Search Results (260)

Background: Durative exercise-induced fatigue influences muscle structure and exercise performance. Dietary supplements combining bioavailable proteins with essential vitamins and minerals may help reduce fatigue. Compared with proteins, whey peptides, as easily absorbed energy sources, are regarded as better promoting the utilization of vitamins and minerals. This study investigated whether the combination of whey peptides and micronutrients could synergistically improve exercise-induced fatigue and exercise performance. Methods: Four-week-old male C57BL/6J mice were forced to exercise using a treadmill for four weeks to evaluate the supplemental effects of whey peptides and/or micronutrients on exercise performance. Results: Compared with mice receiving whey peptides or micronutrients alone, mice receiving a combination of whey peptides and micronutrients displayed increased muscle mass, muscle fiber cross-sectional area, muscle strength, and exercise performance, including running exhausting time and swimming exhausting time. Consistent results were obtained in detecting fatigue-associated serum metabolites and markers reflecting muscle injury. To elucidate the anti-fatigue mechanisms of whey peptides and micronutrients, RNA transcriptome in the muscle tissues were analyzed. Enrichment analysis results suggest that micronutrients and/or whey protein alleviate exercise-induced fatigue, not only via reducing oxidative stress but also repressing excessive immune activation in muscle tissue, thereby decreasing the tissue injury caused by strenuous exercise. Conclusions: Overall, the current study indicates that the combination of whey peptides and micronutrients produces a synergistic effect on promoting exercise performance. Our findings provide scientific evidence for the development of novel and efficient anti-fatigue functional foods using whey peptides and micronutrients. Full article

Background: Acute alterations in biomechanical and viscoelastic muscle properties provide important insight into early fatigue mechanisms; however, their dependence on specific muscle contraction types remains insufficiently understood. Therefore, the aim of this study was to quantitatively compare the acute effects of eccentric, concentric, isometric, and mixed contractions on the biomechanical and viscoelastic properties of the biceps brachii using myotonometry. Methods: Eighty healthy men aged 40 to 50 years were randomly assigned to four contraction conditions: eccentric, concentric, isometric or mixed concentric-eccentric. Each participant performed four sets of isolated biceps brachii exercise to volitional failure. Myotonometric measurements of tone, stiffness, decrement, relaxation and creep were collected before exercise and after each set. Changes within and between contraction types were analyzed. Results: Muscle responses differed significantly depending on contraction type. Dynamic contractions induced immediate viscoelastic changes, with significant reductions in relaxation time after eccentric (p = 0.027), concentric (p = 0.026), and mixed contractions (p < 0.001), while no changes were observed after isometric contraction (p = 0.285). Stiffness remained stable across all contraction types (p > 0.05). Mixed contractions showed a biphasic response in decrement with a significant effect across series (p = 0.049), identifying decrement as the most sensitive indicator of early fatigue, whereas isometric contraction produced no significant modifications in any parameter. Conclusions: Dynamic muscle work induces rapid and contraction-dependent shifts in viscoelastic properties, whereas stiffness appears resistant to short-term loading. Isometric contractions display minimal mechanical disturbance. Myotonometry proved effective in detecting early fatigue-related changes and decrement may serve as a key marker of short-term muscle adaptation. Full article

