مرکز منطقه ای اطلاع رسانی علوم و فناوریJournal of Sports Physiology and Athletic Conditioning2783-30386202026914Rethinking the Biology of Skeletal Muscle Hypertrophy: Beyond mTOR and Acute Muscle Protein SynthesisRethinking the Biology of Skeletal Muscle Hypertrophy: Beyond mTOR and Acute Muscle Protein SynthesisenShahinRiyahi MalayeriDepartment of Physical Education and Sport Sciences, ET.C., Islamic Azad University, Tehran, Iran.0000000169894821Reza RostamiDepartment of Physical Education and Sport Sciences, ET.C., Islamic Azad University, Tehran, Iran.Mahmoud ZohrabZadehDepartment of Exercise Physiology, CT.C., Islamic Azad University, Tehran, Iran.2026428Dear Editor, Skeletal muscle hypertrophy remains one of the most extensively investigated adaptations to resistance training (RT), yet its underlying biology is considerably more complex than the conventional model of “mechanical loading - mTOR activation - muscle protein synthesis (MPS) - muscle growth” (1,2). Although this framework has been fundamental to the development of contemporary exercise physiology, recent evidence indicates that hypertrophy is better understood as an emergent phenotype arising from the interaction of mechanical, molecular, cellular, nutritional, and individual factors (2,13,15). We suggest that the current discussion should move beyond the isolated interpretation of acute anabolic signaling and instead consider the integration of mechanotransduction, translational capacity, protein turnover, satellite-cell activity, and individual responsiveness (2,13,15). Mechanical tension remains the most defensible proximal stimulus for resistance-training-induced hypertrophy (1,2,10). However, the biological interpretation of mechanical tension has evolved. Mechanical loading is detected through multiple structures within the muscle fiber and its extracellular environment, including the sarcolemma, cytoskeleton, costameric complexes, integrin-associated structures, and the extracellular matrix. These systems convert mechanical deformation into intracellular signals that regulate transcription, translation, cytoskeletal remodeling, and cellular growth (2,10,15). Accordingly, the external characteristics of a resistance exercise—load, repetitions, range of motion, contraction type, and proximity to failure—should not be regarded as direct determinants of hypertrophy. Rather, they modify the internal mechanical and metabolic environment that ultimately governs adaptation (1,6,10,18). This distinction has important implications for the interpretation of mTORC1 signaling. Activation of mTORC1 and its downstream effectors, including p70S6 kinase and 4E-BP1, is clearly involved in the regulation of translational activity following resistance exercise (2,13). Nevertheless, transient increases in phosphorylation of anabolic signaling proteins should not be equated with long-term muscle growth (2,13,15). The hypertrophic phenotype develops through repeated exposure to mechanical stimuli and the cumulative remodeling of muscle tissue. Consequently, molecular signaling should be interpreted as part of a network rather than as a single molecular switch responsible for hypertrophy (2,13,15). A similar caution is warranted regarding MPS. Resistance exercise increases MPS during recovery, and amino acid availability can further augment this response (4,11,13). However, the relationship between an acute post-exercise increase in MPS and subsequent hypertrophy is not necessarily linear. The timing, magnitude, duration, and protein fraction measured are critical (2,13). Myofibrillar protein synthesis is more directly related to contractile tissue remodeling than total MPS, while mitochondrial, sarcoplasmic, and extracellular matrix proteins may exhibit distinct temporal responses (13,17). Furthermore, the acute MPS response can be influenced by training status and does not necessarily predict the magnitude of hypertrophy over subsequent weeks or months (2,13). This issue suggests that the field should increasingly distinguish between anabolic signaling, acute protein synthesis, and net protein accretion. Muscle hypertrophy ultimately reflects the cumulative balance between protein synthesis and protein degradation, integrated across repeated training and recovery cycles (13,17). A transient increase in MPS is therefore necessary in many circumstances but is not, by itself, sufficient evidence that a specific intervention will produce superior hypertrophy. Recent conceptual and experimental work has emphasized that resistance exercise affects both synthetic and degradative processes and that their temporal coordination may be more informative than isolated measurements of MPS (13,17). Another relatively underappreciated determinant is ribosomal biogenesis. Muscle growth requires not only activation of existing translational machinery but also sufficient translational capacity to sustain increased protein production over time. Repeated resistance exercise can increase ribosomal content and alter the molecular systems controlling ribosomal RNA synthesis. This provides a plausible mechanistic bridge between repeated acute anabolic responses and chronic hypertrophy (2,13,17). In this context, training volume may influence hypertrophy partly by modifying the translational capacity of skeletal muscle rather than merely by increasing the number of mechanical stimuli (17,19). Satellite cells provide a further layer of biological regulation. These muscle-resident progenitor cells respond to mechanical loading and participate in muscle remodeling, regeneration, and, under some circumstances, myonuclear accretion. Importantly, the contemporary literature does not support a simplistic interpretation in which satellite cells are either universally essential or completely irrelevant to hypertrophy (2,15). Their contribution appears to depend on training history, exercise