Exercise-induced Muscle Fatigue Research Articles

Differential Effects of Exercise Intensity and Tolerable Duration on Exercise-Induced Diaphragm and Expiratory Muscle Fatigue.

We investigated the effect of exercise intensity and tolerable duration on the development of exercise-induced diaphragm and expiratory muscle fatigue. Ten healthy adults (25 ± 5 y; 2 females) cycled to intolerance on three separate occasions: 1) 5% below critical power (<CP; heavy intensity); 2) ~25% of the difference (Δ) between CP and peak ramp-incremental power (Δ25; severe intensity 'longer'); and 3) ~50% Δ (Δ50; severe intensity 'shorter'). Diaphragm and expiratory muscle fatigue were quantified as a pre- to 5 min post-exercise reduction in magnetically evoked transdiaphragmatic (Pditw) and gastric (Pgatw) twitch pressures, respectively. Exercise time was 34.5 ± 6.2 min, 10.2 ± 2.6 min, and 4.9 ± 0.7 min for <CP, Δ25, and Δ50 conditions, respectively. Oxygen uptake (V̇O2) at end-exercise was lower during <CP (87 ± 6% V̇O2peak) relative to Δ25 (97 ± 4% V̇O2peak) and Δ50 (99 ± 4% V̇O2peak) (P < 0.001). The pre- to post-exercise decrease in Pditw was greater after Δ25 (-22 ± 12%) vs. <CP (-13 ± 8%; P = 0.0499) and Δ50 (-14 ± 12%; P = 0.045). Conversely, the decrease in Pgatw from pre- to post-exercise was not different between trials (<CP: -23 ± 15%; ∆25: -29 ± 15%; ∆50: -25 ± 16%) (P > 0.05). In conclusion, the magnitude of exercise-induced diaphragm fatigue was greater after longer duration severe exercise than after shorter duration severe and heavy exercise. By contrast, the magnitude of exercise-induced expiratory muscle fatigue was unaffected by exercise intensity and tolerable duration.

Relationship between Fear-Avoidance Beliefs and Reaction Time Changes Prior to and following Exercise-Induced Muscle Fatigue in Chronic Low Back Pain.

Reaction time is a reliable indicator of the velocity and efficiency of neuromuscular control and may be associated with fear-avoidance beliefs. However, the effect of exercise-induced muscle fatigue on reaction time in chronic low back pain (cLBP) and its relationship with fear-avoidance beliefs remains poorly understood. This study aimed to reveal the relationship between fear-avoidance beliefs and reaction time changes before and after exercise-induced muscle fatigue in cLBP. Twenty-five patients with cLBP were tested by the Biering-Sorensen test (BST) to induce exhaustive muscle fatigue. Total reaction time (TRT), premotor time (PMT), and electromechanical delay (EMD) of dominated deltoid muscle were recorded by surface electromyography during the arm-raising task with visual cues before and after muscle fatigue. The mean difference (MD) of TRT (MDTRT), PMT (MDPMT), and EMD (MDEMD) was calculated from the changes before and after muscle fatigue. Fear-avoidance beliefs questionnaire (FABQ) was applied to evaluate fear-avoidance beliefs before muscle fatigue. In addition, the duration time of BST was recorded for each subject. TRT and PMT of dominated deltoid muscle were prolonged after exercise-induced muscle fatigue (Z = 3.511, p < 0.001; t = 3.431, p = 0.001), while there was no statistical difference in EMD (Z = 1.029, p = 0.304). Correlation analysis showed that both the MDTRT and MDPMT were positively correlated with FABQ (r = 0.418, p = 0.042; r = 0.422, p = 0.040). These findings suggested that we should pay attention to both muscle fatigue-induced reaction time delay in cLBP management and the possible psychological mechanism involved in it. Furthermore, this study implied that FABQ-based psychotherapy might serve as a potential approach for cLBP treatment by improving reaction time delay. This trial is registered with ChiCTR2300074348.