Background: Inter-limb asymmetry has implications for both athletic performance and healthcare practice. High baseline inter-limb asymmetries have been associated with impaired mobility, increased fall risk, and musculoskeletal injuries across the lifespan. Exercise interventions able to stimulate the stretch–shortening cycle (e.g., plyometric training and jump training) have been shown to have a good impact on asymmetries. Among these, Mini-Trampoline Training (MTT) has recently emerged as potentially effective in reducing asymmetries. Objectives: The study aimed to evaluate the acute effects of a single MTT session on muscle power and inter-limb asymmetry in young adults. Methods: Twenty-eight recreationally active participants (25.6 ± 2.4 years) completed one MTT session. Before (PRE) and after (POST) the MTT session, single-leg 6 m Timed Hop (6MTH) and countermovement jump (CMJ) tests were administered. Additionally, 6MTH values of the dominant (DOM) and non-dominant (NODOM) limbs were used to stratify participants according to higher (HBIA) or lower (LBIA) baseline inter-limb asymmetry, based on a commonly adopted Normalized Symmetry Index (NSI) threshold (NSI ≥ 10%, n = 12; NSI < 10%, n = 16). Repeated-measures mixed models were used to evaluate the effects of the MTT session on 6MTH, NSI, and CMJ. Results: Regardless of group and limb, significant (p < 0.0001) improvements in 6MTH (PRE: 2.5 ± 0.06 s; POST: 2.3 ± 0.05 s) were found. Interestingly, the MTT session had a significant (p = 0.01) effect on both groups, with a significant (p = 0.003) interaction with NSI values, showing an improvement for HBIA (PRE = 15.4 ± 1.1%, POST = 11.3 ± 2.1%), whereas a decrement in LBIA was recorded (PRE = 5.1 ± 0.6%, POST = 9.6 ± 1.5%). CMJ did not show any changes in HBIA (PRE: 36.2 ± 0.9 cm; POST: 35.1 ± 0.7 cm), while a significant (p = 0.007) decrease was found in LBIA (PRE: 34.8 ± 1.2 cm; POST: 33.2 ± 1.3 cm). Conclusions: A single MTT session induced acute neuromuscular fatigue, reflected by reduced CMJ performance and improved (~8%) inter-limb control during hopping. The HBIA group preserved jump height (~36 cm) and demonstrated a significant reduction in asymmetry (NSI: −4.1%), suggesting more balanced lower-limb recruitment. Conversely, LBIA showed a significant decrease in CMJ and an increased NSI (+4.5%), possibly reflecting fatigue-related compensatory strategies. Overall, a single MTT elicited distinct responses according to baseline asymmetry, supporting its potential as an adaptable modality for enhancing neuromuscular function in HBIA. Full article

Background/Objectives: Recent preclinical studies suggest that acute exercise induces immune modulation, enhances tumor blood perfusion, and is associated with reduced tumor growth. Adding exercise to immunochemotherapy treatment (ICT) has been proposed as a strategy to increase treatment effectiveness. The ERICA trial (NCT04676009) aimed to assess the feasibility of acute aerobic exercise performed immediately before the administration of ICT in patients with metastatic non-small cell lung cancer (mNSCLC) and to explore hypothesis-generating outcomes related to physical fitness and patient-reported outcomes. Methods: Newly diagnosed mNSCLC patients were randomly assigned (2:1) to the exercise or control group. The exercise intervention included supervised acute exercise before each of four ICT cycles plus a 3-month home-based walking program with an activity tracker and step goals. The feasibility of the exercise protocol was assessed through adherence, acceptability, tolerability, and safety. Clinical, physical, and patient-reported outcomes were assessed at baseline and after 3 months. Results: Twenty-six patients (mean age 60.6 years; SD 10.65) participated, with an 87.5% acceptance rate. In the exercise group (n = 17), 80.9% of participants completed the acute exercise sessions, with a median interval of 38 min [IQR, 20–60] between exercise and ICT. No exercise-related adverse effects were reported. After 3 months, 60% of participants in the exercise group were classified as active and maintained their step goals. Self-reported measures suggest that maintaining physical fitness is favorable for reducing fatigue and insomnia, and therefore improving quality of life. Conclusions: Acute exercise performed immediately before each ICT administration in patients with mNSCLC appears feasible and safe. Full article