characteristics, muscle group, magnitude of the hypertrophic stimulus, and the physiological context. Recent evidence showing differences in satellite-cell responses among individuals with different hypertrophic trajectories reinforces the concept that cellular remodeling may contribute to interindividual variability (2,15). The concept of individual responsiveness may therefore deserve greater prominence in hypertrophy research. Identical resistance-training programs do not produce identical morphological adaptations (1,18). Recent investigations have demonstrated that individuals can respond differently to alternative overload progression strategies, with some participants exhibiting substantially greater hypertrophy under one progression model than another. Such findings challenge the assumption that a universal resistance-training prescription can optimize hypertrophy across all individuals (18,19). Instead, the field may need to move toward adaptive training models in which training volume, loading strategy, proximity to failure, exercise selection, and progression are adjusted according to measurable responses. The debate surrounding proximity to failure illustrates this principle. Contemporary evidence suggests that training closer to momentary muscular failure may enhance hypertrophic responses under some conditions, but failure itself is not consistently required (3,6,7). Indeed, recent controlled work has reported similar hypertrophy when resistance-trained individuals performed sets to momentary failure or terminated sets with repetitions in reserve (8). The physiological consequence of failure may therefore depend on the interaction between load, volume, exercise selection, fatigue, and the muscle's capacity to maintain high mechanical tension (3,6,8). Training volume presents a similar complexity. Higher weekly volumes are generally associated with greater hypertrophy, but the relationship is not necessarily unlimited or linear (1,19). The traditional interpretation that “more sets always produce more growth” is increasingly difficult to defend without considering training status, recovery capacity, exercise selection, and the distribution of volume across the week (1,19). Interestingly, recent experimental evidence indicates that even a large increase in training volume does not necessarily impair hypertrophy or anabolic-catabolic molecular signaling in trained individuals (20). This suggests that the biological response to training volume is highly context-dependent. Nutritional regulation should also be integrated into this model. Dietary protein supplies the amino acids required for tissue remodeling, while essential amino acids—particularly leucine—can influence nutrient-sensing pathways involved in translational regulation (4,11). However, protein intake does not operate independently of mechanical loading. The interaction between resistance exercise and nutrition is more appropriately understood as a coordinated system in which mechanical stimuli establish the requirement for remodeling while amino acid availability supports the substrate and signaling environment necessary for protein accretion (4,11,13). Recent work also indicates that the timing of protein ingestion may be less important than achieving an adequate total daily protein intake in resistance-trained individuals (4,11). Another emerging issue is the distinction between muscle size and muscle quality. Hypertrophy assessed through a single anthropometric measurement or whole-body lean mass may obscure regional and architectural adaptations. Muscle thickness, anatomical cross-sectional area, muscle volume, fascicle length, pennation angle, and tissue composition can change heterogeneously within the same muscle (9,10). Therefore, future hypertrophy studies should increasingly combine morphological, architectural, molecular, and functional outcomes. This multidimensional approach would reduce the risk of interpreting small changes in body composition as direct evidence of contractile tissue hypertrophy (9). The 2026 American College of Sports Medicine overview of reviews further supports a more nuanced interpretation of resistance-training prescription. Across more than 30,000 participants and 137 systematic reviews, resistance training consistently improved muscle size and function, whereas relatively few individual prescription variables demonstrated uniform effects across outcomes (18). Higher weekly volume was associated with greater hypertrophy, but several commonly emphasized variables—including training to momentary fatigue, equipment type, exercise complexity, time under tension, blood-flow restriction, and periodization—did not consistently influence all outcomes (18). These findings emphasize that hypertrophy should be viewed as a biological adaptation emerging from an integrated training stimulus rather than from a single optimal training variable. Collectively, the evidence supports a revised conceptual framework in which mechanical loading initiates mechanotransduction; intracellular signaling involving mTORC1 and related pathways regulates translational activity; repeated stimulation modifies ribosomal capacity; MPS and protein degradation determine the net remodeling environment; satellite cells and myonuclear adaptations contribute to tissue plasticity; and nutritional availability modulates the capacity to sustain these processes (2,13,15,17). The magnitude of the final hypertrophic phenotype is subsequently shaped by training history, recovery, age, sex, nutritional status, and individual responsiveness (1,18,19). We therefore propose that future research should move from the question “Which training variable maximizes MPS?” toward the more physiologically meaningful question “Which combination of mechanical, molecular, cellular, and nutritional signals maximizes sustained contractile protein accretion in