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PubMed2026

Comprehensive multi-post-translational modifications profiling reveals age-associated remodeling in skeletal muscle.

Sarcopenia, characterized by the progressive loss of skeletal muscle mass and function, is a major hallmark of aging. Post-translational modifications (PTMs) play essential roles in regulating protein activity and cellular homeostasis; however, how multiple PTMs are remodeled during skeletal muscle aging remains incompletely characterized. Here, we performed comprehensive multi-layered proteomic profiling of skeletal muscle from young (3-month-old) and aged (24-month-old) mice, systematically quantifying the global proteome together with five major PTMs: acetylation, phosphorylation, N-glycosylation, O-glycosylation, and ubiquitination. In total, we identified 5 337 proteins and mapped thousands of PTM sites, generating an integrated atlas of age-associated proteomic and PTM remodeling in skeletal muscle. Pathway enrichment analyses revealed distinct modification-specific patterns: acetylation and phosphorylation were predominantly associated with metabolic and mitochondrial-related pathways; N-glycosylation was enriched in immune- and secretory pathway-related processes; O-glycosylation was associated with muscle contraction-related pathways; and ubiquitination was preferentially linked to cytoskeletal organization in muscle cells. Correlation analyses further uncovered diverse association patterns among different PTMs across protein- and modification-level datasets. Phosphorylation and ubiquitination exhibited consistent positive associations, whereas acetylation and ubiquitination showed both inverse and concordant co-variation patterns across subsets of proteins. Phosphorylation and O-glycosylation displayed heterogeneous association patterns across different proteins, and acetylation and phosphorylation demonstrated positive correlations with distinct age-associated directional changes across protein subsets. Together, these results provide a comprehensive, multi-dimensional view of age-associated remodeling of the skeletal muscle proteome and multiple PTM layers, offering a valuable resource for understanding molecular alterations accompanying muscle aging and sarcopenia.

Animals↗

PubMed2026

Transcriptomic insights into temperature regulation of proliferation and differentiation in skeletal muscle cells of Nibea albiflora.

Myogenesis involves sequential stages of muscle satellite cell activation, myoblast proliferation, differentiation, and fusion into multinucleated myotubes. Teleost muscle exhibits indeterminate growth and is highly sensitive to environmental temperature, yet the underlying mechanisms by which temperature regulate proliferation and differentiation remain poorly understood. In this study, we established a primary skeletal muscle cell culture from the yellow drum (Nibea albiflora), an economically important marine fish, and integrated morphological observations with comparative transcriptomics analysis to characterize cellular and molecular responses at 28 °C and 20 °C during both proliferation and differentiation stages. Phenotypic analysis revealed that 28 °C significantly enhanced both myoblast proliferation and myogenic differentiation ability compared with 20 °C. Transcriptomic profiling revealed that at 28 °C, differentiation upregulated extracellular matrix(ECM) organization, calcium signaling, and sarcomere assembly, while proliferation enhanced focal adhesion, growth factor signaling, and lipid metabolism. At 20 °C, differentiation was characterized by glutathione metabolism, and ferroptosis, while proliferation involved cytokine-cytokine receptor interaction and negative regulation of signal transduction. Core myogenic regulatory factors (MRFs), particularly myogenin, were strongly upregulated at 28 °C during the differentiation stage, serving as an internal control. Based on these findings, we propose a testable model that elevated temperature coordinates Ca2+-dependent MRF activation with ECM-integrin signaling to drive sarcomere assembly and muscle growth. Key differentially expressed genes (DEGs) regulating myogenesis in N. albiflora were also identified. This study provides a mechanistic framework for temperature adaptation in teleost skeletal muscle and identifies candidate genes for functional validation and marker-assisted selection, as well as a rationale for temperature management strategies to improve aquaculture yield of N. albiflora.

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PubMed2026

Muscular fiber properties and multi-omics investigation of larval and adult locomotor muscle in Microhyla fissipes.

