compared to visual feedback. Further, participants preferred the competitive conditions and only reached a vigorous exercise intensity during self-competition. Visual exploration was higher in visual feedback compared to self-competition.

CONCLUSIONS

For young adults bicycling in VR, competition promoted higher exercise intensity and motivation compared to visual feedback.

Differences in motivational dynamics between experienced cyclists and untrained participants during an incremental endurance exercise task

PURPOSE

The conflict between the desire to reduce effort during exercise and the performance goal of the exercise task contributes to explaining endurance exercise performance. However, whether the trajectories of these two motivational responses systematically differ across individuals with different characteristics is poorly understood. The present study examined whether changes in desire to reduce effort and performance goal value across moderate, heavy, and severe exercise intensity domains differed between cyclists and untrained, but active participants.

METHODS

Fifty participants (14 cyclists and 36 untrained) completed an incremental step test on a cycle ergometer, in which work rate was increased by 25 W every 4 min until voluntary exhaustion. Desire to reduce effort, performance goal value, and blood lactate concentration (for determination of exercise intensity domains) were measured every 4 min and the data were analysed using multilevel modelling.

RESULTS

Desire to reduce effort increased quicker for untrained participants in the moderate exercise intensity domain (b = 1.66, p < .001) and across the whole trial (b = 1.64, p < .001), compared to cyclists (b = .69, and b = 1.14, respectively, both p < .001). Untrained participants reported similar performance goal value at the beginning of the trial (b = 16.02, p < .001), compared to cyclists (b = 17.25, p < .001). Beyond moderate intensities, the performance goal value decreased significantly for the untrained participants (b = -.70, p < .001) but significantly increased for cyclists (b = .45, p = .01). This pattern was also observed when focusing solely on the severe intensity domain (cyclists: b = .90, p < .001; untrained: b = -.84, p < .001).

CONCLUSION

There are distinct differences in the desire to reduce effort and performance goal value between cyclists and untrained athletes. Identifying these systematic differences enhances the credibility of the desire-goal conflict framework in explaining endurance performance and provides insight into the type and timing of interventions that might be successful in improving performance.

The Impact of Physiological and Psychological Fatigue on Work Efficiency: A Case Study of Parcel Sorting Work

The popularity of online shopping in China has increased significantly, creating new development opportunities for the express delivery industry. However, the rapid expansion of the express industry has also created challenges in the parcel sorting process. The demanding nature of parcel sorting work, which is characterized by intense and prolonged repetitive tasks, makes individuals particularly vulnerable to the effects of fatigue. Fatigue is a complex condition that encompasses both physiological and psychological exhaustion. It often results in reduced energy levels and diminished functionality, significantly impacting an individual's performance at work and their overall well-being. This study aimed to investigate how physiological and psychological fatigue affects sorting efficiency and to identify appropriate rest periods that will allow employees to maintain their performance levels. The research involved fifteen participants who took part in a 60 min continuous sorting experiment and a similar experiment with scheduled breaks. During both trials, we collected data on participants' electromyography (EMG) and electrodermal activity (EDA), as well as subjective fatigue ratings (RPE). Signal features such as the median frequency (MF) of EMG and the skin conductance level (SCL) were analyzed to assess physiological and psychological fatigue, respectively. The results show that physiological fatigue mainly affects sorting efficiency in the first 30 min, while psychological fatigue becomes more influential in the following half-hour period. In addition, subjective fatigue levels during the first 30 min are primarily determined by psychological factors, while beyond that point, both physiological and psychological fatigue contribute to subjective fatigue. Rest periods of 415-460 s, based on EDA recovery times, effectively support sorting efficiency and participants' recovery. This study highlights the complex ways in which fatigue affects parcel sorting performance and provides valuable theoretical and practical insights for establishing labor quotas and optimizing work schedules in the parcel sorting industry.

Effect of Lower Limb Muscle Fatigue on Dynamic Balance Performance in Healthy Young Adults: Role of Arm Movement

There is evidence that balance performance deteriorates due to exercise-induced muscle fatigue. However, it is unknown if free arm movement during balance testing can compensate for, or restricted arm movement can amplify these performance degradations. Thus, the objective of this study was to compare the effects of free versus restricted arm movement on balance performance under non-fatigued and fatigued conditions. Fifty-two healthy participants (men=31, women=21; age=22.6±1.6 years) were assessed for their dynamic balance (reach distances for the Y Balance Test - Lower Quarter) under non-fatigued and fatigued (repetitive vertical bipedal box jumps until failure) conditions using two different arm positions: free (move the arms freely) and restricted (keep the arms akimbo) arm movement. Restriction of arm movement (all p< 0.001; 0.48≤ η p 2 ≤0.79) and application of fatigue ( p≤ 0.003; 0.16≤ η p 2 ≤0.28) independently, but not the interaction between the two (except for the posteromedial reach direction: p= 0.046; η p 2 =0.08) , resulted in significantly deteriorated lower limb reach distances. These findings suggest that free arm movement and thus the use of an 'upper body strategy' has no compensatory effect on muscle fatigue-induced balance deteriorations.

Periodontal disease and sports performance: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to assess the association between athletic performance and periodontal disease (PD). Observational studies published up to April 2022 were searched in online databases (PubMed, Scopus, Web of Science, The Cochrane Library, LILACS, OpenGrey, and Google Scholar). PECO statement focused on studies with professional athletes (Participants) with PD (Exposition) compared to those with healthy periodontium (Comparison) and its effects on sports performance (outcome). Searches were conducted according to the PRISMA guidelines (registration protocol: 10.17605/OSF.IO/7ADH6) and risk of bias evaluation according to the Joanna Briggs Institute checklist. A total of 793 references were retrieved, of which eight were considered eligible. Two studies did not show an association between clinical PD parameters and performance. A meta-analysis with 396 participants suggested a relationship between PD and self-reported reduction in sports performance (odds ratio [OR] = 1.55; 95% confidence interval [CI] 1.04-2.31; p = 0.03; I2 = 0%) with moderate quality of evidence accordingly GRADE analysis. Despite the differences in performance evaluations between studies, PD was associated with reduced self-reported sports performance. Additional studies assessing confounding factors and objective assessment of PD and performance are needed to clarify the real effect of both conditions.

Evaluation of sweat-based biomarkers using wearable biosensors for monitoring stress and fatigue: a systematic review

Objectives. This systematic review aims to report the evaluation of wearable biosensors for the real-time measurement of stress and fatigue using sweat biomarkers. Methods. A thorough search of the literature was carried out in databases such as PubMed, Web of Science and IEEE. A three-step approach for selecting research articles was developed and implemented. Results. Based on a systematic search, a total of 17 articles were included in this review. Lactate, cortisol, glucose and electrolytes were identified as sweat biomarkers. Sweat-based biomarkers are frequently monitored in real time using potentiometric and amperometric biosensors. Wearable biosensors such as an epidermal patch or a sweatband have been widely validated in scientific literature. Conclusions. Sweat is an important biofluid for monitoring general health, including stress and fatigue. It is becoming increasingly common to use biosensors that can measure a wide range of sweat biomarkers to detect fatigue during high-intensity work. Even though wearable biosensors have been validated for monitoring various sweat biomarkers, such biomarkers can only be used to assess stress and fatigue indirectly. In general, this study may serve as a driving force for academics and practitioners to broaden the use of wearable biosensors for the real-time assessment of stress and fatigue.