Exercise-induced fatigue involves oxidative stress and metabolic dysregulation. While the anti-aging protein α-Klotho regulates metabolism and oxidative stress, its role in exercise fatigue is unexplored. This study investigated whether α-Klotho supplementation mitigates cumulative exercise-induced fatigue and elucidated the underlying tissue-specific mechanisms. Male C57BL/6J mice were divided into three groups (n = 10 per group), the control group, fatigue treated with saline, or α-Klotho (0.2 mg/kg, i.p. daily) group. Fatigue was induced by a 6-day exhaustive swimming protocol (5% body weight load). Tissues were collected 24h post-final exercise. Assessments included daily exhaustion time, grip strength, serum creatine kinase (CK), urea nitrogen (BUN), oxidative stress markers (H₂O₂, MDA, SOD, GSH/GSSG), tissue glycogen, and pathway protein expression (Western blot). α-Klotho supplementation prevented exercise-induced weight loss and restored grip strength. While exhaustive exercise markedly increased serum CK and BUN levels, α-Klotho selectively normalized CK without effecting serum BUN. α-Klotho attenuated oxidative damage by reducing hydrogen peroxide levels while enhancing antioxidant capacity, accompanied by activation of the NRF2/HO-1 pathway and further upregulation of PGC-1α. Notably, α-Klotho induced striking hepatic glycogen supercompensation through activation of the AKT/GS signaling pathway and upregulation of GLUT4, whereas muscle glycogen levels remained unchanged. In conclusion, α-Klotho ameliorates cumulative exercise-induced fatigue through dual recovery-phase mechanisms: NRF2/HO-1-mediated antioxidant protection in skeletal muscle and AKT/GS-triggered hepatic glycogen supercompensation, thereby facilitating oxidative stress resolution and enhancing energy reserve restoration. Full article

Major depressive disorder is increasingly recognized as a metabolic–immune disorder in which chronic inflammation diverts tryptophan (Trp) metabolism toward the kynurenine pathway (KP), reducing serotonin synthesis and producing neurotoxic metabolites such as quinolinic acid (QA). Elevated kynurenine (KYN)/Trp ratios and an altered QA/kynurenic acid (KYNA) balance have been consistently reported in depressed individuals, implicating the KP as a key therapeutic target. Exercise provides a unique, translationally relevant intervention: unlike pharmacological agents acting directly on neurotransmission, contracting skeletal muscle acts as a “kynurenine sink” by inducing kynurenine aminotransferases that convert circulating KYN into neuroprotective KYNA, thereby reducing brain KYN uptake and mitigating excitotoxicity. Clinical studies and meta-analyses confirm that aerobic, resistance, and high-intensity training produce antidepressant effects comparable to pharmacotherapy, while also improving cognition, fatigue tolerance, and cardiometabolic function. Beyond KP remodeling, exercise-induced myokines (irisin, IL-6, BDNF, apelin, FGF21) and adipokines (adiponectin, leptin modulators) coordinate systemic anti-inflammatory and neurotrophic adaptations that enhance resilience and brain plasticity. Furthermore, pharmacological “exercise mimetics” and metabolic modulators, such as PPAR agonists, AMPK activators, NAD⁺ boosters, meldonium, trimetazidine, and adiponectin receptor agonists, may be promising adjuncts for patients with low exercise capacity or metabolic comorbidities. This review provides a novel concept, positioning exercise as a systemic antidepressant that breaks the kynurenine lock of depression. Through proper interpretation of skeletal muscle as an endocrine organ of resilience, we integrate molecular, clinical, and translational findings to show how exercise remodels Trp–KYN metabolism and inflammatory signaling and how pharmacological mimetics may extend these benefits. This perspective consolidates scattered mechanistic and clinical data and outlines a forward-looking therapeutic framework that links exercise and lifestyle, metabolism, and drug discovery. We highlight that re-consideration of our understanding of depression, as a whole-body disorder, should provide new opportunities for precision interventions. Full article