During metamorphosis, Microhyla fissipes undergoes a critical transition from an aquatic to a terrestrial lifestyle, accompanied by significant remodeling of skeletal muscle. Notably, larval tail muscle degenerates, while adult hindlimb muscle develops. However, the molecular mechanisms that orchestrate these muscle type-specific adaptations to the changing environment remain unclear. In this study, histological observation, transcriptomics, and metabolomics were integrated to compare locomotor muscles from two stages: larval muscle from tail versus adult muscle from hindlimb. Our results revealed that adult muscle fibers exhibited reduced diameter and shorter sarcomere length compared to those of tadpoles. Transcriptomic analysis identified 4103 differentially expressed genes (DEGs), including 2182 up-regulated and 1921 down-regulated genes. Up-regulated genes were mainly involved in energy metabolism and cellular homeostasis pathways, including PPAR signaling and oxidative phosphorylation, whereas down-regulated genes were associated with carbohydrate metabolism and cell proliferation pathways, such as glycolysis/gluconeogenesis and PI3K-Akt signaling. Metabolic profiling indicated a metabolic shift from anaerobic to aerobic energy production, with 57 differential metabolites identified, mainly involved in protein metabolism and insulin-related pathways. Integrated multi-omics analysis further highlighted the AMPK and FoxO signaling pathways play key roles in this process. In conclusion, our findings demonstrate that the metabolic and structural differences between larval and adult skeletal muscles are mediated by AMPK- and FoxO-dependent signaling pathways, providing novel insights into the molecular mechanisms underlying adaptive development and locomotor transition in anuran amphibians.

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PubMed2026

Risk factors for loss of skeletal muscle mass in patients with chronic kidney disease on a low-protein diet.

OBJECTIVES: A low-protein diet (LPD) is recommended for patients with chronic kidney disease (CKD) to prevent a further decline in renal function. However, its impact on muscle mass in these patients remains unclear. This study investigated the risk factors for loss of muscle mass in patients with CKD on an LPD. METHODS: Eighty-four patients with predialysis CKD (59 men, mean age 61.9 ± 11.5 y) who participated in a multicenter randomized controlled trial initiated in 2014 were retrospectively reviewed. We collected data on baseline blood and urine tests, body composition, and dietary records at the start and end of the observation period. We evaluated muscle mass using the skeletal muscle index (SMI) and analyzed risk factors for a decrease in SMI during the 24-wk observation period, using logistic regression analysis. Variables with an association (P < 0.1) in univariate analysis, as well as age, sex, use of low-protein rice, and changes in protein intake, were subjected to multivariate analysis. RESULTS: SMI decreased in 50 patients (59.5%) during the observation period. Multivariate analysis identified significant associations of the SMI with serum albumin at baseline (odds ratio 0.11, 95% confidence interval 0.02-0.52, P = 0.004) and changes in energy intake while on the LPD (odds ratio 3.39, 95% confidence interval 1.00-11.43, P = 0.049). CONCLUSIONS: Risk factors for reduced SMI in patients with CKD on an LPD were malnutrition when initiating the LPD and reduced energy intake during its implementation. Clinicians should optimize nutritional status before initiation of an LPD and ensure adequate energy intake throughout treatment.

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PubMed2026

Skeletal Muscles Do Not Compete for Growth: Activating Additional Muscle Mass Does Not Compromise Changes in Muscle Size.