Threshold effect of physical exercise on its association to diabetes mellitus in short sleep population: evidence from a nationwide study

BACKGROUND

The prevalence of diabetes mellitus (DM) is a significant public health concern, especially among individuals with short sleep duration. Understanding the relationship between physical exercise and DM in this population is crucial for developing effective prevention strategies. However, the presence of a potential threshold effect of exercise on DM risk remains unclear.

METHODS

Using data from the National Health and Nutrition Examination Survey (NHANES) spanning from 2007 to 2018, this population-based study investigated the association between physical exercise and DM in individuals with short sleep duration (no more than 7 hours per night). Weighted logistic regression analyses were conducted, adjusting for demographic and lifestyle factors. Additionally, a two-piecewise linear regression model was employed to identify any threshold effect of exercise on DM risk.

RESULTS

This study included 15,092 participants identified with short sleep duration. Demographic characteristics stratified by DM status indicate higher prevalence among certain groups, such as middle-aged and older adults, males, and non-Hispanic Whites. The analysis revealed an inverse association between exercise levels and DM prevalence among the short sleep population. In the fully adjusted model, individuals engaging in sufficient exercise (> 600 MET-minutes/week) exhibited significantly reduced odds of developing DM [OR (95% CI): 0.624(0.527,0.738), p < 0.001]. Furthermore, the segmented regression model identified an inflection point at 2000 MET-minutes/week, below which a significant correlation between exercise and DM was observed.

CONCLUSIONS

This study provides evidence of a threshold effect of physical exercise on its association with DM in individuals with short sleep duration. Tailored exercise interventions targeting this population may help mitigate DM risk and improve overall health outcomes. Further research is warranted to validate these findings and explore optimal exercise thresholds for DM prevention strategies.

Predicting the occurrence of minor adverse events in cardiac rehabilitation using physical variables

The safety of exercise practice by individuals with cardiovascular disease is due to a good clinical evaluation to identify patients with a higher risk of adverse events, thus the study of simple variables capable of predicting the rate of events during exercise is relevant and may provide better screening tools to be applied in the clinical practice. The study aimed to evaluate if clinical and physical parameters can predict the rate of adverse events during exercise-based cardiac rehabilitation. This was a cohort study that followed 73 patients during 24 sessions of exercise. Were registered 217 simple adverse events, at a rate of 2.5 events per hour of exercise. We found that higher adiposity, worse pulmonary function, lower functional capacity, and reduced heart rate variability were significant and acceptable predictors of adverse events during exercise, according to the ROC curve analysis. We state that these simple physical parameters may be useful for cardiac risk stratification in cardiac rehabilitation programs with low resources, contributing to its safety.

Substrate utilization and durability during prolonged intermittent exercise in elite road cyclists

PURPOSE

This study investigated the effects of prolonged intermittent cycling exercise on peak power output (PPO) and 6-min time-trial (6 min-TT) performance in elite and professional road cyclists. Moreover, the study aimed to determine whether changes in performance in the fatigued state could be predicted from substrate utilization during exercise and laboratory measures obtained in a fresh state.

METHODS

Twelve cyclists (age: 23 years [21;25]; body mass: 71.5 kg [66.7;76.8]; height: 181 cm [178;185]; V ˙ O2peak: 73.6 ml kg-1 min-1 [71.2;76.0]) completed a graded submaximal cycling test to determine lactate threshold (LT1), gross efficiency (GE), and maximal fat oxidation (MFO) as well as power output during a maximal 6 min-TT (MPO6 min) in a fresh condition. On a separate day, the cyclists completed a 4-h intermittent cycling protocol with a high CHO intake (100 g h-1). Substrate utilization and PPO was measured hourly during the protocol, which was followed by another 6 min-TT.

RESULTS

MPO6 min and PPO was reduced by 10% [4;15] and 6% [0;6], respectively, after the cycling protocol. These reductions were accompanied by reductions in the anaerobic energy contribution and V ˙ O2peak, whereas the average V ˙ O2 during the 6 min-TT was unchanged. Correlation analyses showed no strong associations between reductions in MPO6 min and PPO and laboratory measures (i.e., LT1, GE, MFO, V ˙ O2peak) obtained in the fresh condition. Additionally, fat oxidation rates during the cycling protocol were not related to changes in neither PPO nor MPO6 min.

CONCLUSION

PPO and MPO6 min were reduced following prolonged intermittent cycling, but the magnitude of these reductions could not be predicted from laboratory measures obtained in the fresh condition.

Characteristics and Frequency of Physical Activity and Exercise-Related Side Effects in People Receiving Peritoneal Dialysis

OBJECTIVE

People receiving peritoneal dialysis may receive health benefits from physical activity or exercise. However, on-going uncertainty and fear regarding safety may result in this population missing out on the health benefits of participation. The aim of this study was to explore the characteristics and frequency of physical activity and/or exercise-related side effects (e.g., symptoms such as pain or shortness of breath) and negative health events (e.g., stroke or hyper/hypoglycemia) experienced by people receiving peritoneal dialysis.

METHODS

An international online survey involving adults receiving peritoneal dialysis was conducted with questions related to nature, occurrence, and impact of side effects and/or negative health events experienced during or soon after participation in physical activity or exercise.

RESULTS

Fifty-two people completed the survey reporting 151 side effects that were related to physical activity and exercise and 67 that were possibly related. Fatigue (58% of respondents), muscle/joint soreness or pain (54%), and dizziness (43%) were the most frequently reported side-effect types. The majority occurred occasionally (58% of all side effects), if not rarely (24%) and participation in on-going physical activity or exercise was typically prevented only occasionally (39%) or not at all (31%). Side effects were mainly self-managed (54% of all side effects) or did not require treatment (19%) and had low (38%) or no effect (30%) on ability to do daily activities.

CONCLUSIONS

People receiving peritoneal dialysis generally experience side effects that can be considered a normal response to physical activity or exercise engagement. Furthermore, the risk of serious or peritoneal dialysis-specific side effects as a result of physical activity or exercise appears to be low. The results add to the emerging evidence suggesting physical activity and exercise appear to be safe for people receiving peritoneal dialysis.

Relationship Between Training Load, Neuromuscular Fatigue, and Daily Well-Being in Elite Young Wrestlers

Purpose: This study investigated acute workload (wAW), chronic workload (wCW), acute: chronic workload ratio (wACWR), training monotony (wTM), perceived load training strain indicators (wTS), and countermove- ment jump (CMJ) as indicators of wellness in one season and defined weekly variations. In addition, we analyzed the relationships between training load measurements and weekly reports. Methods: 16 elite young wrestlers were monitored daily with individual observations for 46 consecutive weeks throughout the season. Training load was obtained using the session rating of perceived effort. wSleep, wStress, wFatigue & wMuscle Soreness well-being were monitored daily using the Hooper index. Results: As a result of the analysis, it was found that there is a moderate relationship (r = 0.51, p = .003) between ACWR and w mean load (A.U.) and a high relationship (r = 0.81, p < .001) between monotony and strain. Conclusion: All variables other than ACWR, w mean load, strain, and monotony presented small and statistically insignificant relationships. These results provide coaches and practitioners with new insights into perceived loads and health changes during a season at the elite youth level.