This investigation employed a between-participant design comparing acute and chronic changes in brain-derived neurotrophic factor (BDNF), cathepsin B (CatB), insulin-like growth factor-1 (IGF-1), and interleukin-6 (IL-6) across four resistance training (RT) protocols differing in proximity to failure, while also examining inter-biomarker correlations. Thirty-eight resistance-trained men completed an eight-week intervention, training three times per week, allocated to one of four groups based on repetitions-in-reserve (RIR): 4–6 RIR, 1–3 RIR, 0–3 RIR, and 0 RIR. Serum was collected immediately before and after training on day 1 of weeks 1 and 7. The analysis revealed the main effects of Session for BDNF and IL-6 (posterior probability > 99%), indicating exercise-induced elevation independent of proximity to failure. Additionally, CatB demonstrated a Session × Week interaction (posterior probability > 99%), indicating a difference in the acute response between week 7 and week 1. No compelling evidence emerged for IGF-1 effects, and inter-biomarker correlations were weak and inconsistent. Notably, this is the first investigation to demonstrate RT-induced transient CatB elevation. These findings suggest that exercise-induced neuroprotective biomarker responses may be achieved while training relatively far from failure, potentially avoiding the neuromuscular fatigue, injury risk, and recovery demands associated with failure training. Full article

This study aimed to investigate the effects of acute exhaustion exercise on cognitive control in young men, a key higher cognitive function for goal-directed behavior. Although long-term regular exercise benefits cognition, the effects of acute exhaustion exercise on cognitive control and its neural mechanisms are not fully understood. 35 male college students completed a Stroop task before and after exhaustion exercise on a cycle ergometer with incremental load. Electroencephalogram data were collected synchronously during the task. Behavioral measures (accuracy, reaction time), Event-Related Potential components (N2, P3 amplitudes and latencies), and Event-Related Spectral Perturbation (energy changes in theta, alpha, beta frequency bands) were analyzed. Results: Behavioral results showed that task accuracy only significantly decreased under the conflict condition (incongruent trials) following exhaustive exercise. ERP analysis revealed that the P3 amplitude at the anterior site (Fz) was significantly reduced post-exercise, but specifically for the incongruent condition, while the N2 amplitude demonstrated a more widespread enhancement. Time–frequency analysis found a significant decrease in alpha-band power over the parietal region after exercise. Theta and beta band activities were not significantly affected by exercise-induced fatigue. Conclusions: Acute exhaustive exercise did not impair early conflict monitoring functions (as indicated by stable N2 component and theta oscillations), but it compromised later higher-order cognitive processes related to attentional resource allocation and conflict resolution (manifested as reduced anterior P3 amplitude), accompanied by decreased efficiency in neural oscillatory activity associated with inhibitory control (reduced alpha power). This suggests that fatigue primarily affects the neural mechanisms of the “implementation” stage rather than the “monitoring” stage in the cognitive control cascade. Full article

Background: Exposure to hypoxia is widely used to enhance training adaptations, but its acute effects on cardiac function remain unclear. Exercise-induced cardiac fatigue (EICF), defined as transient impairments in left ventricular (LV) systolic and diastolic function, has been reported after endurance exercise. Whether moderate hypoxia influences EICF, particularly in athletes, is unknown. Methods: Twenty-four healthy men participated: 12 endurance-trained cyclists (T) and 12 untrained individuals (UT). Each completed two exhaustive cycling tests under normoxia (FiO₂ = 20.9%) and moderate normobaric hypoxia (FiO₂ = 14.4%; ~3000 m). Echocardiography was performed at rest and immediately post-exercise to assess LV systolic and diastolic function. Results: Exhaustive exercise reduced LV diastolic function in both groups, with no significant condition-related differences. Under normoxia, early peak filling velocity (Mitral E) decreased by 21.2% in UT and 23.2% in T, and under hypoxia, by 16.2% in UT and 14.9% in T. Global longitudinal strain (LV GLS) became less negative after exercise under normoxia (UT: +25.2%, T: +30.6%) and hypoxia (UT: +24.8%, T: +20.3%). Athletes exhibited slightly less post-exercise systolic impairment under hypoxia than normoxia, reflected by the maintenance of a more negative LV GLS (∆GLS: 6.87 ± 2.65% in normoxia vs. 4.55 ± 1.86% in hypoxia, p < 0.05). Conclusions: Moderate normobaric hypoxia (~3000 m) did not exacerbate EICF in either group. Athletes showed slightly less post-exercise systolic impairment under hypoxia. Moderate hypoxia may modify the cardiac response to exhaustive exercise, but studies with larger samples and direct preload assessment are needed. Full article