Kataoka, R, Yamada, Y, Hammert, WB, Sallberg, RW, Kang, A, Song, JS, Kassiano, W, Metcalf, EE, and Loenneke, JP. Skeletal muscles do not compete for growth: Activating additional muscle mass does not compromise changes in muscle size. J Strength Cond Res 40(9): 1043-1049, 2026-This study investigated whether the magnitude of muscle size and strength differed based on the amount of muscle recruited during training sessions. One hundred five untrained individuals were randomly assigned to 1 of 3 groups: low-load unilateral elbow flexion exercise (a) to failure (LL-Failure, n = 36), (b) to failure and low-load knee extension exercise to failure (LL-Failure + Legs, n = 33), or (c) a time-matched nonexercise control (CON, n = 36). Training groups completed 18 supervised sessions over 6 weeks (2 sets at 30% 1 repetition maximum [1RM] to failure). LL-Failure + Legs group performed 4 additional sets of knee extension exercise in each leg (20-30 RM). Muscle thickness on the anterior upper arm (60 and 70% sites) and elbow flexor 1RM strength of the trained arm were measured at pretesting and posttesting. Changes were compared using the ANCOVA function of Bayes Factors for Informative Hypotheses (prevalues as the covariate). Specific hypotheses were evaluated by comparing Bayes factors and the posterior probabilities between models. Six weeks of training led to increases in muscle size and strength. However, performing additional leg exercise did not attenuate the muscle growth in the anterior upper arm (0.19 cm) compared with performing only arm exercise to failure (0.18 cm). Changes in 1RM strength also did not differ between training groups (0.32 and 0.25 kg for LL-Failure and LL-Failure + Legs, respectively). Overall, there was no evidence for competition of adaptations in muscle size and strength under uncontrolled nutritional conditions. Whether greater training volume or limited nutrient intake induces a competition for resources warrants further investigation.

Humans↗

PubMed2026

Genome-wide characterisation of the myosin light chain gene family in Chinese perch (Siniperca chuatsi) and its expression patterns in muscle fibre types and injury response.

The Class II myosin light chain (myl) genes in Chinese perch (Siniperca chuatsi) have not yet been systematically characterised, and relationships with muscle fibre specification, development, and injury-associated remodelling remain unclear. In this study, fast and slow muscle fibres were initially distinguished using myofibrillar ATPase histochemistry. Subsequently, genome-wide mining identified 16 Class II myl genes, comprising eight essential and eight regulatory light-chain subunits. Their conserved-domain features, chromosomal distribution, phylogenetic relationships and expression profiles were analysed. Transcriptomic profiling showed that summed myl transcript abundance was higher in fast muscle than in slow muscle, accounting for 67.2% of the pooled myl transcript pool across the two muscle types (paired t-test, raw P = 0.036). mylpfa, myl1 and mylz3 were the major fast-muscle-associated genes, whereas myl10, myl2b and myl13 were preferentially expressed in slow muscle at the transcript level. These patterns support these genes as candidate fibre-type-associated expression markers. Developmental profiling identified stage-associated myl expression patterns, including a possible expression shift between mylpfb and mylpfa. In the descriptive injury-repair time course (d0-d7), FPKM profiles indicated that fast-muscle-associated genes (mylpfa, mylz3 and myl1) were lower at d1 and recovered by d3, whereas several slow-muscle-associated genes showed biphasic transcript-level increases. The slow-muscle-associated RLC gene mylpfb showed a delayed expression peak at d7. Notably, the embryonic isoform myl6l showed a modest increase from approximately 2 FPKM at d0 to 4-5 FPKM after injury, suggesting a possible injury-associated expression pattern that requires further validation. Together, these findings provide a genome-wide description of the Chinese perch myl gene family and identify candidate fibre-type-associated genes and descriptive injury-associated isoform expression patterns.

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PubMed2026

Impact of creatine supplementation alone or combined with exercise on inflammatory and clinical outcomes in chronic musculoskeletal pain treated in the rheumatological field: a systematic review.

Creatine supplementation has demonstrated ergogenic and anabolic effects in healthy and clinical populations. However, its potential therapeutic role in individuals with chronic musculoskeletal pain treated in rheumatological contexts remains unclear. The aim was to evaluate the efficacy and safety of creatine supplementation on pain, physical function/disability, quality of life, muscle strength, skeletal muscle mass, and inflammatory markers in people with chronic musculoskeletal pain usually treated from the rheumatological field. A systematic review was conducted following PRISMA guidelines. Searches were performed in MEDLINE, Web of Science, CINAHL, Scopus, and EMBASE up to July 2026. Eligible studies were randomized or nonrandomized clinical trials that provided creatine supplementation alone or in combination with exercise as a treatment compared to a control or placebo group. Eight studies (n = 189) were included, encompassing fibromyalgia, osteoarthritis, rheumatoid arthritis, and juvenile idiopathic arthritis. Creatine dosages varied from chronic low-dose to loading protocols (20 g/d, 2-5 g/d). Combined creatine plus resistance training may improve strength, skeletal muscle mass, and quality of life beyond exercise alone in osteoarthritis. Trials on fibromyalgia suggest an increase in muscle strength, but inconsistent effects on pain. Rheumatoid arthritis studies suggest gains in skeletal muscle mass and, in pilot studies, reduced disease activity. No major adverse events were reported. In conclusion, creatine supplementation alone may be insufficient to obtain clinical benefits, while combined with resistance exercise it could offer potential benefits for muscle strength, skeletal muscle mass and certain aspects of quality of life in these clinical conditions. However, evidence on pain and inflammation remains limited; Furthermore, the response across different clinical conditions is heterogeneous, highlighting the need for larger, high-quality trials.