Effect of active recovery using individual maximum exercise capacity: a pilot study

[Purpose] The intensity of active recovery (AR) for performance recovery is often determined using breath gas analyzers and other special equipment. However, such procedures are difficult to perform in the field or where facilities are inadequate. Although several AR methods using simple patient-derived information have been proposed, only a few have specifically addressed their immediate effects. The present study aimed to quantify the immediate effects of AR, which was determined using the maximum exercise capacity calculated using a physical fitness test without specialized devices. [Participants and Methods] Thirty-two healthy male participants were equally divided into AR and control groups. Each group performed squat jumps, followed by a recovery intervention of jogging at a set intensity in the AR group or rest in a seated position in the control group. Standing long jumps performed before and after the squat jumps as well as after the intervention were analyzed. [Results] The recovery rate for standing long jumps was significantly higher in the AR group than in the control group. [Conclusion] The results of this pilot study indicate that the implementation of AR based on maximum exercise capacity may enhance performance recovery and requires further validation in larger studies.

The anti-fatigue and sleep-aiding effects vary significantly among different recipes containing Ganoderma lucidum extracts

Aims

This study aims to delve into the anti-fatigue and sleep-aiding effects of various formulations containing Ganoderma lucidum extracts.

Materials and methods

PGB [incorporating Ganoderma lucidum extract (GE), broken Ganoderma lucidum spore powder (GB) and Paecilomyces hepiali mycelium (PH)] and GBS [composed of GE, GB, and Ganoderma sinense powder (GS)] were chosen as representative recipes for this study. Mice were treated with these recipes or key components of Ganoderma lucidum for 14 consecutive days. Subsequently, a weight-bearing swimming experiment was conducted to assess the mice's exhaustion time and evaluate the anti-fatigue properties of the recipes. Sleep-aiding effects were analyzed by measuring the sleep latency and duration. Furthermore, levels of blood lactic acid, serum urea nitrogen, hepatic glycogen, muscle glycogen, and malondialdehyde (MDA) were measured in the livers and muscles.

Key findings

The anti-fatigue abilities of the tested mice were significantly improved after treatment with PGB and their sleep quality improved as well with GBS treatment. PGB treatment for 14 days could significantly prolong the exhaustion time in weight-bearing swimming (from 10.1 ± 0.5 min to 15.2 ± 1.3 min). Meanwhile, glycogen levels in the livers and muscles were significantly increased, while the levels of serum lactic acid, serum urea nitrogen, and MDA in the livers and muscles were significantly decreased. In contrast, mice treated with GBS for 14 days experienced significant improvements in sleep quality, with shortened sleep latency (from 6.8 ± 0.7 min to 4.2 ± 0.4 min), extended sleep duration (from 88.3 ± 1.4 min to 152.5 ± 9.3 min), and decreased muscle MDA levels. These results indicated that Ganoderma lucidum extracts can be used for anti-fatigue and or aid in sleeping, depending on how they are prepared and administered.

Significance

This study provides experimental evidence and theoretical basis for the development of Ganoderma lucidum recipes that are specifically designed to help with anti-fatigue and sleep.

Effects of high-intensity sprint exercise on neuromuscular function in sprinters: the countermovement jump as a fatigue assessment tool

Background

High-intensity sprint exercises (HIS) are central to sprinter training and require careful monitoring of athlete muscle fatigue to improve performance and prevent injury. While the countermovement jump (CMJ) may be used to monitor neuromuscular fatigue (NMF), little is known about the specific effects from HIS. The purpose of this study is to investigate the effects of HIS on the CMJ to assess its utility for assessing NMF following HIS.

Methods

Ten male collegiate 400 m sprinters completed a 400 m sprint fatigue protocol and underwent five CMJ-testing sessions (baseline, 3 minutes, 10 minutes, 1 hour and 24 hours) over two days. Three CMJ trials, performed on a force plate, were completed each trial, with rating of perceived exertion (RPE) recorded as a subjective fatigue measure. Changes in RPE, CMJ variables, force-time and power-time curves at baseline and post fatigue were assessed.

Results

Significant changes were observed in most variables following the fatigue protocol. In particular, concentric mean power remained significantly lower after 24 hours compared to baseline. In addition, the force-time curves exhibited a significant reduction in all conditions following the fatigue protocol. This decline was most pronounced within 50-75%of the concentric phase relative to baseline measurements. Conclusion. Results indicate that the CMJ may be a useful tool for monitoring fatigue in at least 400 m sprinters. These data also indicate that HIS may disproportionately reduce force output in during concentric movement. These insights may improve training prescriptions and injury prevention strategies for sprint athletes.

The effect of vine tea (Ampelopsis grossedentata) extract on fatigue alleviation via improving muscle mass

ETHNOPHARMACOLOGICAL RELEVANCE

Vine Tea (VT, Ampelopsis grossedentata), boasts a venerable tradition in China, with a recorded consumption history exceeding 1200 years. Predominantly utilized by ethnic groups in southwest China, this herbal tea is celebrated for its multifaceted therapeutic attributes. Traditionally, VT has been employed to alleviate heat and remove toxins, exhibit anti-inflammatory properties, soothe sore throats, lower blood pressure, and fortify bones and muscles. In the realm of functional foods derived from plant resources, VT has garnered attention for its potential in crafting anti-fatigue beverages or foods, attributed to its promising efficacy and minimal side effects. Currently, in accordance with the Food Safety Standards set forth by the Monitoring and Evaluation Department of the National Health and Family Planning Commission in China, VT serves as a raw material in various beverages.

AIM OF THE STUDY

VT has an anti-fatigue or similar effect in folk. However, the underlying molecular mechanisms contributing to VT's anti-fatigue effects remain elusive. This study endeavors to investigate the influence of Vine Tea Aqueous Extract (VTE) on fatigue mitigation and to elucidate its operative mechanisms, with the objective of developing VTE as a functional beverage.

MATERIALS AND METHODS

The preparation of VTE involved heat extraction and freeze-drying processes, followed by the identification of its metabolites using UPLC-QTOF-MS to ascertain the chemical composition of VTE. A fatigue model was established using a forced swimming test in mice. Potential molecular targets were identified through network pharmacology, transcriptome analysis, and molecular docking. Furthermore, RT-PCR and Western blot techniques were employed to assess mRNA and protein expressions related to the AMPK and FoxO pathways.