Effects of auriculotherapy on muscle fatigue: A randomized crossover trial

ObjectiveThis study aimed investigate the effect of auriculotherapy on exercise-induced muscle fatigue, isometric torque production, and surface electromyographic activity (EMG). MethodsDesign: Randomized Crossover Trial. The sample consisted of 18 males’ volunteers who exercised at least twice a week. The sample was randomly assigned to two groupsPlacebo Group (n = 9) and Treated Group (n = 9), and after seven days, the groups were crossed. The data analysis included 18 participants in each group. Main outcome measureThe muscle fatigue index, force production rate, and EMG of the quadriceps were used for evaluation. The evaluation moments included baseline pre-fatigue, baseline post-fatigue, 48 h post-intervention pre-fatigue, and 48 h post-intervention post-fatigue. Mixed two-way test ANOVA was used to compare times and groups. ResultsThe fatigue index for peak torque and work showed no significant effect on time, groups, or interaction (p > 0.05). However, for isometric torque, force production rate, and EMG median frequency and average, the results indicate a positive change in values over time (p < 0.05) (with little practical relevance), with no differences observed between the groups or interaction (p > 0.05). ConclusionsIn conclusion, auriculotherapy had no effect on exercise-induced muscle fatigue, isometric torque production, and surface electromyographic activity.

The effects of age on dyspnea and respiratory mechanical and neural responses to exercise in healthy men.

The respiratory muscle pressure generation and inspiratory and expiratory neuromuscular recruitment patterns in younger and older men were compared during exercise, alongside descriptors of dyspnea. Healthy younger (n = 8, 28 ± 5 years) and older (n = 8, 68 ± 4 years) men completed a maximal incremental cycling test. Esophageal, gastric (Pga ) and transdiaphragmatic pressures, and electromyography (EMG) of the crural diaphragm were measured using a micro-transducer and EMG catheter. EMG of the parasternal intercostals, sternocleidomastoids, and rectus abdominis were measured using skin surface electrodes. After the exercise test, participants completed a questionnaire to evaluate descriptors of dyspnea. Pga at end-expiration, Pga expiratory tidal swings, and the gastric pressure-time product (PTPga ) at absolute and relative minute ventilation were higher (p < 0.05) for older compared to younger men. There were no differences in EMG responses between older and younger men. Younger men were more likely to report shallow breathing (p = 0.005) than older men. Our findings showed younger and older men had similar respiratory neuromuscular activation patterns and reported different dyspnea descriptors, and that older men had greater expiratory muscle pressure generation during exercise. Greater expiratory muscle pressures in older men may be due to compensatory mechanisms designed to offset increasing airway resistance due to aging. These results may have implications for exercise-induced expiratory muscle fatigue in older men.

Effects of Muscle Fatigue and Recovery on the Neuromuscular Network after an Intermittent Handgrip Fatigue Task: Spectral Analysis of Electroencephalography and Electromyography Signals

Mechanisms underlying exercise-induced muscle fatigue and recovery are dependent on peripheral changes at the muscle level and improper control of motoneurons by the central nervous system. In this study, we analyzed the effects of muscle fatigue and recovery on the neuromuscular network through the spectral analysis of electroencephalography (EEG) and electromyography (EMG) signals. A total of 20 healthy right-handed volunteers performed an intermittent handgrip fatigue task. In the prefatigue, postfatigue, and postrecovery states, the participants contracted a handgrip dynamometer with sustained 30% maximal voluntary contractions (MVCs); EEG and EMG data were recorded. A considerable decrease was noted in EMG median frequency in the postfatigue state compared with the findings in other states. Furthermore, the EEG power spectral density of the right primary cortex exhibited a prominent increase in the gamma band. Muscle fatigue led to increases in the beta and gamma bands of contralateral and ipsilateral corticomuscular coherence, respectively. Moreover, a decrease was noted in corticocortical coherence between the bilateral primary motor cortices after muscle fatigue. EMG median frequency may serve as an indicator of muscle fatigue and recovery. Coherence analysis revealed that fatigue reduced the functional synchronization among bilateral motor areas but increased that between the cortex and muscle.