Humans↗

PubMed2026

Low Carbohydrate Availability in Energy Balance Alters Bone Turnover and Muscle Proteomic Response With Limited Endocrine Disruption.

Training with low carbohydrate availability (LCA) has been proposed as an independent determinant of physiological perturbations commonly attributed to low energy availability (LEA) and to increase skeletal muscle oxidative machinery, yet the effects of LCA in isolation from LEA remain unclear. We examined whether short-term carbohydrate restriction under energy balance alters endocrine and metabolic markers associated with LEA and skeletal muscle proteomic response. In a randomized crossover design, eight trained males completed 4 days of either a low-carbohydrate high-fat diet (LOW; 12% carbohydrate, 69% fat, 19% protein) or a normal-carbohydrate diet (NORM; 62% carbohydrate, 19% fat, 19% protein), while undertaking daily cycloergometer exercise (15 kcal kg FFM-1 day-1) and maintaining energy availability at 45 kcal kg FFM-1 day-1. LOW induced a clear metabolic shift consistent with LCA, evidenced by elevated circulating free fatty acids, glycerol and β-hydroxybutyrate, in fasting conditions and fat oxidation at rest and during exercise, alongside reduced exercise glucose concentrations. Despite these responses, LOW did not alter insulin, testosterone, triiodothyronine, leptin, hepcidin, or P1NP. In contrast, β-CTX increased and IGF-1 decreased relative to NORM. Muscle glycogen concentration decreased only in LOW (40% ± 14%). Proteomic analysis identified 671 proteins; 57 differentially expressed in LOW relative to NORM were limited to fatty acid metabolism pathways and suppression of ribosomal, sarcomeric, and extracellular matrix proteins. These findings indicate that isolated LCA exerts limited endocrine disruption but may selectively compromise bone turnover and muscle anabolic response, suggesting that without acute LEA, LCA has limited influence on muscle oxidative phenotype.

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PubMed2026

Comparative analysis of histological and transcriptomic characteristics in caudal muscles of nile crocodiles (Crocodylus niloticus), siamese crocodiles (Crocodylus siamensis), and their hybrids.

Crocodylus niloticus and Crocodylus siamensis are high-value aquaculture species. C. niloticus is large-bodied but less abundant, while C. siamensis grows fast but is small-sized. Their hybrids combine parental advantages, yet relevant research is scarce. This study compared the histological and transcriptomic characteristics of the caudal muscle across the three taxa. HE staining indicated that C. niloticus had significantly larger myofiber diameters (p < 0.05); C. siamensis had the smallest, and the myofiber density of hybrids was much closer to that of C. siamensis. Masson's trichrome staining indicated that C. niloticus had the thickest collagen fibers (p < 0.05), C. siamensis the thinnest, and hybrids exhibited highly similar histological traits to C. siamensis. C. niloticus had higher LDH and SDH activities in caudal muscles, whereas the hybrid crocodile indicated the highest CK activity. Transcriptomic analysis identified numerous differentially expressed genes (DEGs), which were enriched in growth, muscle metabolism, and energy allocation pathways via GO/KEGG annotations. PPI analysis screened 24 hub genes related to energy metabolism. This study systematically reveals caudal muscle differences, providing insights into growth-related molecular mechanisms and theoretical support for crocodile artificial breeding.