RESULTS

VTE significantly prolonged the duration of swimming time in an exhaustive swimming test in a dose-dependent manner, while simultaneously reducing the concentrations of blood lactic acid (LA), lactate dehydrogenase (LDH), serum urea nitrogen (SUN), and creatine kinase (CK). Notably, the performance of the high-dose VTE group surpassed that of the well-recognized ginsenoside. VTE demonstrated a regulatory effect akin to ginsenoside on the AMPK energy metabolism pathway and induced downregulation in the expression of Gadd45α, Cdkn1a, FOXO1, and Fbxo32 genes, suggesting an enhancement in skeletal muscle mass. These findings indicate that VTE can improve energy metabolism and muscle mass concurrently.

CONCLUSIONS

VTE exhibits significant anti-fatigue effects, and its mechanism is intricately linked to the modulation of the AMPK and FoxO pathways. Crucially, no caffeine or other addictive substances with known side effects were detected in VTE. Consequently, vine tea shows substantial promise as a natural resource for the development of anti-fatigue beverages within the food industry.

High-level competition exercise and related fatigue are associated with stride and jumping characteristics in eventing horses

BACKGROUND

Fatigue and related injuries to the musculoskeletal system are among the most frequent reasons for the withdrawal of high-level eventing horses from the sport. The safety of both horse and rider is very important, and early detection of fatigue is crucial.

OBJECTIVES

To investigate elite eventing horses in competitive events focusing on biomechanical, cardiovascular and metabolic variables across the cross-country test and to identify their potential associations with fatigue.

STUDY DESIGN

Prospective observational exploratory field study.

METHODS

Observations on 54 cross-country tests of 33 horses at five competitive, high-level events were evaluated using sternal accelerometric analysis of stride parameters between and at the jumps. Blood lactate concentration and heart rate were determined 10 min after finishing. The differences in kinematic parameters between the course start and end were analysed with mixed models for repeated measures. Associations between blood lactate and heart rate recovery with the kinematic variables were quantified with Pearson correlation coefficients.

RESULTS

We observed numerous stride characteristics between the jumps and the jumps changing over time during the courses. Blood lactate concentrations were positively correlated with the mean maximal strike power at the jumps in the last minute of the course (r = 0.41; p < 0.001), and the latter was negatively correlated with the mean stride height over the jumps (r = -0.41; p = 0.003).

MAIN LIMITATIONS

The sample contained horses of varying breeds, sexes and ages, and different horses participated in different events.

CONCLUSIONS

We identified several kinematic changes during a cross-country test depending on event, speed and fatigue.

Fatigue in children using motor imagery and P300 brain-computer interfaces

BACKGROUND

Brain-computer interface (BCI) technology offers children with quadriplegic cerebral palsy unique opportunities for communication, environmental exploration, learning, and game play. Research in adults demonstrates a negative impact of fatigue on BCI enjoyment, while effects on BCI performance are variable. To date, there have been no pediatric studies of BCI fatigue. The purpose of this study was to assess the effects of two different BCI paradigms, motor imagery and visual P300, on the development of self-reported fatigue and an electroencephalography (EEG) biomarker of fatigue in typically developing children.

METHODS

Thirty-seven typically-developing school-aged children were recruited to a prospective, crossover study. Participants attended three sessions: (A) motor imagery-BCI, (B) visual P300-BCI, and (C) video viewing (control). The motor imagery task involved an imagined left- or right-hand squeeze. The P300 task involved attending to one square on a 3 × 3 grid during a random single flash sequence. Each paradigm had respective calibration periods and a similar visual counting game. Primary outcomes were self-reported fatigue and the power of the EEG alpha band both collected during resting-state periods pre- and post-task. Self-reported fatigue was measured using a 10-point visual analog scale. EEG alpha band power was calculated as the integrated power spectral density from 8 to 12 Hz of the EEG spectrum.

RESULTS

Thirty-two children completed the protocol (age range 7-16, 63% female). Self-reported fatigue and EEG alpha band power increased across all sessions (F(1,155) = 33.9, p < 0.001; F = 5.0(1,149), p = 0.027 respectively). No differences in fatigue development were observed between session types. There was no correlation between self-reported fatigue and EEG alpha band power change. BCI performance varied between participants and paradigms as expected but was not associated with self-reported fatigue or EEG alpha band power.

CONCLUSION

Short periods (30-mintues) of BCI use can increase self-reported fatigue and EEG alpha band power to a similar degree in children performing motor imagery and P300 BCI paradigms. Performance was not associated with our measures of fatigue; the impact of fatigue on useability and enjoyment is unclear. Our results reflect the variability of fatigue and the BCI experience more broadly in children and warrant further investigation.

Sports Diet and Oral Health in Athletes: A Comprehensive Review

Food and fluid supply is fundamental for optimal athletic performance but can also be a risk factor for caries, dental erosion, and periodontal diseases, which in turn can impair athletic performance. Many studies have reported a high prevalence of oral diseases in elite athletes, notably dental caries 20-84%, dental erosion 42-59%, gingivitis 58-77%, and periodontal disease 15-41%, caused by frequent consumption of sugars/carbohydrates, polyunsaturated fats, or deficient protein intake. There are three possible major reasons for poor oral health in athletes which are addressed in this review: oxidative stress, sports diet, and oral hygiene. This update particularly summarizes potential sports nutritional effects on athletes' dental health. Overall, sports diet appropriately applied to deliver benefits for performance associated with oral hygiene requirements is necessary to ensure athletes' health. The overall aim is to help athletes, dentists, and nutritionists understand the tangled connections between sports diet, oral health, and oral healthcare to develop mitigation strategies to reduce the risk of dental diseases due to nutrition.

Exercise-induced Musclin determines the fate of fibro-adipogenic progenitors to control muscle homeostasis

The effects of exercise on fibro-adipogenic progenitors (FAPs) are unclear, and the direct molecular link is still unknown. In this study, we reveal that exercise reduces the frequency of FAPs and attenuates collagen deposition and adipose formation in injured or disused muscles through Musclin. Mechanistically, Musclin inhibits FAP proliferation and promotes apoptosis in FAPs by upregulating FILIP1L. Chromatin immunoprecipitation (ChIP)-qPCR confirms that FoxO3a is the transcription factor of FILIP1L. In addition, the Musclin/FILIP1L pathway facilitates the phagocytosis of apoptotic FAPs by macrophages through downregulating the expression of CD47. Genetic ablation of FILIP1L in FAPs abolishes the effects of exercise or Musclin on FAPs and the benefits on the reduction of fibrosis and fatty infiltration. Overall, exercise forms a microenvironment of myokines in muscle and prevents the abnormal accumulation of FAPs in a Musclin/FILIP1L-dependent manner. The administration of exogenous Musclin exerts a therapeutic effect, demonstrating a potential therapeutic approach for muscle atrophy or acute muscle injury.