a given individual?” Addressing this question will require longitudinal studies integrating repeated measures of MPS, proteolysis, ribosomal biogenesis, satellite-cell behavior, muscle architecture, and functional performance (2,13,17). Such an approach may help explain why apparently similar training programs produce markedly different hypertrophic outcomes. In conclusion, mTORC1 and MPS remain central components of skeletal muscle hypertrophy, but neither should be regarded as a sufficient explanation of the hypertrophic phenotype (2,13,15). The emerging evidence favors an integrated model in which mechanical tension is translated through multiple intracellular systems and ultimately interacts with translational capacity, protein turnover, cellular remodeling, nutrition, and individual biology (2,13,15,17). Reframing hypertrophy in this manner may improve mechanistic understanding while also providing a stronger scientific foundation for individualized resistance-training prescription (18,19).

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مرکز منطقه ای اطلاع رسانی علوم و فناوریJournal of Sports Physiology and Athletic Conditioning2783-30386202026914The effect of a selected wrestling training period and citrulline malate consumption on troponin t and i levels in amateur wrestlersThe effect of a selected wrestling training period and citrulline malate consumption on troponin t and i levels in amateur wrestlersenMasoumehHosseiniDepartment of Physical Education and Sport Sciences, East Tehran Branch, Islamic Azad University, Tehran, Iran.0000000184571924Erfan HosseinyazdiMSc of Exercise Physiology, Department of Physical Education and Sport Sciences, ET.C. , Islamic Azad University, Tehran, Iran.2026122  Abstract Background and Objective: Stresses resulting from heavy and relatively intense training may cause inflammatory responses and increase muscle damage indices. The purpose of the present study was the effect of a selected wrestling training period and citrulline malate consumption on troponin t and i levels in amateur wrestlers.   Methods: In this semi-experimental study with a pre-test-post-test design, 20 male wrestlers aged 18 to 24 years with 2-3 years of wrestling experience in the city of Qiamdasht were voluntarily selected as a purposive and accessible sample and randomly divided into two groups of 10: selected exercise and selected exercise + citrulline malate. The training protocol included a wrestling routine for 4 weeks, three sessions per week. The supplement groups took 6 grams of citrulline malate powder dissolved in 500 ml of water and consumed it with meals daily for 4 weeks. Data were evaluated using analysis of covariance (P ≤0.05).   Results: The results showed that a selected period of wrestling training and the consumption of citrulline malate had a significant effect on the levels of troponin t and i in amateur wrestlers and caused a decrease (p=.000) Conclusion: It seems that wrestling training combined with the consumption of citrulline malate caused a decrease Levels of cardiac risk markers...

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مرکز منطقه ای اطلاع رسانی علوم و فناوریJournal of Sports Physiology and Athletic Conditioning2783-30386202026914Comparative Effects of Eight Weeks of High-Intensity Functional Training in Fasted versus Fed States on the Lipid Profile of Overweight Adolescent BoysComparative Effects of Eight Weeks of High-Intensity Functional Training in Fasted versus Fed States on the Lipid Profile of Overweight Adolescent Boysen Sadegh AbdollahiDepartment of Physical Education and Sport Sciences, Bushehr Branch, Islamic Azad University, Bushehr, Iran. Mohadeseh BandarRigi Department of Physical Education and Sports Sciences, Shiraz University, Shiraz, IranMohammad AliAzarbayjani Department of Sports Physiology, Central Tehran Branch, Islamic Azad University, Tehran, Iran0000-0002-3502-74872026613Background: Overweight is commonly associated with lipid abnormalities and an increased risk of metabolic disorders. Considering the beneficial role of exercise in improving blood lipid levels, the present study aimed to compare the effects of eight weeks of high intensity functional training (HIFT) performed in the fasted state versus the fed state on the lipid profile of overweight adolescent boys. Materials and Methods: In this quasi-experimental study, 36 overweight adolescent boys were selected and randomly assigned to three equal groups (n = 12 each): fasted training, fed training, and control. Participants in the training groups performed an eight-week HIFT program, three sessions per week, consisting of eight exercises targeting the upper body, core, and lower body. Blood samples were collected 48 hours before the first training session and 48 hours after the final session to assess lipid profile indices. Statistical analysis included analysis of covariance (ANCOVA), the Kolmogorov–Smirnov test for normality, and paired t tests to compare within group mean differences. Results: The results showed that after eight weeks of training, both exercise groups demonstrated significant reductions in triglycerides (TG), total cholesterol (TC), and low-density lipoprotein (LDL), along with a significant increase in high-density lipoprotein (HDL) (p < 0.05). Furthermore, ANCOVA results indicated significant differences between the fasted and fed training groups in the changes observed in TG, TC, LDL, and HDL (p < 0.05), with the fasted training group showing greater improvements in lipid profile indices. Conclusion: High-intensity functional training improves the lipid profile in overweight adolescents, and performing this training in a fasted state may produce more favorable effects on lipid indices compared with training in a fed state. Therefore, fasted HIFT may be considered an effective strategy for improving metabolic health in overweight adolescents.