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PubMed2026

The effects of nitrate and nitrite supplementation on mitochondrial respiration in permeabilized muscle fibres in young healthy adults.

Nitric oxide (NO) is a direct regulator of mitochondrial respiration. Nitrate (NO3-) and nitrite (NO2-) are good sources of NO, but whether their effects on mitochondrial respiration differ between in vivo and in vitro administration remains unclear. In Study 1, 8 participants consumed NO3- -rich beetroot juice (BR) (∼12.8 mmol NO3-) and NO3- -depleted placebo beetroot juice (PL) (∼0.08 mmol NO3-) acutely and chronically for 2 weeks in a randomised, double-blind, crossover design. A substrate-uncoupler-inhibitor titration (SUIT) protocol was used to assess mitochondrial respiration using high-resolution respirometry (oxygen tension: ∼200-450 μM) in permeabilized muscle fibres. In Study 2, skeletal muscle samples were collected from 11 participants. In a randomised, crossover design, different doses (0, 1.5, and 3.0 μM) of sodium nitrite (NaNO2) were administered to permeabilized muscle fibres. Mitochondrial respiration was measured using the same SUIT protocol under lower oxygen tension (∼50-200 μM). Although muscle NO3- concentration significantly increased after both acute and chronic BR supplementation, mitochondrial respiration and exercise performance did not differ between PL and BR in either condition. Similarly, absolute oxygen flux across different respiratory states were not different between different doses of NaNO2. However, the leak control ratio, reflecting the degree of uncoupling of mitochondrial respiration, was significantly higher with 3.0 μM NaNO2 administration (0.12 ± 0.05) compared to 0 μM NaNO2 administration (0.09 ± 0.04, P = 0.03). These findings, involving both in vivo and in vitro administration approaches, albeit in the presence of relatively high oxygen concentrations, suggest that neither NO3- nor NO2- improves mitochondrial respiration, at least in young healthy adults.

Humans↗

PubMed2026

Application of 13C MRS demonstrates carbohydrate feeding spares muscle but not liver glycogen utilization during high-intensity interval exercise.

We examined liver and muscle glycogen utilization during high-intensity interval cycling, and the impact of carbohydrate (CHO) feeding, using noninvasive 13C magnetic resonance spectroscopy (MRS). Following 24 h of standardized dietary intake, nine male cyclists completed 8 × 5-min intervals (1-min recovery), ingesting either placebo (PLA), 60 g maltodextrin (CHO), or 60 g maltodextrin plus caffeine, taurine, l-theanine, l-citrulline, and citicoline (CHO+) in a randomized crossover design. 13C MRS and 1H imaging were performed pre- and postexercise to determine liver and muscle glycogen and liver volume, respectively. Liver glycogen utilization was not significantly different between trials (P = 0.101) despite lower postexercise plasma glucagon concentrations in CHO and CHO+ (P = 0.001). In contrast, muscle glycogen utilization was significantly lower (∼40%) with CHO feeding compared with PLA (P = 0.006), yet this sparing effect was not evident with CHO+ (P = 0.073) in accordance with a higher mean power output during the late intervals (+2.8%, P = 0.046). Plasma glucose was comparable between trials (P = 0.175), whereas plasma lactate was higher in CHO+ versus CHO (P = 0.003), alongside lower blood bicarbonate (P = 0.005), base excess (P < 0.001), and total CO2 (P = 0.004). These findings demonstrate preferential use of skeletal muscle glycogen during high-intensity interval training (HIIT), which is attenuated under conditions of CHO feeding. This sparing effect is, however, not evident with the coingestion of a caffeine-containing multi-ingredient blend, potentially due to an increased capacity to sustain higher power outputs resulting in greater glycogen utilization.NEW & NOTEWORTHY Using 13C MRS, we provide data demonstrating preferential use of skeletal muscle glycogen during HIIT. Furthermore, data show muscle glycogen utilization is attenuated with CHO feeding, yet sparing is not evident when coingesting a caffeine-containing formulation, potentially reflecting increased capacity to perform more total work rather than a direct metabolic effect of caffeine. In contrast, liver glycogen utilization was not significantly different with CHO feeding despite a modest reduction of ∼5 g versus placebo.