Plasma metabolomics reveals the intervention mechanism of different types of exercise on chronic unpredictable mild stress-induced depression rat model

OBJECTIVE

To study the effects of different types of exercise on the plasma metabolomics of chronic unpredictable mild stress (CUMS)-induced depressed rats based on 1H-NMR metabolomics techniques, and to explore the potential mechanisms of exercise for the treatment of depression. Rats were randomly divided into blank control group (C), CUMS control group (D), pre-exercise with CUMS group (P), CUMS with aerobic exercise group, CUMS with resistance exercise group (R), and CUMS with aerobic + resistance exercise group (E). The corresponding protocol intervention was applied to each group of rats. Body weight, sucrose preference and open field tests were performed weekly during the experiment to evaluate the extent of depression in rats. Plasma samples from each group of rats were collected at the end of the experiment, and then the plasma was analyzed by 1H-NMR metabolomics combined with multivariate statistical analysis methods to identify differential metabolites and perform metabolic pathway analysis. (1) Compared with the group D, the body weight, sucrose preference rate, and the number of crossings and standings in the different types of exercise groups were significantly improved (p < 0.05 or p < 0.01). (2) Compared to group C, a total of 15 differential metabolites associated with depression were screened in the plasma of rats in group D, involving 6 metabolic pathways. Group P can regulate the levels of 6 metabolites: valine, lactate, inositol, glucose, phosphocreatine, acetoacetic acid. Group A can regulate the levels of 6 metabolites: N-acetylglycoprotein, leucine, lactate, low density lipoprotein, glucose and acetoacetic acid. Group R can regulate the levels of 6 metabolites: choline, lactate, inositol, glucose, phosphocreatine and acetoacetic acid. Group E can regulate the levels of 5 metabolites: choline, citric acid, glucose, acetone and acetoacetic acid. The different types of exercise groups can improve the depressive symptoms in CUMS rats, and there are common metabolites and metabolic pathways for their mechanism of effects. This study provides a powerful analytical tool to study the mechanism of the antidepressant effect of exercise, and provides an important method and basis for the early diagnosis, prevention and treatment of depression.

Biomolecules of Muscle Fatigue in Metabolic Myopathies

Metabolic myopathies are a group of genetic disorders that affect the normal functioning of muscles due to abnormalities in metabolic pathways. These conditions result in impaired energy production and utilization within muscle cells, leading to limitations in muscle function with concomitant occurrence of related signs and symptoms, among which fatigue is one of the most frequently reported. Understanding the underlying molecular mechanisms of muscle fatigue in these conditions is challenging for the development of an effective diagnostic and prognostic approach to test targeted therapeutic interventions. This paper outlines the key biomolecules involved in muscle fatigue in metabolic myopathies, including energy substrates, enzymes, ion channels, and signaling molecules. Potential future research directions in this field are also discussed.

Signaling pathways regulated by natural active ingredients in the fight against exercise fatigue-a review

Exercise fatigue is a normal protective mechanism of the body. However, long-term fatigue hinders normal metabolism and exercise capacity. The generation and recovery from exercise fatigue involves alterations in multiple signaling pathways, mainly AMPK, PI3K/Akt, Nrf2/ARE, NF-κB, PINK1/Parkin, and BDNF/TrkB, as well as MAPK signaling pathways that mediate energy supply, reduction of metabolites, oxidative stress homeostasis, muscle fiber type switching, and central protective effects. In recent studies, a rich variety of natural active ingredients have been identified in traditional Chinese medicines and plant extracts with anti-fatigue effects, opening up the field of research in new anti-fatigue drugs. In this review we give an overview of the signaling pathways associated with the activity of natural food active ingredients against exercise fatigue. Such a comprehensive review is necessary to understand the potential of these materials as preventive measures and treatments of exercise fatigue. We expect the findings highlighted and discussed here will help guide the development of new health products and provide a theoretical and scientific basis for future research on exercise fatigue.

Maximizing choreography and performance in artistic swimming team free routines: the role of hybrid figures

Hybrid figures serve as an important component of artistic swimming, however, no prior research has investigated objective indicators for predicting total scores in competition. This study aimed to identify significance of hybrid figure (HF) elements in predicting total scores in artistic swimming competitions and compare these variables between the Beijing team trials and international official competitions. Eight HF variables were measured in the videos from the international artistic swimming competitions, with calibration and measurement of the variables leg height index and leg angle deviation being performed by means of Kinovea. Multiple linear regression was conducted to predict the total scores based on these variables investigated for the international teams, which showed 5 significant predictors including movement frequency, leg height index, leg angle deviation, mean pattern duration, and rotation frequency. Wilcoxon signed-rank test was used to determine the differences in the variables between the Beijing team and the international teams (top 5), which showed significant difference on movement frequency, leg angle deviation, leg height index and total score. When designing hybrid figures choreography of team free routine in artistic swimming, coaches should prioritize appropriate movement frequency, pattern changes and rotations over excessively long durations. Overly complex HF choreography may lead to a decline on performance in artistic swimming competition.

Maximizing plyometric training for adolescents: a meta-analysis of ground contact frequency and overall intervention time on jumping ability: a systematic review and meta-analysis

Plyometric training boosts adolescents' jumping ability, crucial for athletic success and health. However, the best total ground contact frequency (TGCF) and overall intervention time (OIT) for these exercises remain unclear. This meta-analysis aims to identify optimal TGCF and OIT in plyometric training for adolescents, focusing on countermovement jump (CMJ) and squat jump (SJ) outcomes. This systematic review encompassed five databases and included 38 studies with 50 randomized controlled experiments and 3347 participants. We used the Cochrane risk assessment tool for study quality and Review Manager 5.4 for data analysis. The current meta-analysis incorporated a total of 38 studies, comprising 50 sets of randomized controlled trials, to investigate the influence of different TGCFs and OITs on plyometric training. The Cochrane risk assessment tool indicated that all the included studies were classified as low risk. Various TGCFs in plyometric training positively affected CMJ and SJ heights in adolescents. The TGCF of less than 900 was ideal for enhancing CMJ, whereas more than 1400 was effective for SJ. The optimal OIT was 400-600 min, specifically, 500-600 min for CMJ and 400-500 min for SJ. Plyometric training improves jumping ability in adolescents. Lower ground contact frequency (< 900 contacts) enhances CMJ, while higher ground contact frequency (> 1400 contacts) is more effective for SJ. Optimal intervention time ranges from 400 to 600 min, with 500 to 600 min benefiting CMJ and 400 to 500 min improving SJ.

Student arousal, engagement, and emotion relative to Physical Education periods in school

BACKGROUND

Exercise has transient effects on cognition and mood, however the impact of Physical Education (PE) on cognitive and affective processes across the school day has not been examined.

METHOD

This study used wearables and questionnaires to track student arousal, engagement, and emotion across school days/periods following PE. Skin conductance, heart rate, heart rate variability, and self-reported engagement, arousal, and valence were analyzed for 23 students (age 15-17 years) on days with and without PE.

RESULTS

Sympathetic arousal was significantly higher for two hours following PE and there were stronger decreases in arousal across other classes relative to days without PE. On days with PE, engagement decreased, whereas valence increased from morning to afternoon.

CONCLUSION

These findings highlight the importance of considering acute effects of PE on learning across the entire school day, and demonstrates the feasibility of wearables to clarify how the timing of PE could positively or negatively affect self-regulation and learning.