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مرکز منطقه ای اطلاع رسانی علوم و فناوریJournal of Sports Physiology and Athletic Conditioning2783-30386202026914Thermogenesis of brown fat adipose tissue in response to aerobic exerciseThermogenesis of brown fat adipose tissue in response to aerobic exerciseenSarvenaz AliasgariDepartment of Physical Education and Sport Sciences, CT.C., Islamic Azad University, Tehran, Iran.Mohammad AliAzarbayjaniDepartment of Physical Education and Sport Sciences, CT.C., Islamic Azad University, Tehran, Iran 0000000235027487sirvan AtashakDepartment of physcical education and sport since, mah.c., Islamic Azad iniversity, Mahabad, Iranmaghsoudpeeri1. Department of Sports Physiology, Central Tehran Branch, Islamic Azad University, Tehran, Iran0000-0003-1415-7319Saleh RahmatiDepartment of Physical Education, Pardis Branch, Islamic Azad University, Pardis, Iran.00000001875117592026619Due to decreased physical activity and excessive energy intake, obesity and its related metabolic diseases have become increasingly prevalent worldwide. Aerobic exercise is recognized as an effective non-pharmacological strategy for obesity management, acting through multiple mechanisms, including increased energy expenditure, improved substrate utilization, and regulation of body composition. One proposed mechanism is the activation of brown adipose tissue thermogenesis. Brown adipose tissue is rich in mitochondria and expresses uncoupling protein 1 (UCP1), which enables the oxidation of glucose and fatty acids to generate heat rather than adenosine triphosphate. Through this process, BAT can contribute to daily energy expenditure and may help prevent excessive fat accumulation. Cold exposure, regular physical activity, and certain phytochemical compounds have been reported to activate thermogenic signaling pathways and enhance energy metabolism, partly through sympathetic stimulation and beta-3 adrenergic receptor activation in BAT. Although animal studies, particularly in rodent models, have suggested that aerobic exercise may stimulate brown fat thermogenesis and browning of white adipose tissue, evidence in humans remains limited and inconsistent. Some studies have reported beneficial effects, whereas others have failed to confirm a significant change in BAT activity after exercise training. Therefore, the thermogenic role of aerobic exercise in humans remains uncertain. Further well-designed clinical studies are needed to clarify whether exercise-induced activation of brown adipose tissue contributes meaningfully to obesity prevention and metabolic health.

