Search Results (754)

Background/Objectives: The evidence for nutritional interventions against fatigue is limited; we evaluated whether L-arginine reduces fatigue in working-age adults. Methods: In this 8-week randomized, double-blind, placebo-controlled trial, 120 community-dwelling working-age adults aged 30–59 years with persistent fatigue (Fatigue Severity Scale [FSS] total ≥ 27) received oral L-arginine 3 g/day, 6 g/day, or placebo. The primary endpoint was FSS change; secondary endpoints included the Checklist Individual Strength (CIS), Pittsburgh Sleep Quality Index (PSQI), and blood lactate kinetics during a standardized submaximal treadmill run (~70% VO₂max, 30 min). Data from 119 participants were analyzed, with Holm adjustment for multiplicity. Results: At Week 8, FSS decreased more with 6 g/day than with placebo (−6.41 vs. −2.23; Holm-adjusted p = 0.024), whereas 3 g/day did not differ from placebo. The 6 g/day CIS improvement did not survive multiplicity adjustment. PSQI scores improved nominally at both doses (3 g/day, p = 0.007; 6 g/day, p = 0.045). With 6 g/day, the total lactate area under the curve (Holm-adjusted p = 0.041) and 15-min recovery lactate (Holm-adjusted p = 0.002) were lower than with the placebo, whereas the resting plasma nitrite did not differ. No serious adverse events occurred. Conclusions: L-arginine supplementation at 6 g/day for 8 weeks reduced fatigue severity relative to placebo and was well-tolerated; however, mean FSS scores remained above the enrollment threshold, indicating a reduction in, rather than resolution of, persistent fatigue. Full article

Background/Objectives: Musculoskeletal pain and balance impairments are common in patients referred for cardiac rehabilitation (CR), but their influence on early exercise participation and aerobic capacity remains unclear. This study examined whether pain and muscle mass are associated with initial exercise tolerance test (ETT) participation and VO₂ peak. Methods: This retrospective, single-center cohort included 162 of 189 patients referred to CR after percutaneous coronary intervention for acute myocardial infarction; 105 who completed a symptom-limited cardiopulmonary exercise test were analyzed for VO₂ peak. Pain intensity was assessed using a visual analog scale (VAS 0–10), and the skeletal muscle index (SMI) was measured using a bioelectrical impedance analysis. Determinants of ETT participation and VO₂ peak were evaluated using multivariable logistic and linear regressions, respectively, with pain analyzed as a binary, three-category, and continuous variable. Results: More than half the patients reported musculoskeletal pain during physical activity, and 24.7% had balance problems. Patients with pain (VAS 1–10) had lower appendicular skeletal muscle mass and poorer functional status than pain-free patients. Among the 105 who completed the ETT, the pain group showed significantly lower workload-estimated metabolic equivalents [METs (Q)], respiratory exchange ratios, and peak minute ventilation and a shorter exercise time, but VO₂ peak did not differ between the groups. ETT participation rates were similar across pain categories (63.4%, 67.2%, and 63.0% for VAS 0, 1–5, and 6–10, respectively). In the multivariable logistic regression, older age, hypertension, and low SMI scores were independently associated with reduced ETT participation. In the linear regression, age was the only significant predictor of VO₂ peak; the SMI score showed a borderline association (p = 0.065), but pain intensity was not independently associated with VO₂ peak. Conclusions: Musculoskeletal pain is prevalent among patients entering CR after myocardial infarction, and it is accompanied by low muscle mass and functional limitations. However, after adjustment, pain itself was not an independent determinant of ETT participation or VO₂ peak. Low SMI scores were independently associated with reduced test participation and showed only a borderline association with aerobic capacity. These cross-sectional findings should be regarded as hypothesis-generating. Full article