Differences in Medial and Lateral Gastrocnemius Stiffness after Exercise-Induced Muscle Fatigue.

Muscles are affected at the cellular level by exercised-induced fatigue, inducing changes in their stiffness. Examining muscle stiffness can improve the knowledge of various pathologic conditions, such as pain and injury. The objective of this study was to examine the stiffness of the medial gastrocnemius (MG) muscle and the lateral gastrocnemius (LG) muscle to determine the changes in stiffness, and to assess the differences in the stiffness between the MG and the LG, as affected by muscle fatigue measured using shear wave elastography (SWE) and a MyotonPRO after inducing muscle fatigue. A total of 35 healthy young adults participated in the study. The stiffness of the MG and the LG were assessed before and after a muscle fatigue protocol (MFP), which included three sets of 50 eccentric contractions of the calf muscles of the dominant leg, at rest, and at maximum voluntary contraction (MVC). The measurements were taken with SWE and the MyotonPRO simultaneously. Compared to baseline, the resting stiffness of the MG and the LG significantly increased immediately, 24 h, and 48 h after muscle fatigue (p < 0.05); however, during MVC, the stiffness of the MG decreased (p < 0.05) and that of the LG showed no change (p > 0.05). When the stiffness of the MG and the LG were compared before and after the MFP, changes in the stiffness of the MG were significantly greater than those in the LG (p < 0.05). This signifies that the MG was more affected by the exercise-induced muscle fatigue than was the LG. The assessment of musculoskeletal tissue and its characteristics, before and after eccentric exercise, is crucial in the prevention of overuse injuries associated with repeated exposure to both low and high levels of force.

EFEITOS DO BANHO MEDICINAL CHINÊS NA FADIGA MUSCULAR ESPORTIVA DOS ATLETAS

ABSTRACT Introduction: The Fifth International Conference on Sports Biochemistry defines sports fatigue as the physiological process of dysfunction at a certain level or inability to maintain predetermined exercise intensity. When left untreated, it can cause adverse effects to the musculoskeletal system. Natural alternatives for controlling sports fatigue exist in Chinese culture, but scientific research is needed to determine the effectiveness of these treatments. Objective: This study aimed to verify the effect of traditional Chinese medicinal baths on athletes’ muscle fatigue. Methods: 100 athletes with exercise-induced muscle fatigue were randomly divided into two groups. The control group received ganglioside injection combined with therapeutic exercise protocols, while the experimental group received the medicinal bath based on traditional Chinese medicine. Tonus of adductors, ischiotibials, gastrocnemius, in addition to lower limb motor function, was evaluated. Results: The total effective rate (90.8%) of the observation group was higher than that of the control group (72.3%), and the difference was statistically significant (P&lt;0.05). After treatment, adductor, hamstring, and gastrocnemius muscle tension in the observation group were lower than the control group (P&lt;0.05). Gross motor function assessment score (GMFM-88), Berg Balance Scale (BBS), 10m walking speed on a 20cm wide walkway (MWS) in the observation group were higher than those in the control group (P&lt;0.05). Conclusion: Chinese herbal lavender lotion combined with suspension exercise can effectively improve the body's muscle strength after exercises, accelerate the recovery of muscle strength, and significantly reduce exercise-induced muscle fatigue. Evidence Level II; Therapeutic Studies - Investigating the result.

The Effects Of Age On Exercise-induced Abdominal Muscle Fatigue In Healthy Younger And Older Men.