Effect of Lactobacillus plantarum PS128 on neuromuscular efficiency after a half-marathon

Introduction: Lactobacillus plantarum PS128 (PS128) could be considered an antioxidant supplement to reduce muscle fatigue and improve exercise capacity recovery after vigorous exercise. Purpose: The purpose of this study is to investigate the effect of PS128 on muscle fatigue and electromyography (EMG) activity after a half-marathon (HM). Methods: The experimental design used a repeated-measures design with a double-blind approach. The participants either took two capsules of PS128 for 4 weeks as the PS128 group (PSG, n = 8) or took two capsules of a placebo for 4 weeks as the placebo group (PLG, n = 8) to ensure counterbalancing. The time points of the maximal voluntary isometric contraction (MVIC) and EMG activity test were set before probiotics were taken (baseline), 48 h before HM (Pre), and immediately at 0 h, 3 h, 24 h, 48 h, 72 h, and 96 h after HM. Results: EMG activity included median power frequency (MDF), integrated EMG (iEMG), and neuromuscular efficiency (peak torque/iEMG). The MVICs of knee extensors, analyzed by using an isokinetic dynamometer, showed a decrease from the Pre to 0 h (p = 0.0001), 3 h (p < 0.0001), 24 h (p < 0.0001), 48 h (p < 0.0001), 72 h (p = 0.0002), and 96 h (p = 0.0408) time points in the PLG. Sidak's multiple comparisons tests showed that the PLG was significantly lower than the PSG at 0 h (p = 0.0173), 3 h (p < 0.0001), 24 h (p < 0.0001), 48 h (p < 0.0001), 72 h (p < 0.0001), and 96 h (p = 0.0004) time points. The MDF of vastus medialis oblique (VMO) in the PLG was significantly decreased 24 h after HM and significantly lower than that in the PSG at all times points after HM. The iEMG of VMO in the PLG was significantly decreased 48 h after HM and significantly lower than that in the PSG at 0 h, 3 h, 24 h, 48 h, and 72 h after HM. Conclusion: The PS128 supplementation may prevent the decrease in MDF, iEMG, and peak torque after vigorous exercise. Recreational runners may consider implementing a probiotic supplementation regimen as a potential strategy to mitigate muscle fatigue following HM.

A Physical Fatigue Evaluation Method for Automotive Manual Assembly: An Experiment of Cerebral Oxygenation with ARE Platform

Due to the complexity of the automobile manufacturing process, some flexible and delicate assembly work relies on manual operations. However, high-frequency and high-load repetitive operations make assembly workers prone to physical fatigue. This study proposes a method for evaluating human physical fatigue for the manual assembly of automobiles with methods: NIOSH (National Institute for Occupational Safety and Health), OWAS (Ovako Working Posture Analysis System) and RULA (Rapid Upper Limb Assessment). The cerebral oxygenation signal is selected as an objective physiological index reflecting the human fatigue level to verify the proposed physical fatigue evaluation method. Taking auto seat assembly and automobile manual assembly as an example, 18 group experiments were carried out with the ARE platform (Augmented Reality-based Ergonomic Platform). Furthermore, predictions of metabolic energy expenditure were performed for experiments in Tecnomatix Jack. Finally, it is concluded that the proposed physical fatigue evaluation method can reflect the human physical fatigue level and is more accurate than the evaluation of metabolic energy consumption in Tecnomatix Jack because of the immersion that comes with the AR devices and the precision that comes with motion capture devices.

Identification of runner fatigue stages based on inertial sensors and deep learning

Introduction: Running is one of the most popular sports in the world, but it also increases the risk of injury. The purpose of this study was to establish a modeling approach for IMU-based subdivided action pattern evaluation and to investigate the classification performance of different deep models for predicting running fatigue. Methods: Nineteen healthy male runners were recruited for this study, and the raw time series data were recorded during the pre-fatigue, mid-fatigue, and post-fatigue states during running to construct a running fatigue dataset based on multiple IMUs. In addition to the IMU time series data, each participant's training level was monitored as an indicator of their level of physical fatigue. Results: The dataset was examined using single-layer LSTM (S_LSTM), CNN, dual-layer LSTM (D_LSTM), single-layer LSTM plus attention model (LSTM + Attention), CNN, and LSTM hybrid model (LSTM + CNN) to classify running fatigue and fatigue levels. Discussion: Based on this dataset, this study proposes a deep learning model with constant length interception of the raw IMU data as input. The use of deep learning models can achieve good classification results for runner fatigue recognition. Both CNN and LSTM can effectively complete the classification of fatigue IMU data, the attention mechanism can effectively improve the processing efficiency of LSTM on the raw IMU data, and the hybrid model of CNN and LSTM is superior to the independent model, which can better extract the features of raw IMU data for fatigue classification. This study will provide some reference for many future action pattern studies based on deep learning.

Association between physical activity and depressive symptoms in adolescents: A prospective cohort study

It remains uncertain whether a protective association between physical activity and depression exists among adolescents and what the optimal level of physical activity might be. This study aimed to estimate the associations of physical activity levels with depressive symptoms and new-onset depression, while identifying potential modifying factors influencing the relationships. In this cohort study, we initially enrolled 1957 participants at baseline and followed up with 1738 of them after two years. Our analysis focused on data from 1482 students who provided complete information on both physical activity and depressive symptoms. Generalized linear regression and restricted cubic spline regression models were performed. Our adjusted models revealed that engaging in 4-7 h/week of moderate-to-vigorous physical activity (MVPA) at baseline was negatively associated with subsequent depressive symptoms and new-onset depression compared to the non-MVPA group. However, exceeding 7 h/week of MVPA did not provide substantial benefits. Furthermore, drinking and screen time potentially modified the relationship between MVPA and new-onset depression. Our findings suggest that 4-7 h of MVPA per week may be an appropriate level to reduce depressive symptoms in adolescents. Moreover, individual behaviors (e.g., drinking and screen time) warrant heightened attention in interventions targeting the reduction of depression in this population.

Effect of Yeast-Derived Peptides on Skeletal Muscle Function and Exercise-Induced Fatigue in C2C12 Myotube Cells and ICR Mice

In our previous study, the antioxidant peptides (XHY69AP, AP-D, YPLP, and AGPL) were obtained from potential probiotic yeast (Yamadazyma triangularis XHY69), which was selected by our lab from dry-cured ham. This work aimed to explore the effects of yeast-derived peptides on skeletal muscle function and muscle fatigue. Results showed that yeast-derived peptides up-regulated slow-twitch fiber expression and down-regulated fast-twitch fiber expression in C2C12 cells (p < 0.05). The peptides improved mitochondrial membrane potential, adenosine triphosphate generation, and expression of cytochrome-relative genes, thus promoting mitochondrial function. Among these peptides, YPLP up-regulated the relative gene expression of the AMP-activated protein kinase (AMPK) pathway and activated AMPK by phosphorylation. Moreover, YPLP could prolong treadmill time, increase muscle and liver glycogen contents, reduce lactic acid and urea nitrogen contents, and alleviate muscle tissue injury in ICR exercise mice. These results demonstrate that yeast-derived peptides could change the muscle fiber composition, improve muscle function, and relieve muscle fatigue.

