bims-ensmum 2026-08-16 papers

bims-ensmum

Biomed News

on Exercise and nutrition in skeletal muscle metabolism

Issue of 2026–08–16
nine papers selected by
Rachel M. Handy, University of Guelph and Universiteit Mastricht

Application of 13C MRS demonstrates carbohydrate feeding spares muscle but not liver glycogen utilisation during high-intensity interval exercise.
Aging preserves mTORC1 but attenuates JNK-SMAD2L signaling sensitivity to passive stretch-induced tension development in isolated mouse skeletal muscle.
Interleukin-1 signaling contributes to endurance training-induced skeletal muscle adaptations.
Muscle mass and quality by computed tomography predicts mortality and emergency department revisits in older adults with acute pulmonary embolism.
Changes in Muscle Mass and Quality Mediate the Effect of High-Calorie Intake on Clinical Outcomes.
High animal protein and high plant protein meals differentially alter postprandial plasma amino acid concentrations but not glucose homeostasis in people with overweight/obesity in a randomized, cross-over, single-meal study.
Nutritional Strategies for Recovery-Adaptation Coupling After Exercise: From Muscle Damage to Performance Remodeling.
Effects of creatine supplementation with and without exercise and diet intervention on body composition, cognitive function, and markers of health in middle-aged and older adults.
Effects of exercise and nutritional interventions on muscle-specific strength in older adults: A systematic review and meta-analysis.

Am J Physiol Endocrinol Metab. 2026 Aug 04.

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

Sophie C Hannon, Libby Henthorn, Jay Vadher, Catharine Montgomery, George F Pavis, Francis B Stephens, Benjamin T Wall, Nathan Hodson, James P Morton, Aneurin J Kennerley, Mark A Hearris.

  We examined liver and muscle glycogen utilisation during high-intensity interval cycling, and the impact of carbohydrate (CHO) feeding, using non-invasive 13C magnetic resonance spectroscopy (MRS). Following 24 h of standardised dietary intake, nine male cyclists completed 8 x 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 randomised crossover design. 13C MRS and 1H imaging were performed pre- and post-exercise to determine liver and muscle glycogen and liver volume, respectively. Liver glycogen utilisation was not significantly different between trials (P = 0.101) despite lower post-exercise plasma glucagon concentrations in CHO and CHO+ (P = 0.001). In contrast, muscle glycogen utilisation was significantly lower (~40%) with CHO feeding compared to 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+ vs 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 HIIT, which is attenuated under conditions of CHO feeding. This sparing effect is, however, not evident with the co-ingestion of a caffeine containing multi-ingredient blend, potentially due to an increased capacity to sustain higher power outputs resulting in greater glycogen utilisation.

Keywords:  13C magnetic resonance spectroscopy; HIIT; exercise; glycogen; liver

DOI:  https://doi.org/10.1152/ajpendo.00139.2026
Exp Gerontol. 2026 Aug 04. pii: S0531-5565(26)00244-5. [Epub ahead of print]223 113265

Aging preserves mTORC1 but attenuates JNK-SMAD2L signaling sensitivity to passive stretch-induced tension development in isolated mouse skeletal muscle.

Jonas Boritz Kristiansen, Jacob Andresen, Jesper Emil Jakobsgaard, Kristian Vissing.

   INTRODUCTION: Aging is associated with impaired skeletal muscle mass and function, often attributed to reduced sensitivity to anabolic stimuli. This study investigated whether aging influences the sensitivity of key anabolic signaling pathways to mechanical tension development in skeletal muscle.
METHODS: Using an ex vivo model, extensor digitorum longus (EDL) muscles from adult (16 weeks) and old (24 months) female mice were subjected to a standardized passive stretch protocol, with contralateral muscles serving as controls. During recovery, phosphorylation of proteins related to downstream mTORC1 and JNK-SMAD2-L signaling were assessed by immunoblotting.
RESULTS: Passive stretch significantly increased phosphorylation of mTORC1-related proteins (mTOR, p70S6K, rpS6, and 4E-BP1) in both adult and old muscles, with no significant differences between age groups, indicating preserved mTORC1 signaling sensitivity to mechanical tension with aging. In contrast, the magnitude of activation of JNK and SMAD2-L signaling was attenuated in old muscles.
DISCUSSION: Our findings reveal that mechanosensitive anabolic signaling is differentially affected by aging. While the intrinsic capacity for mTORC1 activation in response to mechanical tension appears to be preserved with aging, JNK-SMAD2L signaling exhibits reduced mechanosensitivity in aged muscle. This divergence suggests that aging selectively impairs tension-sensitive transcriptional pathways, potentially constraining muscle remodeling despite preserved translational signaling capacity. These findings further imply that age-related deficits observed in vivo may, at least in part, arise from systemic influences rather than intrinsic defects adhering to mTORC1 mechanotransduction.

Keywords:  Aging; Anabolic signaling; Ex vivo; JNK; Mechanotransduction; Passive stretch; SMAD; Skeletal muscle; mTORC1

DOI:  https://doi.org/10.1016/j.exger.2026.113265
Am J Physiol Regul Integr Comp Physiol. 2026 Aug 09.

Interleukin-1 signaling contributes to endurance training-induced skeletal muscle adaptations.

Azuma Naito, Tatsuya Sato, Nao Tokuda, Nao Yamauchi, Ayaka Niibori, Kazuma Okada, Takashi Yamada.