Mitochondrial-derived peptide MOTS-c is an exercise-responsive mitokine, yet its associations with exercise capacity and antioxidant markers remain unclear. This cross-sectional study examined serum MOTS-c across three stratified groups of 30 healthy young males aged 18 to 25 years: elite track and field athletes (n = 10), recreationally active individuals (n = 10), and sedentary controls (n = 10). Measurements included serum MOTS-c, SOD, post-exercise MDA, VO₂max, forced vital capacity, vertical jump height, handgrip strength, back muscle endurance, and post-fatigue back muscle force. Serum MOTS-c increased progressively across groups (athletes: 507.51 ± 67.42 pg/mL; active: 440.32 ± 32.83 pg/mL; sedentary: 319.31 ± 99.07 pg/mL; p < 0.001; Hedges’ g = 2.13 for athlete vs. sedentary comparison). Serum MOTS-c was strongly correlated with absolute VO₂max (r = 0.892), SOD (r = 0.847), post-exercise MDA (r = −0.910), back muscle endurance (r = 0.725), and post-fatigue back muscle force (r = 0.812) (all p < 0.001). In exploratory hierarchical regression, post-exercise MDA remained significantly associated with serum MOTS-c after adjustment for VO₂max, whereas SOD was not independently associated. Handgrip strength showed no significant correlation with MOTS-c (r = 0.315, p = 0.090). These findings suggest that serum MOTS-c is associated with exercise capacity and circulating antioxidant markers in young males, although the cross-sectional design precludes causal inference. Full article

Exercise is proposed to influence oxidative stress and mitochondrial-biogenesis pathways relevant to brain aging, but how exercise intensity relates to these markers alongside hippocampal structure remains unclear. This study examined treadmill exercise at three fixed speeds (15, 20, 30 m/min), corresponding to literature-derived, non-individually validated nominal intensity classifications (~40–50%, 55–65%, 70–75% VO₂max), on biochemical markers (PGC-1α, MDA, SIRT2, BDNF, irisin) and, as a secondary outcome, hippocampal histology, in young rats and in rats with D-galactose-induced accelerated aging. Sixty-four male Wistar Albino rats (3 months old, 220–350 g) were assigned to control and low-, moderate-, and high-intensity exercise groups within each model category (n = 8/group); after six weeks, serum was collected for biochemical analyses and brain tissue was collected for exploratory histological evaluation. In young rats, MDA and SIRT2 differed significantly among groups (p < 0.05); PGC-1α, BDNF, and irisin did not. In D-galactose-treated rats, none of the five markers differed significantly; MDA and SIRT2 showed large effect sizes (ε² = 0.207 and 0.199) despite non-significant p-values; given the small sample size, this should be read as an imprecise estimate consistent with a range of true effects, including no effect, rather than as evidence of a masked effect. Qualitative, single-rater H&E staining suggested greater dentate gyrus granule-cell density in exercised D-galactose-treated rats versus controls; without neuronal, neurogenesis, or glial markers, this remains a preliminary, hypothesis-generating impression rather than confirmed evidence of neurogenesis. Overall, treadmill exercise was associated with significant changes in oxidative-stress and sirtuin markers across nominal exercise intensities in young rats, the study’s primary contribution; the histological observation requires confirmation with quantitative stereology, specific immunomarkers, and behavioral testing before mechanistic claims can be made. Full article

Age-related declines in physical capacity may partly reflect impaired mitochondrial bioenergetics and oxidative stress. This systematic review and meta-analysis evaluated the effects of oral coenzyme Q10 (CoQ10) supplementation on muscle health and physical capacity in adult populations with a study-level mean or median age ≥ 40 years. MEDLINE, Embase, Web of Science, Scopus, and CENTRAL were searched through July 2026 for randomized controlled trials lasting ≥2 weeks. Directly usable evidence formed primary random-effects models, whereas assumption-dependent estimates were included only in sensitivity analyses. Effect measures were expressed as mean differences (MDs) or Hedges’ g, as appropriate. Thirty-three trials involving 3317 randomized participants were included, and 21 contributed to meta-analysis. The relative VO₂peak/VO₂max estimate was small and imprecise (5 studies, n = 172; MD 0.73 mL·kg⁻¹·min⁻¹, 95% CI −0.07 to 1.54; I² = 0%; low certainty) and remained compatible with no benefit. Primary estimates were also uncertain for 6-min walking distances, handgrip strength, lower-limb strength, chair-rise performance, exercise duration, and muscle/lean-tissue quantity. Sensitivity analyses did not materially alter the overall interpretation. Evidence certainty was low or very low for all key outcomes. Current evidence does not establish clinically meaningful benefits of CoQ10 supplementation for aerobic capacity, muscle health, or physical function. Full article