Blood-Based Markers for Skeletal and Cardiac Muscle Function in Eventing Horses before and after Cross-Country Rides and How They Are Influenced by Plasma Volume Shift

Horses competing in cross-country tests are subjected to high physical demands. Within the scope of this prospective longitudinal study, blood values of 20 elite eventing horses were examined before and after two- to four-star cross-country rides. The aim was to find out whether blood-based markers for skeletal muscle and cardiac muscle function change after cross-country exercise. Parameters that provide information about fluid balance, muscle enzymes, metabolites and cardiac muscle-specific markers were investigated. We developed an approach to eliminate the concentration changes caused by reduced plasma volume. Parameters were measured pre, 10 and 30 min post exercise and the next morning and were evaluated using a mixed model. Thirty minutes after exercise, most parameter concentrations changed in an exercise-dependent manner. The next morning, most exercise-related markers recovered rapidly, while creatine kinase (CK) (26% increase; p = 0.008) and lactate dehydrogenase (LDH) (15% increase; p < 0.001) showed a declining but sustained increase. Cardiac troponin I (cTnI) increased above the reference range in 40 of the 55 rides (73%) and in 18 of 20 horses in the morning after exercise.

Functional Near-Infrared Spectroscopy-Based Evidence of the Cerebral Oxygenation and Network Characteristics of Upper Limb Fatigue

OBJECTIVE

The objective of this research is to better understand the effects of upper limb fatigue on the cerebral cortex. The aim of this study was to investigate the characteristics of cerebral oxygenation and cortical functional connectivity in healthy adults after upper limb fatigue using functional near-infrared spectroscopy (fNIRS).

METHODS

Nineteen healthy adults participated in this study. The participants began exercising on an arm crank ergometer with no load, which was then increased by 0.2 kg per minute, maintaining a speed of at least 90 revolutions per minute during the exercise. Functional near-infrared spectroscopy covering the prefrontal cortex and motor area was used to monitor brain activity during rest and exercise. Heart rate and RPE were monitored during exercise to evaluate the degree of fatigue. Paired-sample t-tests were used to examine differences in the concentration of oxygenated hemoglobin (HbO2) and functional connectivity before and after fatigue.

RESULTS

All participants completed the exercise test that induced fatigue. We observed a significant decrease in HbO2 levels in the prefrontal and motor areas after exercise. In addition, brain network features showed a significant decrease in functional connectivity between the left and right motor cortices, between the motor and prefrontal cortices, and between both prefrontal cortices after fatigue.

CONCLUSION

This study demonstrates that, in healthy adults, exercise-induced fatigue in the upper limbs significantly affects brain function. In particular, it leads to reduced functional connectivity between the motor cortex and the prefrontal cortex.

Predictors of lower exercise capacity in patients with cancer

Maintaining cancer patients' exercise capacity and therefore patients' ability to live a self-determined life is of huge importance, but little is known about major determinants. We sought to identify determinants of exercise capacity in patients with a broad spectrum of cancer types, who were already receiving cancer treatment or about to commence such therapy. Exercise capacity was assessed in 253 consecutive patients mostly suffering from advanced cancer using the 6-min walk test (6-MWT). All patients underwent echocardiography, physical examination, resting electrocardiogram, hand grip strength (HGS) measurement, and laboratory assessments. Patients were divided into two groups according to the median distance in the 6-MWT (459 m). Patients with lower exercise capacity were older, had significantly lower HGS and haemoglobin and higher values of high sensitive (hs) Troponin T and NT-proBNP (all p < 0.05). Whilst the co-morbidity burden was significantly higher in this group, no differences were detected for sex, body mass index, tumor type, or cachexia (all p > 0.2). Using multivariable logistic regression, we found that the presence of anaemia (odds ratio (OR) 6.172, 95% confidence interval (CI) 1.401-27.201, p = 0.016) as well as an increase in hs Troponin T (OR 3.077, 95% CI 1.202-5.301, p = 0.019) remained independent predictors of impaired exercise capacity. Increasing HGS was associated with a reduced risk of a lower exercise capacity (OR 0.896, 95% CI 0.813-0.987, p = 0.026). Screening patients for elevated hs troponin levels as well as reduced HGS may help to identify patients at risk of lower exercise capacity during cancer treatment.

Anti-fatigue effect of tormentic acid through alleviating oxidative stress and energy metabolism-modulating property in C2C12 cells and animal models

BACKGROUND/OBJECTIVES

Oxidative stress is caused by reactive oxygen species and free radicals that accelerate inflammatory responses and exacerbate fatigue. Tormentic acid (TA) has antioxidant and anti-inflammatory properties. Thus, the aim of present study is to determine the fatigue-regulatory effects of TA in H₂O₂-stimulated myoblast cell line, C2C12 cells and treadmill stress test (TST) and forced swimming test (FST) animal models.

MATERIALS/METHODS

In the in vitro study, C2C12 cells were pretreated with TA before stimulation with H₂O₂. Then, malondialdehyde (MDA), lactate dehydrogenase (LDH), creatine kinase (CK) activity, tumor necrosis factor (TNF)-α, interleukin (IL)-6, superoxide dismutase (SOD), catalase (CAT), glycogen, and cell viability were analyzed. In the in vivo study, the ICR male mice were administered TA or distilled water orally daily for 28 days. FST and TST were then performed on the last day. In addition, biochemical analysis of the serum, muscle, and liver was performed.

RESULTS

TA dose-dependently alleviated the levels of MDA, LDH, CK activity, TNF-α, and IL-6 in H₂O₂-stimulated C2C12 cells without affecting the cytotoxicity. TA increased the SOD and CAT activities and the glycogen levels in H₂O₂-stimulated C2C12 cells. In TST and FST animal models, TA decreased the FST immobility time significantly while increasing the TST exhaustion time without weight fluctuations. The in vivo studies showed that the levels of SOD, CAT, citrate synthase, glycogen, and free fatty acid were increased by TA administration, whereas TA significantly reduced the levels of glucose, MDA, LDH, lactate, CK, inflammatory cytokines, alanine transaminase, aspartate transaminase, blood urea nitrogen, and cortisol compared to the control group.

CONCLUSIONS

TA improves fatigue by modulating oxidative stress and energy metabolism in C2C12 cells and animal models. Therefore, we suggest that TA can be a powerful substance in healthy functional foods and therapeutics to improve fatigue.

The demographic features of fatigue in the general population worldwide: a systematic review and meta-analysis

BACKGROUND

Fatigue is one of the most common subjective symptoms that impairs daily life and predict health-related events. This study aimed to estimate the prevalence of fatigue in the global population.

METHODS

PubMed and the Cochrane Library were used to search for relevant articles from inception to December 31, 2021. Studies with prevalence data of fatigue in the general population were selected and reviewed by three authors independently and cross-checked. Regarding subgroups, adults (≥18 years), minors (<18 years), and specific occupation population (participants in each study being limited to a specific occupational group), and fatigue types and severity, meta-analysis was conducted to produce point estimates and 95% confidence intervals (95% CI).