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PubMed2026

Comparative effects of 12-week resistance training on unstable and stable surfaces on muscle stiffness, muscle co-activation, and balance in older patients with knee osteoarthritis.

OBJECTIVE: This randomized trial compared the effects of unstable resistance training (URT), involving resistance exercises on unstable surfaces, and stable resistance training (SRT), performed on stable surfaces, on muscle stiffness, co-activation, and balance in older adults with knee osteoarthritis (KOA). We hypothesized that URT would yield greater improvements by enhancing neuromuscular adaptability. METHODS: Fifty patients with KOA were randomly assigned to the URT group (n = 25) or the SRT group (n = 25). After attrition, 46 participants (URT: n = 23; SRT: n = 23) completed the intervention and were included in the final analysis. Both groups completed a 12-week supervised lower-limb resistance training program (3 sessions/week) consisting of 10 exercises performed under either unstable or stable support conditions. RESULTS: After 12 weeks of intervention, both groups showed significant reductions in pain intensity (p < 0.001). However, compared with the SRT group, the URT group demonstrated significantly greater reductions in quadriceps stiffness (p < 0.05), selected hamstring stiffness outcomes (p < 0.05), and quadriceps-hamstring co-activation (p < 0.001), alongside superior improvements in both dynamic balance and static balance (all p < 0.05). CONCLUSION: While both training modalities are effective for pain relief, URT elicited greater improvements in balance-related performance and neuromuscular-mechanical outcomes than SRT in older adults with KOA. These findings suggest that incorporating unstable support conditions into resistance training may provide additional rehabilitation benefits for this population.

Humans↗

PubMed2026

Effects of rumen fluid transplantation on longissimus dorsi muscle development in Xizang sheep: An association analysis based on transcriptomic and serum metabolomic profiles.

This study aimed to investigate the effects of rumen fluid transplantation (RFT) on the growth and development of the longissimus dorsi muscle in female Xizang sheep. After RFT, muscle lightness differed significantly between the two groups, with the LDC group showing significantly higher lightness than the LDT group. In contrast, no significant differences were observed between groups in other muscle phenotypic traits, including drip loss, pH, cooking loss, shear force, redness, and yellowness. Antioxidant-related indices (SOD, GSH-PX, MDA, CAT, and T-AOC) also showed no significant differences between groups. Histological analysis revealed that muscle fiber length, width, and density were significantly greater in the experimental group than in the control group. Transcriptomic analysis identified 515 differentially expressed genes (DEGs), of which 419 were downregulated. KEGG analysis indicated that genes involved in muscle development-related pathways, such as cell adhesion and the PI3K-Akt signaling pathway, were predominantly downregulated. Key serum metabolites (L-kynurenine, IPA, allantoin, and propionylcarnitine) showed highly significant positive correlations with muscle fiber growth indices. In contrast, metabolites such as l-carnitine, acetylcarnitine, and citrulline were negatively correlated with muscle fiber growth, but positively correlated with the expression of muscle structure-related genes (COL11A1 and EFNA5) and with meat lightness. Overall, this study provides new insights into the potential molecular basis by which RFT influences muscle growth and development. However, the mechanisms by which RFT affects muscle development and meat quality-related traits remain unclear and warrant further investigation.

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PubMed2026

Effect of Motor-Control Exercises on Scapulohumeral and Scapulothoracic Muscle Activations in Athletes With Secondary Subacromial Impingement Syndrome.