This study examined the effect of breathing rate (BR) on prefrontal cortical (PFC) activation during single-task and dual-task (e.g., Trail Walking Task (TWT)) conditions in a diverse aging population. We hypothesized that higher BR would be associated with increased PFC activation, particularly during dual-task walking. In this cross-sectional study, 45 adults (mean age 50.31 ± 20.19 years; 27 females) walked on an instrumented treadmill at a self-selected pace under single-task and TWT conditions. Resting BR was measured using a smart shirt, and functional near-infrared spectroscopy assessed PFC oxygenated hemoglobin (HbO₂) and deoxygenated hemoglobin (Hb) during TWTA (numbers only) and TWTB (numbers and letters). Linear mixed-effects models evaluated the effects of BR, task, and their interaction on PFC activation, controlling for age and cardiorespiratory fitness (VO₂ max). The results showed significant differences in Hb and HbO₂ between single- and dual-task conditions across BR levels. Individuals with higher BR exhibited greater PFC activation during TWT, whereas lower BR was associated with reduced activation and more efficient attentional resource allocation. BR was not associated with walking speed. These findings suggest that higher BR reflects increased neural effort during dual-task walking and highlight breathing as a potential modifiable factor influencing cognitive-motor performance and fall risk. Full article

Interval training is a popular method for enhancing athletic performance, adjustable through speed, distance, and rest. The acute physiological and subjective responses to isolated manipulation of these components remain unclear. This study examined acute physiological and perceptual responses to systematic manipulation of speed, distance, or rest during interval training. Twenty-two young male physical-education students (average age 25.2 ± 3.5) with high baseline physical activity but no prior structured interval-training experience completed three randomized interval protocols. In all protocols, the first interval was identical (92% vVO₂max, 250 m, 180 s rest). In the remaining five intervals, either speed, distance, or recovery duration was progressively changed in 8% steps (speed, distance, and rest protocols, respectively), while the other two components were kept constant. Blood lactate (La), oxygen consumption (VO₂), ventilation (VE), respiratory exchange ratio (RER), heart rate (HR), and rating of perceived exertion (RPE) were measured throughout. Overall, the speed protocol elicited the highest average peak values across all measured parameters (p < 0.001). However, the percentage change in VO₂ from Interval 1 to Interval 6 did not differ significantly between the speed and distance protocols. Between-protocol differences varied across outcomes: the speed protocol elicited greater changes in Lactate from Interval 2 onward and in VE and HR from Interval 3 onward (p < 0.05). Rate of perceived exertion was highest during the speed protocol (p < 0.001) but did not differ significantly between distance and recovery protocols. Applying the same relative 8% progression across interval components elicited distinct physiological responses. Progressive increases in running speed produced greater acute peak cardiorespiratory and metabolic responses than progressions in distance or reductions in recovery duration. Full article