Background: Left ventricular (LV) mechanics assessed by speckle-tracking echocardiography provides sensitive markers of cardiac adaptation to exercise. Different training modalities—endurance, high-intensity interval training (HIIT), and acute exercise tests—impose distinct hemodynamic loads, yet their comparative effects on LV deformation remain unclear. Importantly, acute and chronic endurance exposures may elicit divergent myocardial responses that must be interpreted separately. Methods: A systematic search of PubMed, Scopus, and EMBASE (through September 2025) identified studies evaluating LV mechanics in response to endurance, HIIT, or acute exercise among healthy or recreationally active individuals. Echocardiographic parameters of strain and torsion were extracted, and methodological quality was appraised using the NIH Quality Assessment Tool. Results: Twenty-three studies (859 participants) met inclusion criteria. Acute prolonged endurance exercise—particularly marathon and ultra-endurance events—was associated with transient, fully reversible reductions in global longitudinal, circumferential, and radial strain and torsion, despite preserved ejection fraction, reflecting short-term myocardial fatigue rather than maladaptive remodeling. In contrast, chronic endurance training maintained or improved LV mechanics without evidence of dysfunction, while HIIT interventions consistently enhanced LV systolic strain and rotational indices across diverse age groups and sexes, reflecting improved contractile efficiency and physiological remodeling. Acute exercise produced heterogeneous, load-dependent strain responses, with isometric stress increasing regional strain and maximal exertion inducing temporary global reductions. Between-study heterogeneity was moderate, methodological quality generally good, and small-study effects varied by modality, being most evident in endurance studies, borderline for HIIT, and limited for acute tests due to sample size. Conclusions: Acute endurance exercise produces transient, reversible LV deformation changes, whereas chronic endurance training preserves mechanical efficiency. HIIT reliably enhances systolic strain and torsional mechanics, and acute exercise elicits variable but physiologically meaningful responses. These findings clarify that transient post-race strain reductions reflect physiological fatigue, not chronic maladaptation, and underscore the modality-specific nature of myocardial adaptation to exercise. Full article

The conventional deadlift is frequently performed in multiple-repetition sets at loads exceeding 80% of one-repetition maximum (RM) to increase maximal strength in the posterior chain. Fatigue-induced intra-set movement alterations have been observed in various exercises and loading ranges, but whether they occur under strength-specific deadlift conditions remains poorly understood. This study compared the intra-set development of spinal and lower extremity kinematics, net joint moments (NJMs) of the lower extremities, and surface electromyography (sEMG) amplitudes during a 3RM deadlift using statistical parametric mapping. Ten strength-trained women (body mass: 69.2 ± 8.1 kg, height: 166.3 ± 3.1 cm, age: 23.2 ± 3.7 years) lifted 100.6 ± 18.1 kg for a set of 3RM deadlifts. Across repetitions, spinal flexion and hip extension angles increased, while barbell velocity and peak angular hip extension velocity decreased. In contrast, hip NJMs and sEMG amplitudes showed minimal or no significant differences between repetitions. These findings suggest that as fatigue accumulates during a 3RM set, lifting capacity is maintained primarily through kinematic adjustments rather than increased hip extensor contribution. Full article

Subjects with low back pain (LBP) have shown different responses to fatigue compared to healthy individuals. The aim of this study was to analyze and compare the connectivity of the multifidus muscles using intermuscular coherence (IMC) in a squat protocol between healthy subjects and a subject with a history of low back pain. The protocol consisted of three sets of squats, with the final set performed with as many repetitions as possible to induce muscular fatigue. The findings indicated that IMC decreased among healthy subjects during the last repetitions of the squat series, with percentage changes in connectivity (CC) ranging from approximately 43.3% to 67.3% when comparing the first and last 10 repetitions. In contrast, the subject with a history of low back pain (LBP) exhibited an opposite trend, showing a 41.8% increase in IMC. These results suggest a different response of IMC to fatigue related to LBP. This also establishes IMC as a potentially useful tool for characterizing fatigue and LBP during physical exercise. Full article