PURPOSE: Older men have a greater amount of expiratory flow limitation and abdominal muscle pressure generation during high intensity exercise compared to younger men. This may result in a higher prevalence of exercise-induced abdominal muscle fatigue. However, this is currently unknown. Therefore, we investigated the effects of age on exercise-induced abdominal muscle fatigue in healthy younger and older men. METHODS: Eight younger (29 ± 4 years) and eight older (69 ± 4 years) men completed a constant load cycling test at 85% of maximal power output to the limit of tolerance. The percentage of expiratory flow limitation was quantified by superimposing pre-exercise maximum flow volume loops with tidal breaths meeting or exceeding the expiratory portion of the maximum flow volume loops. Gastric pressures were measured using a micro-transducer esophageal catheter. To determine supramaximal nerve stimulation, three single twitches were obtained at intensities of 50, 60, 70, 80, 85, 90, 95, and 100% of maximal stimulator output pre-exercise. Fatigue of the abdominal muscles was assessed by measuring the reduction in magnetically evoked gastric twitch pressure (Pga,tw) responses pre- and post-exercise at 0, +15 and + 30 min. Abdominal muscle fatigue was defined as ≥10% reduction in potentiated Pga,tw relative to pre-exercise values. Comparisons between younger and older men for the prevalence of abdominal muscle fatigue were made using Fisher’s exact test. RESULTS: As the power output of the stimulator increased there were proportional increases in Pga,tw. Supramaximality was achieved from 90% for younger men (P ≥ 0.230) and from 95% for older men (P ≥ 0.940). Older men had higher expiratory flow limitation and gastric pressure time products than younger men (P < 0.05). Five of eight (63%) younger men (-28 ± 14%) vs. seven of eight (88%) older men (-37 ± 18) exhibited abdominal muscle fatigue (P = 0.038). CONCLUSION: We investigated the effects of age on exercise-induced abdominal muscle fatigue in healthy younger and older men. Older men experienced a greater amount of expiratory flow limitation and abdominal muscle pressure generation compared to younger men which resulted in a higher prevalence of exercise-induced abdominal muscle fatigue.

Resting-state Brain Network Analysis And Prediction: An Eeg Study On Exercise-induced Muscle Fatigue

PURPOSE: Exercise-induced muscle fatigue is a complex physiological phenomenon involving the central and peripheral nervous systems, and the tolerance of fatigue has a large variability among subjects. The present study has been designed to find an effective way for predicting muscle fatigue and probing the neural mechanism of fatigue by a resting-state EEG network. METHODS: In this study, thirteen elite athletes (female) were enrolled to take part in an elbow flexion and extension task. Five-minute before- and after-fatigue-exercise resting-state EEG and fatiguing task electromyography (EMG) data were recorded. Based on the graph theory, we constructed the resting-state EEG network, and compared the network differences before- and after-task. To further validate, the correlation between the before-fatigue resting-state EEG network properties and the EMG-related fatigue indexes Mean power frequency(MPF) during exercise was profiled. Finally, a prediction model based on the before-fatigue resting-state EEG network property, including Clustering coefficient (CC), local efficiency (Le), global efficiency (Ge), and characteristic path length (CPL), was established to predict the EMG related fatigue indexes after fatigue. RESULTS: Firstly, the results of this study demonstrated a significant relationship between the resting-state brain network and muscle fatigue during exercise(P < 0.05). Secondly, we also validate that a significant relationship between resting-state brain network properties and MPF (P < 0.05). Finally, the study proved that the before-fatigue resting-state EEG network single property could predict the fatigue tolerance for individual subject accurately (CC: r = 0.651, P < 0.05; CPL: r = 0.592, P < 0.05; Ge: r = 0.603, P < 0.05; Le: r = 0.654, P < 0.05). CONCLUSION: In all, the resting-state brain network may provide indicators for the monitoring and prediction of muscle fatigue in athletes, in the meantime, provide biological markers for recognition and regulation of muscle fatigue based on BCI.