Background/Objective: Insufficient research has examined the muscle damage and inflammatory effects of training performed in a fasted state with reduced (low) glycogen reserves. Methods: This study aimed to investigate the acute effects of exercise sessions performed under fasting (FST) and liquid nutrient-supplemented postprandial (PPD) conditions, as well as with full and reduced body glycogen stores, on muscle damage markers creatine kinase (CK) and lactate dehydrogenase (LDH), and the inflammatory marker interleukin-6 (IL-6). Eleven male amateur football players (mean age 19.91 ± 1.64 years) were included in the study. Participants performed a single 60 min aerobic endurance exercise session at 70% VO₂max under the liquid nutrient-supplemented PPD condition, and two 60 min sessions with a 60 min recovery interval under 10–12 h FST conditions. Data were analyzed using paired samples t-test, ANOVA, Wilcoxon, and Friedman tests, depending on parametric and nonparametric assumptions. Results: In pre-exercise (PRE-FE) measurements, no significant differences were observed between the FST and PPD conditions for GLU, CK, LDH, and IL-6 levels. In postexercise (POST-FE) measurements, GLU levels were significantly higher in the PPD condition than in the FST condition (p < 0.05), whereas LA, CK, LDH, and IL-6 levels did not differ significantly between the two conditions. In the FST condition, following the second exercise session performed with default reduced glycogen availability (POST-SE), CK levels significantly increased from 279.36 ± 16.7 U/L to 335.63 ± 20.3 U/L, LDH levels from 178.72 ± 38.1 U/L to 208.09 ± 50.7 U/L, and IL-6 levels from 2.60 ± 2.4 pg/mL to 8.69 ± 5.8 pg/mL (p < 0.05). In the PPD condition, no significant changes were observed in any of the parameters following a single exercise session (p > 0.05). Conclusions: The two-a-day training approach performed with default reduced glycogen availability may increase muscle damage and inflammatory responses. These findings are considered as an inference that low-glycogen training should not be implemented during the pre-competition period because of the risk of inducing muscle damage. Full article

Background and Objectives: Comprehensive physical profiling is important for monitoring athletic development in youth soccer players (YSP), yet integrated data from competitive South American players remain limited. This study aimed to characterize the anthropometric profile, neuromuscular performance, and cardiorespiratory fitness of competitive Chilean YSP and explore associations among these components. Methods: This cross-sectional study included 24 male YSP from a Chilean professional club academy. Participants underwent anthropometric assessment, bilateral quadriceps isometric strength testing, vertical jump testing (Squat Jump [SJ], Countermovement Jump [CMJ], and Abalakov Jump [ABK]), and maximal cardiopulmonary exercise testing. The primary analysis was an integrated characterization of anthropometric, neuromuscular performance, and cardiorespiratory fitness. Secondary exploratory analyses included correlations with false discovery rate adjustment and multiple linear regression. Results: Participants had a median age of 13.5 years (IQR: 13.0–14.0) and a BMI of 21.1 ± 1.6 kg·m⁻². Mean bilateral quadriceps strength was 406.1 ± 70.0 N, while mean jump heights were 24.6 ± 4.2 cm for SJ, 28.4 ± 3.7 cm for CMJ, and 33.4 ± 5.3 cm for ABK. The average relative VO₂peak was 55.0 ± 4.7 mL·kg⁻¹·min⁻¹, while absolute VO₂peak was slightly higher than predicted. Bilateral quadriceps strength was positively associated with all three jumps before FDR adjustment; after FDR correction, the associations with CMJ and ABK remained statistically significant, whereas the association with SJ did not. Relative VO₂peak was not associated with CMJ performance. Conclusions: This study provides an integrated characterization of physical performance within this cohort of youth soccer players. Quadriceps strength was associated with vertical jump performance, whereas relative VO₂peak was not associated with CMJ, supporting assessment of neuromuscular and cardiorespiratory capacities. Full article

Background/Objectives: Cardiorespiratory fitness (CRF), measured as VO₂peak during cardiopulmonary exercise testing (CPX), represents a fundamental marker of cardiovascular health. Heart Rate Variability (HRV) assesses cardiac autonomic regulation (CAR) non-invasively, though technical issues limit clinical use. Combining CRF and CAR may provide complementary information on cardiovascular and autonomic function. We examined the relationship between CRF and HRV using a composite autonomic index, the Autonomic Nervous System Index (ANSI), which incorporates multiple HRV variables accounting for age/sex-related influences. Methods: This cross-sectional study involved 200 adults undergoing preventive health evaluation without overt cardiometabolic disease. CRF was expressed as VO₂peak and as VO₂peak percentile from the FRIEND registry. CAR was assessed at rest using HRV. Results: We observed significant correlations between VO₂peak and several HRV variables, with ANSI showing the strongest association (r = 0.457, p < 0.001). In simple regressions, ANSI was linked to VO₂peak (R² = 0.175, p < 0.001) and VO₂peak percentile (R² = 0.209, p < 0.001). In multiple regression, several autonomic variables were retained for VO₂peak, whereas ANSI was the only autonomic variable retained for VO₂peak percentile. This association remained significant after adjustment for age, sex, smoking, and anthropometric measures. Trend analyses (p < 0.001) and ordinal regression analyses (p < 0.001) further substantiated these findings. A 10-point increase in ANSI corresponded to an OR of 1.39 for belonging to a higher CRF percentile category. Conclusions: Multiple HRV indices were associated with CRF, with ANSI showing the strongest association. These findings highlight the potential of ANSI as a simple, integrated measure of CAR in individuals with different levels of CRF. Full article