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مرکز منطقه ای اطلاع رسانی علوم و فناوریJournal of Sports Physiology and Athletic Conditioning2783-30386202026914Effects of Aerobic Exercise and Tribulus terrestris Supplementation on Selected Physical Fitness Components and Body Composition in Physically Active WomenEffects of Aerobic Exercise and Tribulus terrestris Supplementation on Selected Physical Fitness Components and Body Composition in Physically Active WomenenZahraRasouliDepartment of Exercise Physiology, CT.C., Islamic Azad University, Tehran, Iran.Naser AmiriDepartment of Exercise Physiology, CT.C., Islamic Azad University, Tehran, Iran.Mania RouzbayaniDepartment of Exercise Physiology, CT.C., Islamic Azad University, Tehran, Iran.2026528Background: The present study aimed to investigate the effects of eight weeks of aerobic training and Tribulus terrestris supplementation on selected components of physical fitness and body composition in physically active women. Methods: This semi-experimental study employed a pretest–posttest design with a control group. Forty physically active women were randomly assigned to one of four groups (n = 10 each): control, Tribulus terrestris supplementation, aerobic training, and aerobic training combined with Tribulus terrestris supplementation. Body height, body weight, and body mass index (BMI) were assessed using a stadiometer and medical scale. Physical fitness variables included isometric strength (handgrip dynamometer), lower-body explosive power (Sargent vertical jump test), agility (4 × 9 m shuttle run), reaction time (reaction time apparatus), and dynamic muscular endurance (pull-up test). Measurements were obtained before and after the 8-week intervention. The aerobic training groups completed three exercise sessions per week for eight weeks. Participants in the supplementation groups consumed 1,250 mg/day of Tribulus terrestris (625 mg twice daily), while the placebo group received visually identical capsules containing starch. Data were analyzed using two-way analysis of covariance (ANCOVA), with statistical significance set at P < 0.05. Results: Aerobic training produced significant main effects on isometric strength, dynamic muscular endurance, and body composition (P < 0.05). Significant interaction effects between aerobic training and Tribulus terrestris supplementation were also observed for these variables. However, no significant effects were found for lower-body explosive power, agility, or reaction time (P > 0.05). In addition, Tribulus terrestris supplementation alone did not produce significant improvements in any of the measured physical fitness or body composition variables. Conclusion: Eight weeks of aerobic training combined with Tribulus terrestris supplementation improved isometric strength, dynamic muscular endurance, and body composition in physically active women, whereas supplementation alone was ineffective. These findings suggest that combining aerobic exercise with Tribulus terrestris supplementation may provide greater benefits for selected physical fitness components and body composition than supplementation alone.

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مرکز منطقه ای اطلاع رسانی علوم و فناوریJournal of Sports Physiology and Athletic Conditioning2783-30386202026914The effect of aerobic exercise combined with gallic acid on SOD and GPx in kidney tissue of rats exposed to cadmium.The effect of aerobic exercise combined with gallic acid on SOD and GPx in kidney tissue of rats exposed to cadmium.en Meysam ZayerchiDepartment of Physical Education and Sport Science, Ki.C., Islamic Azad University, Kish, IranSeyed AliHosseini Department of Sport Physiology, Marv.C, Islamic Azad University, Marvdasht, IranMohammad Ali AzarbayjaniDepartment of Physical Education and Sport Sciences, CT.C., Islamic Azad University, Tehran, Iran0000-0002-3502-7487Heshmatollah ParsianDepartment of Physical Education and Sport Science, ShQ.C., Islamic Azad University, Shahr-e Qods, IranRouhallah ErshadiDepartment of Physical Education and sport science, Bu.C., Islamic Azad University, Bushehr, Iran20251215Introduction: Environmental pollution, including cadmium, is associated with impaired organ function, including the kidneys. On the other hand, although the effect of exercise and some natural antioxidants on improving kidney function has been shown, the present study aimed to investigate the effect of aerobic exercise combined with gallic acid on SOD and GPx in kidney tissue of rats exposed to cadmium. Methods: In this experimental study, 42 male Sprague-Dawley rats, 8- 10 weeks old and weighing 200- 250 g, were randomly divided into 6 groups including 1) healthy control, 2) sham (only receiving gallic acid solution), 3) cadmium, 4) cadmium + gallic acid, 5) cadmium + exercise, and 6) cadmium + gallic acid + exercise. Rats in the cadmium groups consumed 5 mg/kg of cadmium dissolved in drinking water daily. The exercise groups ran for 30-60 minutes at a speed of 15 m/min and a 15-degree incline for eight weeks and five sessions per week. Also, 20 mg/kg of gallic acid was orally administered daily in food flavoring to rats. For data analysis, one-way ANOVA with Tukey post- hoc test and two-way ANOVA tests were used. The findings of the present study were analyzed in SPSS version 22 software with a significance level of 0.05. Results: The results showed that in the cadmium group, the levels of SOD and GPx were significantly lower than healthy control group (P=0.001). In the exercise and gallic acid groups, the levels of SOD and GPx were significantly higher than control group (P≤0.05). Also, exercise and gallic acid have an interactive effect on increasing SOD in the kidney tissue of rats exposed to cadmium (P≤0.05). Conclusion: It seems that aerobic exercise and gallic acid can probably enhance each other's effect in improving some antioxidant markers through common pathways.

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