CONTEXT: Unbalanced or uncoordinated activity across either the scapulohumeral or the scapulothoracic muscle may impair scapulohumeral rhythm during arm elevation. OBJECTIVE: To compare the effects of progressive resistance exercises (PREs), integrated with and without facilitatory motor-control exercises (MCEs), on scapulohumeral and scapulothoracic myoelectric activities in overhead athletes diagnosed with secondary subacromial impingement syndrome (SAIS). DESIGN: Randomized controlled clinical trial. SETTING: Neuromuscular Rehabilitation Research Center. PATIENTS OR OTHER PARTICIPANTS: Overhead athletes diagnosed with secondary SAIS were assigned randomly to 3 parallel groups: 2 intervention groups and 1 control group. INTERVENTIONS: All groups received contemporary physical therapy modalities every other day for 8 weeks. Intervention groups I and II also completed scapulohumeral and scapulothoracic PREs, integrated, respectively, with and without facilitatory MCEs targeting infraspinatus and lower trapezius muscles. MAIN OUTCOME MEASURES: Scapulohumeral and scapulothoracic myoelectric activities were recorded during scapular arm abduction between 80° and 110° before and after the prescribed treatment protocols. RESULTS: Scapulohumeral and scapulothoracic PREs reduced the corresponding myoelectric activities during scapular arm abduction within the groups (P ≤ .02, partial η2 ≥ 0.127). Facilitatory biofeedback-guided exercises integrated into PREs preserved scapulohumeral and scapulothoracic myoelectric activities (P ≤ .03), excluding teres minor myoelectric activity (P > .99). CONCLUSIONS: Scapulohumeral and scapulothoracic PREs reduced the corresponding muscle activations during scapular arm abduction in overhead athletes with secondary SAIS. Facilitatory MCEs targeting infraspinatus and lower trapezius muscles, integrated into PREs, preserved scapulohumeral and scapulothoracic muscle activations.

Humans↗

PubMed2026

Muscle mechanical and architectural adaptations in response to different endurance training modalities in older adults.

INTRODUCTION: This study examined the effects of various cycling endurance training modalities, matched for total workload, on muscle mechanical and architectural characteristics in older adults. METHODS: Fifty healthy participants (25 females, 59-79 yrs) were randomly assigned to five age and sex matched groups: one control and four workload-matched training groups (moderate-intensity continuous, heavy-intensity continuous, high-intensity interval, and heavy-intensity continuous in eccentric cycling). Training consisted of three weekly sessions over 8 weeks, with evaluations conducted at the beginning and end of the intervention with maximal voluntary isometric contractions at five different knee angles (90, 75, 60, 45, 30°) and maximal concentric and eccentric isokinetic contractions at five different knee angular velocities (45, 90, 150, 210, 250°/s). Maximum voluntary isometric torque (Tmax) and optimal knee angle (KAopt) were obtained from the isometric contractions; eccentric torque (Tecc) and maximum concentric knee angular velocity (Vmax) were obtained from the isokinetic contractions. The muscle architecture of vastus lateralis (VL) at rest (muscle thickness, pennation angle, and fascicle length) was investigated as well. RESULTS: No statistical differences were detected between groups or time points in VL architecture, in KAopt and in Vmax. A main effect of time was observed for Tmax (p < 0.001, η2p = 0.458) and Tecc (p = 0.002, η2p = 0.191) in all the investigated training groups. The within-group comparisons indicate significant increases in Tmax in the training groups, but not in the control group. CONCLUSIONS: Commonly applied endurance exercises improve muscle mechanical capacity (Tmax and Tecc) in older adults, with no structural (architectural) muscle remodelling, when matched for workload.

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PubMed2026

The impact of acute sleep fragmentation on muscle blood flow responses to handgrip exercise.