Muscle fatigue, defined as a decline in force generation, is closely linked to redox imbalance—a condition exacerbated by oxidative stress in hypertension. This study investigated the effects of diazoxide administration and moderate-intensity exercise on skeletal muscle redox status following a fatigue protocol in rats with hypertension. Animals were assigned to eight groups: control (CTRL), diazoxide (DZX), exercise (EX), exercise + diazoxide (EX+DZX), hypertension (HTN), hypertension + diazoxide (HTN+DZX), hypertension + exercise (HTN+EX), and hypertension + exercise + diazoxide (HTN+ EX+DZX). Hypertension was induced by a high-salt diet. Diazoxide was administered daily for 14 days, and exercise consisted of moderate treadmill running for 8 weeks. Muscle fatigue was evoked in the extensor digitorum longus (EDL) and soleus by repetitive electrical stimulation. Post-fatigue analyses included oxidant levels, catalase activity, and glutathione status. Hypertension increased oxidants and reduced antioxidant defenses in both muscle types. Exercise and diazoxide, alone or in combination, improved redox balance, with the combined treatment providing the most robust protection and exhibiting fiber-specific adaptations. These findings suggest that diazoxide combined with moderate exercise represents a promising therapeutic approach to counteract oxidative stress-related skeletal muscle dysfunction in hypertension. Full article

Monitoring exercise-induced fatigue is important for maintaining the effectiveness of training and preventing injury. We evaluated a non-contact approach that estimates perceived fatigue from full-body kinematics captured by an Azure Kinect depth camera. Ten healthy young adults repeatedly performed simple, reproducible whole-body movements, and 3D skeletal coordinates from 32 joints were recorded. After smoothing, 24 kinematic features (joint angles, angular velocities, and cycle timing) were extracted. Fatigue labels (Low, Medium, and High) were obtained using the Borg CR10 scale at 30-s intervals. A random forest classifier was trained and evaluated with leave-one-subject-out cross-validation, and class imbalance was addressed by comparing no correction, class weighting, and random oversampling within the training folds. The model discriminated fatigue levels with high performance (overall accuracy 86%; macro ROC AUC 0.98 (LOSO point estimate) under oversampling), and feature importance analysis indicated distributed contributions across feature categories. These results suggest that simple camera-based kinematic analysis can feasibly estimate perceived fatigue during basic movements. Future work will expand the cohort, diversify tasks, and integrate physiological signals to improve generalization and provide segment-level interpretability. Full article

Light therapy has been shown to produce several beneficial physiological effects in a wide range of tissues. The musculoskeletal system can be irradiated with deeply penetrating wavelengths in near infrared (NIR) regions. Photobiomodulation therapy (PBMT) reduces pain and inflammation and enhances physical performance. However, the mechanism(s) of cellular responses to PBMT in muscle is not clearly understood. Therefore, the goal of this study is to improve our understanding of the mechanism(s) of action of PBMT effects in exercised and sedentary muscle. In sedentary mice, PBMT using a wavelength of 830 nm increased the gene expression for muscle tissue development, including cFos, which is critical for activating interstitial and satellite cells that repair muscle. Immunostaining for cFOS expression confirmed an increase in the number of activated cells in PBMT-treated muscle. We observed that PBMT-treated mice showed increased performance on the treadmill, reduced muscle fiber damage, and altered mitochondrial structure. RNA sequencing from fatigued TA tissue suggested that PBMT treatment increased the gene expression of tissue regeneration and remodeling, suggesting tissue adaptation and muscle repair after exercise with PBMT. In conclusion, our study suggests that the 830 nm wavelength may have altered the muscle by activating regenerative genes that protect the tissue from exercise-induced cellular stress. Full article