Predicting individual muscle fatigue tolerance by resting-state EEG brain network *

Objective. Exercise-induced muscle fatigue is a complex physiological phenomenon involving the central and peripheral nervous systems, and fatigue tolerance varies across individuals. Various studies have emphasized the close relationships between muscle fatigue and the brain. However, the relationships between the resting-state electroencephalogram (rsEEG) brain network and individual muscle fatigue tolerance remain unexplored. Approach. Eighteen elite water polo athletes took part in our experiment. Five-minute before- and after-fatigue-exercise rsEEG and fatiguing task (i.e. elbow flexion and extension) electromyography (EMG) data were recorded. Based on the graph theory, we constructed the before- and after-task rsEEG coherence network and compared the network differences between them. Then, the correlation between the before-fatigue rsEEG network properties and the EMG fatigue indexes when a subject cannot keep on exercising anymore was profiled. Finally, a prediction model based on the before-fatigue rsEEG network properties was established to predict fatigue tolerance. Main results. Results of this study revealed the significant differences between the before- and after-exercise rsEEG brain network and found significant high correlations between before-exercise rsEEG network properties in the beta band and individual muscle fatigue tolerance. Finally, an efficient support vector regression (SVR) model based on the before-exercise rsEEG network properties in the beta band was constructed and achieved the accurate prediction of individual fatigue tolerance. Similar results were also revealed on another 30 subject swimmer data set further demonstrating the reliability of predicting fatigue tolerance based on the rsEEG network. Significance. Our study investigates the relationship between the rsEEG brain network and individual muscle fatigue tolerance and provides a potential objective physiological biomarker for tolerance prediction and the regulation of muscle fatigue.

Effects of exercise-induced muscle fatigue on V̇O2 slow component during heavy constant load exercise

article: Effects of exercise-induced muscle fatigue on V̇O2 slow component during heavy constant load exercise - Gazzetta Medica Italiana - Archivio per le Scienze Mediche 2022 April;181(4):225-33 - Minerva Medica - Journals

Study of the anti-fatigue properties of macamide, a key component in maca water extract, through foodomics and gut microbial genomics

Lepidium meyenii Walp. is a type of food used to fight fatigue, and macamides is the key anti-fatigue component in Lepidium meyenii Walp. water extract (Maca). The mechanisms of action of several foods with anti-fatigue properties lie in the oxidative balance of tissues; however, little attention has been given to the microbiome. The gut microbial community is closely related to dietary choices, as well as exercise-induced skeletal muscle fatigue. As such, this study used a foodomics approach to analyze the anti-fatigue properties of maca amide, a key component in maca, on the gut microbiome. The key components in maca were identified, and after validation in a mouse model, an analysis of the gut microbiome was performed. The results of database searches and network analyses showed that the key anti-fatigue component of maca was N-benzyl-9Z, 12Z-octadecadienamide (Mm). Further analyses revealed that the key microbes metabolizing Mm belonged to Alistipes, Alloprevotella, Parabacteroides, and Butyricimonas genera and the Prevotellaceae in mice. The results of microbial analysis showed that Mm could improve exercise-induced skeletal muscle fatigue in mice by modulating the L-glutamate–ornithine–proline axis through the breakdown of histidine, arginine, and proline. Therefore, from foodomics and gut microbial genomics perspectives, this study demonstrates that macamide is the key anti-fatigue component in maca, and these findings provide new insights for the development of foods that fight fatigue.

Graded Compression Garments Worn During Resistance Exercise: Impact on Muscle Damage, Fatigue, and Oxygenation in Untrained Individuals