Sleep fragmentation is reported to impair resting vascular function. The aim of this study was to test the hypothesis that acute sleep fragmentation would impair muscle blood flow during exercise. Twenty adults (10 females and 10 males) participated in a randomized crossover study that included one night of habitual sleep and one night of fragmented sleep. Sleep was assessed at home using wrist actigraphy. Arousals from sleep were increased by an audio alarm sounding every 30 min. The morning following each sleep condition, participants performed single handgrip contractions and rhythmic handgrip exercise at 15%, 30%, and 45% MVC. Forearm blood flow (FBF) was measured using Doppler ultrasound. Nightly awakenings and wake after sleep onset significantly increased by 18% and 43%, respectively, after fragmented sleep, leading to lower sleep duration (P < 0.001). Peak FBF and total hyperemic responses following single contractions were similar between sleep conditions (all P > 0.05). During rhythmic handgrip exercise, brachial artery dilation was reduced after fragmented sleep (main effect: 5.5 ± 4.8 vs. 3.3 ± 3.7%; P = 0.01), leading to a lower FBF response to rhythmic exercise (main effect: 122 ± 58 vs. 110 ± 56 mL/min; P = 0.04). Endothelial sensitivity to shear rate was similar between sleep conditions (habitual vs. fragmented: 0.039 ± 0.024 vs. 0.042 ± 0.031%/s-1; P = 0.77). In summary, acute sleep fragmentation decreases skeletal muscle blood flow during exercise. This finding suggests that blunted oxygen delivery may be a contributing factor for exercise performance deficits after disturbed sleep.NEW & NOTEWORTHY We demonstrate that one night of fragmented sleep decreases steady-state blood flow and vascular conductance during low- to moderate-intensity handgrip exercise. This impairment was not due to an impaired rapid vasodilation to single contractions nor altered endothelial sensitivity to shear rate as these variables were unchanged after acute sleep fragmentation. These results reveal a negative impact of disrupted sleep on the steady-state muscle vasodilatory response to rhythmic contractions.

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PubMed2026

Multi‑omics approaches to decipher the molecular mechanisms of exercise‑mediated bone protection: From mechanistic insights to personalized exercise prescription (Review).

The global burden of bone metabolic disorders necessitates a shift from generic exercise recommendations toward personalized prescription strategies. Exercise confers skeletal protection through mechanotransduction, yet the underlying molecular networks remain incompletely understood. Multi‑omics technologies, including transcriptomics, proteomics, metabolomics and single‑cell spatial approaches, have revolutionized the capacity to decode exercise‑mediated bone adaptation at the systems level. The present review synthesizes current single‑omics landscapes and integrative multi‑omics analyses that elucidate the core regulatory networks, mechanobiological coupling mechanisms and multiorgan crosstalk that are implicated in the bone response to mechanical loading. Translational applications across clinical scenarios such as osteoporosis, osteoarthritis and disuse bone loss are evaluated, and the technical, analytical and translational challenges limiting clinical implementation are addressed. Finally, the present review provides a framework for translating multi‑omics molecular signatures into personalized exercise prescriptions for optimized skeletal health.

Humans↗

PubMed2026

Responsiveness of muscle mass gain to different load intensities of resistance training in older women: A randomized crossover study.

BACKGROUND: Aging is associated with progressive declines in skeletal muscle mass (SMM) and substantial interindividual variability in adaptations to resistance training (RT). However, whether training load intensity influences hypertrophic responsiveness in older adults remains unclear. OBJECTIVE: To investigate the effects of two commonly prescribed RT loading schemes (15RM and 10RM) on estimated SMM adaptations and responsiveness in older women. METHODS: Twenty-seven older women (67.7 ± 4.9 years; 65.7 ± 10.6 kg; 154.5 ± 5.8 cm) completed two 8-week RT interventions performed at 15RM and 10RM in a randomized crossover design, separated by a 12-week detraining period. Estimated SMM was assessed using dual-energy X-ray absorptiometry. Responsiveness was operationally defined using the standard error of measurement, and participants were classified as responders (RP) or non-responders (N-RP) according to changes in estimated SMM. RESULTS: Both loading schemes promoted significant and comparable increases in estimated SMM (15RM: +0.62 ± 0.4 kg vs. 10RM: +0.43 ± 0.3 kg). Overall, 61.1% of participants were classified as responders in at least one condition, whereas 38.9% were classified as non-responders. Responsiveness status was consistent across conditions for most participants, with 48.1% classified as responders under both loading schemes and 25.9% as non-responders under both conditions. Only seven participants (25.9%) changed responsiveness status between interventions. No clear pattern indicated a greater likelihood of responsiveness with either loading scheme. CONCLUSIONS: Results suggest that both the 10RM and 15RM RT protocols significantly increase estimated SMM in older women, with no significant differences between training conditions. Although substantial interindividual variability in adaptive responses exists, training load intensity does not appear to meaningfully influence responsiveness status in most individuals. These findings suggest that both loading schemes can be effectively prescribed to promote SMM gains in older women.

Aged↗