Accessible assessment of aerobic fitness is important for adults with metabolic syndrome when cardiopulmonary exercise testing is unavailable. This study aimed to evaluate participant-level agreement between Six-Minute Walk Test (6MWT)-based equations and estimates derived from total Bruce treadmill duration. Using a single-city cross-sectional method-comparison design, 105 newly recruited adults, comprising 67 women and 38 men, completed standardized 6MWT and graded treadmill assessments. Agreement was evaluated using mean bias, mean absolute error (MAE), root mean square error (RMSE), Pearson correlation, calibration, proportional-bias regression, and Bland–Altman limits of agreement. Mean Bruce-derived estimated peak oxygen uptake (${\mathrm{VO}}_{2peak}$) was $23.42\pm 1.87$ mL·kg⁻¹$·$min⁻¹. Model 1 produced $15.90\pm 1.72$, with a mean bias of $-7.53$, an RMSE of 7.77, and limits of agreement from $-11.29$ to $-3.76$. Model 3 produced $16.78\pm 3.28$, with a mean bias of $-6.65$, an RMSE of 7.11, and limits from $-11.60$ to $-1.70$. Both models systematically underestimated Bruce-derived values, and Model 3 showed proportional bias. Model 2 produced $99.31\pm 4.82\%$ on its original age- and sex-adjusted percentage-predicted scale. It was not converted to mass-specific units because the participant-specific reference values required for a valid back-conversion were unavailable. The observed bias and limits of agreement indicated that Models 1 and 3 did not achieve close participant-level agreement with the Bruce-derived approach. Validation against directly measured oxygen uptake remains necessary before clinical or public-health use. Full article

This study aimed to analyze the placebo effect associated with caffeine ingestion on cycling performance at the respiratory compensation point (RCP). Nineteen trained male cyclists (age: 28.1 ± 9.4 years; body mass: 71.0 ± 8.4 kg; VO₂max: 67.1 ± 6.7 mL·kg⁻¹·min⁻¹) completed two time-to-exhaustion (TTE) tests at the power output associated with RCP under two conditions: caffeine informed/placebo ingested (Expectancy) and non-ingested (Control), separated by 4–7 days. Total work (kJ) was recorded as the main performance variable and heart rate and rating of perceived exertion were measured. The side effects were evaluated through a questionnaire administered the day after the expectancy condition. TTE performance was similar (157.31 ± 63.45 kJ Expectancy vs. 154.83 ± 56.19 kJ Control, p = 0.68, trivial d = 0.09). Heart rate did not differ between trials (173.05 ± 9.65 bpm vs. 173.32 ± 9.74 bpm, p = 0.71 trivial d = −0.07), and RPE reached maximal values. Mild side effects—mainly increased activeness and muscular pain (31.3%)—were reported following placebo ingestion. In conclusion, this study did not detect an effect of a caffeine expectancy manipulation on time to exhaustion at the RCP in trained male cyclists. Heart rate was similar between conditions, and mild subjective symptoms were reported following the expectancy condition, although these cannot be causally attributed to expectancy. Full article