Background: Use of compression garments during and after exercise has gained notable popularity, yet their utility in augmenting performance and recovery from resistance exercise remains elusive. Objective: The purpose of this study was to evaluate the effects of wearing compression garments during resistance exercise on exercise-induced muscle damage (EIMD), muscle fatigue and muscle oxygenation. Methods: Ten healthy, untrained individuals (8 females, 2 males, 22.10 ± 2.23 years, 159.09 ± 3.47 cm, 66.22 ±15.93 kg; mean ± SD) performed two exercise trials in a randomized crossover (within-subject) design: 1) with compression garments worn on the legs and 2) without compression. Exercise trials were randomized and separated by seven days. Participants performed 12 sets of 10 maximal repetitions of knee extension, at a velocity of 120 degrees per second, in the CON/ECC mode of a HUMAC NORM isokinetic dynamometer. Muscle oxygenation of the vastus medialis oblique was assessed using time-resolved near-infrared spectroscopy (TRS-21, Hamamatsu). Leg circumference, ratings of perceived muscle soreness (RPMS) and blood samples for creatine kinase (CK) were collected before, immediately after, and 24, 48 and 72 hours after exercise. Results: Total hemoglobin (p = 0.021) and deoxyhemoglobin (p 0.001) were significantly reduced by 8.6% and 9.2% respectively with compression compared to control. No significant differences were found in oxyhemoglobin, oxygen saturation, muscle fatigue, leg circumference, RPMS and CK (p = 0.0791) between conditions. Conclusions: Although lower body compression worn during resistance exercise reduced total hemoglobin and deoxyhemoglobin, there was no impact on muscle fatigue, RPMS, leg circumference or CK.

Effects of compression garment on muscular efficacy, proprioception, and recovery after exercise-induced muscle fatigue onset for people who exercise regularly.

Fatigue is a major cause of exercise-induced muscle damage (EIMD). Compression garments (CGs) can aid post-exercise recovery, therefore, this study explored the effects of CGs on muscular efficacy, proprioception, and recovery after exercise-induced muscle fatigue in people who exercise regularly. Twelve healthy participants who exercised regularly were enrolled in this study. Each participant completed an exercise-induced muscle fatigue test while wearing a randomly assigned lower-body CG or sports pants (SP); after at least 7 days, the participant repeated the test while wearing the other garment. The dependent variables were muscle efficacy, proprioception (displacements of center of pressure/COP, and absolute error), and fatigue recovery (muscle oxygen saturation/SmO2, deoxygenation and reoxygenation rate, and subjective muscle soreness). A two-way repeated measure analysis of variance was conducted to determine the effect of garment type. The results indicated that relative to SP use, CG use can promote muscle efficacy, proprioception in ML displacement of COP, and fatigue recovery. Higher deoxygenation and reoxygenation rates were observed with CG use than with SP use. For CG use, SmO2 quickly returned to baseline value after 10 min of rest and was maintained at a high level until after 1 h of rest, whereas for SP use, SmO2 increased with time after fatigue onset. ML displacement of COP quickly returned to baseline value after 10 min of rest and subsequently decreased until after 1 hour of rest. Relative to SP use, CG use was associated with a significantly lower ML displacement after 20 min of rest. In conclusion, proprioception and SmO2 recovery was achieved after 10 min of rest; however, at least 24 h may be required for recovery pertaining to muscle efficacy and soreness regardless of CG or SP use.

Effect of Topical Sports Cream Containing Cymbopogon schoenanthus on Acute Recovery Markers Following Exercise-Induced Muscle Fatigue in Competitive Athletes: A Pilot Study

Background: Muscle fatigue following high-intensity or repetitive training causes reduced muscle strength, restriction of blood flow, and increased muscle pain. The application of topical sports cream (TSC) as a recovery method has recently gained attention. However, few studies have investigated the effects of topical sports cream containing Cymbopogon schoenanthus (CS) on acute recovery markers. This study aimed to examine the effects of the acute application of a TSC containing CS after exercise-induced muscle fatigue on acute recovery markers. Methods: Ten taekwondo athletes (male: 5, female: 5) participated in this study. In a crossover design with 2-week intervals, participants were randomly assigned to two clinical trial groups: TSC and placebo cream (PC). Isokinetic dynamometers were used to create exercise-induced muscle fatigue, and the subjects repeatedly performed external and internal shoulder rotations. TSC containing CS was applied to the shoulder muscles of the subjects after the exercise. Maximum voluntary isometric contraction, muscle pain, blood flow, and skin temperature were measured before, during, immediately after, 30 min after, and 60 min after exercise. Results: A significant interaction effect was found in blood flow between time and group (p = 0.032, ηp2 = 0.157). However, there was no statistically significant interaction effect between time and group for maximum voluntary isometric contraction (MVIC), muscle pain, and skin temperature (p &gt; 0.05). Conclusions: Acute application of TSC containing CS is effective in increasing blood flow during the recovery period following exercise-induced muscle fatigue.