RESULTS

From the initial 3,432 studies, 91 studies accounting for 115 prevalence data points (623,624 participants) were finally selected. The prevalence of general fatigue (fatigue lasting < 6 months, or fatigue of unspecified duration) was 20.4% (95% CI, 16.7-25.0) in adults, 11.7% (95% CI, 5.2-26.6) in minors, and 42.3% (95% CI, 33.0-54.2) in specific occupations. Chronic fatigue (fatigue lasting more than 6 months) affected 10.1% (95% CI, 8.2-12.5) of adults, 1.5% (95% CI, 0.5-4.7) of minors, and 5.5% (95% CI, 1.4-21.6) of subjects in specific occupations. There was an overall female-predominant prevalence for all subgroup analyses, with a total odds ratio of 1.4 (95% CI, 1.3-1.6). Regarding the severity and presence of medical causes, the total prevalence of moderate fatigue [14.6% (95% CI, 9.8-21.8)] was 2.4-fold that of severe fatigue [6.1% (95% CI, 3.4-11.0)], while unexplained fatigue (fatigue experienced by individuals without any underlying medical condition that can explain the fatigue) was ~2.7-fold that of explained fatigue (fatigue experienced by individuals with a medical condition that can explain the fatigue); as proportion of 40.0% of physical, 8.6% of mental, and 28.4% of mixed cause.

CONCLUSIONS

This study has produced the first comprehensive picture of global fatigue prevalence in the general population, which will provide vital reference data contributing to fatigue-related research, including the prevention of diseases.

SYSTEMATIC REVIEW REGISTRATION

Identifier: CRD42021270498.

Calcium, Phosphate, and Vitamin D Status in Patients with Sarcoidosis-Associations with Disease Activity and Symptoms

Sarcoidosis is a systemic granulomatous disease with a variety of presentations. One of the known symptoms are altered vitamin D metabolism and hypercalcemia. In our study, we aimed to assess associations between disease activity, inflammatory parameters, and vitamin D and calcium status. The secondary aim was to find any dependencies between calcium and vitamin D metabolism and fatigue and quality of life in patients with sarcoidosis. We enrolled 58 patients with sarcoidosis (47 classified as active disease, 11 classified as non-active) and compared them with 25 healthy volunteers. Calcium concentration was significantly higher in the study group than in healthy controls. It correlated with some inflammatory markers but not with vitamin D status. Not calcium nor vitamin D, but phosphate concentration correlated with life quality was assessed with the use of the Sarcoidosis Health Questionnaire. An association between phosphate concentration and fatigue was also noted, but it did not reach statistical significance. Calcium concentration was higher in patients with sarcoidosis, but it was not an indicator of the disease activity, while phosphate concentration was significantly lower in patients with active sarcoidosis.

The molecular athlete: exercise physiology from mechanisms to medals

Human skeletal muscle demonstrates remarkable plasticity, adapting to numerous external stimuli including the habitual level of contractile loading. Accordingly, muscle function and exercise capacity encompass a broad spectrum, from inactive individuals with low levels of endurance and strength to elite athletes who produce prodigious performances underpinned by pleiotropic training-induced muscular adaptations. Our current understanding of the signal integration, interpretation, and output coordination of the cellular and molecular mechanisms that govern muscle plasticity across this continuum is incomplete. As such, training methods and their application to elite athletes largely rely on a "trial-and-error" approach, with the experience and practices of successful coaches and athletes often providing the bases for "post hoc" scientific enquiry and research. This review provides a synopsis of the morphological and functional changes along with the molecular mechanisms underlying exercise adaptation to endurance- and resistance-based training. These traits are placed in the context of innate genetic and interindividual differences in exercise capacity and performance, with special consideration given to aging athletes. Collectively, we provide a comprehensive overview of skeletal muscle plasticity in response to different modes of exercise and how such adaptations translate from "molecules to medals."

Physical Exercise Decreases Endoplasmic Reticulum Stress in Central and Peripheral Tissues of Rodents: A Systematic Review

Endoplasmic reticulum stress (ER stress) affects many tissues and contributes to the development and severity of chronic diseases. In contrast, regular physical exercise (PE) has been considered a powerful tool to prevent and control several chronic diseases. The present systematic review aimed to evaluate the impact of different PE protocols on ER stress markers in central and peripheral tissues in rodents. The eligibility criteria were based on PICOS (population: rodents; intervention: physical exercise/physical training; control: animals that did not undergo training; outcomes: endoplasmic reticulum stress; studies: experimental). The PubMed/Medline, Science Direct, Scopus, and Scielo databases were analyzed systematically. Quality assessment was performed using SYRCLE's risk of bias tool for animal studies. The results were qualitatively synthesized. Initially, we obtained a total of 2.490 articles. After excluding duplicates, 30 studies were considered eligible. Sixteen studies were excluded for not meeting the eligibility criteria. Therefore, 14 articles were included. The PE protocol showed decreased levels/expression of markers of ER stress in the central and peripheral tissues of rodents. PE can decrease ER stress by reducing cellular stress in the cardiac, brain, and skeletal muscle tissues in rodents. However, robust PE protocols must be considered, including frequency, duration, and intensity, to optimize the PE benefits of counteracting ER stress and its associated conditions.

Effects of an individualised exercise programme plus Behavioural Change Enhancement (BCE) strategies for managing fatigue in frail older adults: a cluster randomised controlled trial

BACKGROUND

To the best of our knowledge, although ageing-induced fatigue could cause adverse outcomes such as frailty, there is currently no intervention for it. This study evaluated the effects of an individualised exercise programme with/without BCE strategies on reducing fatigue in older adults.

METHODS

A three-armed cluster-randomised controlled trial (RCT) was conducted with 184 participants (mean age: 79.1 ± 6.4; mean frailty score: 2.8 + 0.8) from 21 community centres (ClinicalTrials.gov: NCT03394495). They were randomised into either: the COMB group (n = 64), receiving 16 weeks of exercise training plus the BCE programme; the EXER group (n = 65), receiving exercise training and health talks; or the control group (n = 55), receiving only health talks. Fatigue was assessed using the Multi-dimensional Fatigue Inventory (range: 20 to 100, with higher scores indicating higher fatigue levels) at baseline, and immediately, 6 months, and 12 months post-intervention.

RESULTS

The GEE analyses showed significant interaction (time x group) between the COMB and control groups immediately (p < 0.001), 6 months (p < 0.001), and 12 months (p < 0.001) post-intervention. Comparing the COMB and EXER groups, there was a significant interaction immediately (p = 0.013) and at 12 months post-intervention (p = 0.007). However, no significant difference was seen between the EXER group and control group at any time point.

CONCLUSIONS

The COMB intervention showed better immediate and sustainable effects (i.e., 12 months after the intervention) on reducing fatigue in frail older adults than exercise training or health education alone.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT03394495), registered on 09/01/2018.