Background: High-intensity interval training (HIIT) is a time-efficient exercise strategy, but its effects in older adults remain incompletely established. Objective: Our objective is to synthesize evidence on the effects of HIIT and aerobic interval training (AIT) on cardiorespiratory, metabolic, functional, cognitive, psychological, and quality-of-life outcomes in older adults. Methods: This systematic review was reported in accordance with PRISMA 2020. PubMed, Scopus, and Web of Science were searched through 13 May 2026 for randomized and non-randomized longitudinal intervention studies involving participants with a mean or median age ≥ 60 years. Titles/abstracts and full texts were screened by one reviewer, with uncertain eligibility resolved through discussion with the supervisory team. Data were extracted by one reviewer and independently verified by a second reviewer. The review was retrospectively registered in INPLASY (INPLASY202660027). Results: Twenty-five eligible reports were included, representing approximately 2818 unique participants. The most consistent findings concerned cardiorespiratory fitness, with improvements in VO₂peak and exercise tolerance reported across several populations. Selected functional and metabolic benefits were also observed, whereas cognitive, psychological, and quality-of-life findings were more limited and heterogeneous. HIIT produced comparable or greater improvements than moderate-intensity continuous training in some studies, but overall superiority was not established. Feasibility and adherence were generally favourable, although adverse-event reporting was inconsistent. Conclusions: HIIT/AIT may improve cardiorespiratory fitness and selected functional outcomes in older adults. However, confidence in these findings is limited by heterogeneity in populations, protocols, and outcomes, together with the predominance of risk-of-bias concerns across the included evidence. The available findings do not establish overall superiority, comparative safety, or an optimal HIIT/AIT prescription. Full article

This study fabricated a silver-based composite photocatalytic material (Ag/AgVO₃/g-C₃N₄) for antibiotic degradation driven by visible light. The composite was prepared using the water bath method, and its morphology, structure and optical properties were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Ultraviolet-Visible (UV-vis) diffuse reflection spectroscopy. The photocatalytic activity of the composite was evaluated within 240 min under visible-light irradiation, and its degradation effect was quantified using tetracycline hydrochloride as the target pollutant, applying different conditions of composite proportions and dosage, initial concentration of the contaminant, and pH. The experimental results demonstrated that the composite doped with Ag⁺ had a higher degradation effect on tetracycline hydrochloride. The highest degradation rate of tetracycline hydrochloride (reaching 86.64%) was achieved at a composite ratio of Ag/AgVO₃/5g-C₃N₄, dosage of 0.8 g·L⁻¹, and initial concentration of tetracycline hydrochloride of 10mg·L⁻¹. This rate is approximately 1.4 times and 1.7 times those of the pure-phase g-C₃N₄ and AgVO₃, and the degradation rate remains stable at 81.52% after 4 cycles of experiments. The favorable stability of the photocatalyst was also verified through a stability test. Full article

Physical exercise is a major determinant of health and functional capacity, yet direct comparisons among contemporary gym-based exercise modalities remain limited. This cross-sectional study compared the fitness, dietary, and supplement-use profile of 148 healthy recreational adults (72 men and 76 women; aged 18–45 years) engaged in mixed aerobic-resistance training (n = 52), Pilates (n = 46), or CrossFit (n = 50). Participants underwent cardiopulmonary exercise testing to determine the maximal oxygen uptake (VO₂max) and ventilatory anaerobic threshold (VAT). Body composition, handgrip strength, flexibility, Mediterranean diet adherence, and supplement use were also assessed. Participants in CrossFit and mixed training showed higher VO₂max and lower fat mass than the Pilates participants. Pilates showed higher VAT expressed as a percentage of VO₂max; however, this finding should be interpreted as a relative submaximal profile rather than evidence of superior overall aerobic fitness. Mixed training and CrossFit also showed more favorable body composition profiles, while mixed training demonstrated superior handgrip strength. Flexibility did not differ significantly among exercise modalities. Mediterranean diet adherence showed limited and sex-specific differences, which were attenuated after adjustment for age and training age. Overall, exercise modality was associated with distinct physiological and nutritional characteristics, with CrossFit and mixed training showing greater cardiorespiratory fitness and more favorable body composition characteristics, whereas Pilates was linked to a different submaximal exercise profile and specific lifestyle-related patterns. These findings should be interpreted with caution given the cross-sectional design and the possibility of self-selection bias. Full article