Effect of sex and fatigue on quiet standing and dynamic balance and lower extremity muscle stiffness.

The purpose of the present study was to determine whether there are sex differences in fatigue-induced changes in quiet standing and dynamic balance and establish whether changes in muscle torque and resting stiffness may explain the potential sex differences in balance responses. Sixteen recreationally active men (age; 24.8 ± 5.0years, height; 178.2 ± 5.6cm, mass; 77.8 ± 13.2kg) and 10 women (age; 21.0 ± 1.6years, height; 167 ± 5.3cm, mass; 61.3 ± 8.9kg) were assessed for postural sway, Y balance test performance, isokinetic and isometric knee extensor torque and resting stiffness of the vastus lateralis (VL), gastrocnemius lateralis (GL) and Achilles tendon (AT) before and immediately after fatiguing exercise. The fatigue protocol consisted of five sets of 20-drop jumps. The fatiguing exercise elicited similar magnitude (effects size; ES) reductions in muscle torque (men; ES = 0.45-0.80, women; ES = 0.46-0.52), dynamic balance (men; ES = 0.45-0.74, women; ES = 0.47-0.79) and resting VL stiffness (men; ES = 0.46, women; ES = 0.36) in men and women (all p < 0.05). For quiet standing balance, fatigue induced an increase in postural sway metrics (ES = 0.64-1.28) and reduction in resting GL stiffness (ES = 0.40) in men (both p < 0.001) but not women (p > 0.05). Fatiguing exercise, when producing a similar level of force reduction, induces similar magnitude reductions in dynamic postural control and resting VL stiffness in men and women. Distinct deteriorations in quiet standing balance in men but not women were accompanied by modifications in calf muscle stiffness following exercise-induced muscle fatigue.

Effect of glutathione supplementation on swimmers’ performance

Background and Study Aim. Continuously increasing the volume and intensity of the training sessions often leads to overtraining. It has been demonstrated that glutathione supplementation might improve the aerobic metabolism in skeletal muscle and reduce exercise-induced muscle fatigue. The aim of the study was to assess the effect of glutathione supplementation on fatigue, recovery processes, and competitive results of elite swimmers during a six-week training period.&#x0D; Material and Methods. Twenty-four elite swimmers (10 women and 14 men) from the Bulgarian national swimming team, with a mean age of 18.7±3.78 years, took part in this double-blind placebo control study. The swimmers from the experimental group were supplemented once a day with a capsule of 250mg glutathione, whilst the swimmers from the control group took a placebo once a day. The urine concentration levels of cortisol and cortisone, as well as the degree of overtraining, were evaluated on the 1st(T1), 14th(T2), 28th(T3), and 42nd(T4) days. Anthropometric measurements and a nutritional assessment were performed at T1 and T4.&#x0D; Results. The swimmers showed a gradual decrease of cortisol and cortisone during the study, with significantly lower concentrations in the experimental vs the control group at T4 (19.4 vs 42.5 ng/mL, p &lt; 0.05). At the end of the study, the swimmers from the experimental group showed improvements in their time in 41 out of the 43 swimming events, whilst those from the control group had significantly smaller improvements (-1.66 vs -0.97%, p &lt; 0.05).&#x0D; Conclusions. In conclusion, glutathione supplementation at a dose of 250mg/day for six weeks improves the adaptation of elite swimmers towards training schedules, which is likely to lead to better sports results.

Serum Cardiac and Skeletal Muscle Marker Changes in Repetitive Breath-hold Diving

BackgroundBreath-hold diving (BH-diving) is associated to extreme environmental conditions, prolonged physical activity, and complex adaptation mechanisms to supply enough O2 to vital organs. Consequently, one of the biggest effects could be an increased exercise-induced muscle fatigue, in both skeletal and cardiac muscles that can induce an increase of muscles injury markers including creatine kinase (CK), aspartate transferase (AST), and alanine transferase (ALT) when concerning the skeletal muscle, cardiac creatine kinase isoenzyme (CK-MBm) and cardiac troponin I (cTnI) when concerning the cardiac muscle, and lactate dehydrogenase (LDH) as index of muscle stress. The aim of this study is to investigate serum cardiac and skeletal muscle markers before and after a BH-diving training session.ResultsWe found statistically significant increases of CK (T0: 136.1% p < 0.0001; T1: 138.5%, p < 0.0001), CK-MBm (T0: 145.1%, p < 0.0001; T1: 153.2%, p < 0.0001) LDH (T0: 110.4%, p < 0.0003; T1: 110.1%, p < 0.0013) in both T0 and T1 blood samples, as compared to basal value. AST showed a statistically significant increase only at T0 (106.8%, p < 0.0007) while ALT did not exhibit statistically significant changes. We did not find any changes in cTnI levels between pre-dive and post-dive samples.ConclusionsOur data seem to indicate that during a BH-diving training session, skeletal and cardiac muscles react to physical effort releasing stress-related substances. Although the peculiar nature of BH-diving makes it difficult to understand if our results are related only to exercise induced muscle adaptation or whether acute hypoxia or a response to environmental changes (pressure) play a role to explain the observed changes, further studies are needed to better understand if these biomarker changes are linked to physical exercise or to acute hypoxia, or if both conditions play a role.

EFFECT OF CHINESE MEDICINE ON MUSCLE FATIGUE OF ATHLETES

ABSTRACT Introduction: Traditional Chinese medicine has a very good effect on the treatment of exercise fatigue. However, if it is not handled actively and effectively, it can cause serious adverse effects on the body and lead to many diseases. Objective: To study the effect of TCM diagnosis and treatment on athletes’ exercise-induced muscle fatigue. Methods: The results of the study were analyzed by comparing the experimental data in the experimental group and the control group. Results: A paired t test was conducted on the experimental results of the experimental intervention group and the data of the control group. It was found that regardless of individuals being male or female, the paired t test results of the experimental group and the data of the control group were all P &lt; 0.05, showing significant differences in the paired data. Conclusions: In the experiment, all the treatment methods of traditional Chinese medicine had an obvious effect in the treatment of exercise fatigue, and reduced the recovery time of exercise fatigue at different degrees. Contrastive analysis shows that traditional Chinese medicine is effective in the treatment of exercise fatigue. Level of evidence II; Therapeutic studies - investigation of treatment results.

Muscle Strength and Power: Primary Outcome Measures to Assess Cold Water Immersion Efficacy After Exercise With a Strong Strength or Power Component.

Recovery from exercise-induced muscle damage, fatigue or stress is critical for restoration of exercise performance. In most exercise activities or sports, performance is regulated through the physiological capacity of muscle. Therefore, athletes, coaches, and scientists have continued to explore post-exercise recovery modalities that focus on expediting muscle functional recovery. Several post-exercise recovery strategies have been developed, tested, and used in amateur and professional athletes to expedite muscle functional recovery. A cost-effective and well-researched practice to achieve this goal is cold water immersion (CWI). CWI requires submersion of a limb or the whole body in cold water of a specified temperature (usually <15°C) for a specified duration immediately post-exercise, or over several succeeding days. However, the equivocal findings on the efficacy of CWI and the extensive number of outcome variables has made it challenging to interpret and correctly implement this intervention. In this short opinion piece, we briefly review CWI research and the challenges that practitioners and athletes face when deciding whether to use CWI as a post-exercise recovery intervention. We then discuss why muscle strength and/or power should be considered the primary outcome variable in CWI research with a strong strength and power component, and why excitation–contraction coupling and/or rate of force development assessment is necessary to evaluate strength/power-specific changes. Finally, we present systematic evidence that there is a dearth of strength measurements in CWI research, which could be limiting our understanding of this post-exercise recovery strategy.