  Interleukin (IL)-1 is widely recognized as an inflammatory cytokine induced in response to muscle injury, where it contributes to the clearance of damaged fibers and supports subsequent regenerative and reparative processes. In contrast, IL-1 derived from infiltrating neutrophils in response to transient, non-damaging exercise has been reported to regulate energy metabolism during endurance exercise. Therefore, in the present study, we investigated the role of IL-1 in skeletal muscle endurance adaptations induced by chronic endurance training (ET). Thirteen-week-old BALB/c wild-type (WT) mice and mice deficient in both IL-1α and IL-1β (IL-1 knockout; IL-1 KO) were used. The left hindlimb was subjected to ET induced by electrical stimulation of the triceps surae muscle three times per week for five weeks, while the right hindlimb served as a control. Baseline muscle endurance did not differ between WT and IL-1 KO mice. Following ET, muscle endurance and mitochondria respiration were significantly increased in WT mice but not in IL-1 KO mice. Moreover, ET induced increases in citrate synthase activity and the expression of PGC-1α, mitochondrial respiratory chain complexes I and III, and hexokinase 2 exclusively in WT mice. A single bout of exercise significantly increased IL-1β mRNA, but not IL-1α mRNA, in WT mice. In addition, exercise-induced phosphorylation of p38 MAPK and increases in PGC-1α-b and hexokinase 2 mRNA expression were attenuated in IL-1 KO mice. These findings suggest that IL-1 signaling is associated with ET-induced improvements in muscle endurance and mitochondrial quantity and quality, possibly through activation of the p38 MAPK pathway.

Keywords:  endurance training; interleukin-1; mitochondrial adaptations; p38 MAPK; skeletal muscle

DOI:  https://doi.org/10.1152/ajpregu.00125.2026
J Thromb Thrombolysis. 2026 Aug 11.

Muscle mass and quality by computed tomography predicts mortality and emergency department revisits in older adults with acute pulmonary embolism.

Victoria Hayman, Emilie Groulx-Boivin, Bojan Kovacina, Marc Afilalo, Jonathan Afilalo.

  Sarcopenia, the age-related loss of muscle mass and quality, is an indicator of frailty that can be objectively measured using computed tomography (CT) images acquired for other routine indications. CT-based muscle mass has been shown to predict adverse outcomes in many diseases, although evidence in acute pulmonary embolism (PE) is scant. A retrospective cohort study included patients ≥ 70 years diagnosed with acute PE between 2015 and 2019. Axial CT images at the carina and mid-thigh were used to measure chest muscle area (CMA), thigh muscle area (TMA), and thigh intramuscular fat area (TFMA) using semi-automated segmentation tools. Outcomes included 30-day mortality or unplanned emergency department (ED) revisit, hospital length of stay, disposition, and mortality at last follow-up. Logistic and Cox regression models were adjusted for the Pulmonary Embolism Severity Index (PESI). The cohort consisted of 205 patients (mean age 80 years; 63% females), with high-risk characteristics shown by a mean PESI score of 114. The incidence of 30-day mortality or ED revisit was 32%, 18%, and 12% in patients with low, intermediate, and high CMA, respectively (p = 0.01). CMA, TMA, and TFMA were independently and incrementally predictive of 30-day mortality or ED revisit, while CMA also predicted long-term mortality over 2 years. Patients with low muscle mass were more likely to have prolonged hospitalization and less likely to be discharged home. Muscle mass and quality can be opportunistically assessed from clinical CT scans and used to improve risk stratification and individualize decision-making in older adults with acute PE.

Keywords:  CT; Mortality; Muscle mass; Predictors; Pulmonary embolism; Sarcopenia

DOI:  https://doi.org/10.1007/s11239-026-03357-6
J Cachexia Sarcopenia Muscle. 2026 Aug;17(4): e70355

Changes in Muscle Mass and Quality Mediate the Effect of High-Calorie Intake on Clinical Outcomes.

Yassir Aarab, Fabrice Raynaud, Mathieu Capdevila, Aurelien Flatres, Gérald Hugon, Céline Lauret, Nicolas Molinari, Celia Vidal, Kada Klouche, Samir Jaber, Stefan Matecki, Boris Jung.

   BACKGROUND: Critically ill patients frequently experienced acquired muscle dysfunction, which adversely affects outcomes. The relationship between calorie intake, muscle dysfunction and outcomes remains unclear. This study aims to determine if early calorie intake affects patients' outcomes through changes in skeletal muscle mass or quality, and to explore changes in muscle structure and underlying molecular pathways using limb muscle biopsies in a piglet model.
METHODS: This translational study combines data from a prospective observational study including critically ill patients and a 72-h ventilated piglet model with early high calorie full enteral nutrition, both recording serial ultrasound measurements of limb muscle thickness and stiffness. Patients were classified into two trajectory groups based on thickness, stiffness and calorie intake. Adjusted mediation analysis quantified the effect of calorie intake on outcomes explained by muscle trajectories. The primary endpoint was ventilator-free days at Day 28 (VFD28). In vivo limb muscle biopsies from piglets were analysed.
RESULTS: Among 102 patients, 21% and 28% exhibited decreased thickness and stiffness by Day 7, respectively; 36% received high-calorie intake at Day 7. Patients categorized into the 'decreased trajectory group' for both thickness and stiffness showed lower VFD28 (p < 0.01) and longer ICU stay (p < 0.01) compared to the 'stable trajectory group'. High-calorie intake was associated with significantly lower VFD28 (-8.7 days [-14.7 to -1.7]; p = 0.01), longer ICU stay (p < 0.01) and higher ICU mortality (p < 0.01). Decreased muscle trajectories mediated, respectively, 42% and 28% of the association between high-calorie intake and VFD 28. The porcine model showed a limb muscle stiffness reduction associated with muscle fibre atrophy and increased intramuscular lipid content linked to decreased protein synthesis (IGF-1 and myostatin downregulation), increased autophagy (ATG5, ATG7 and P62 increased activity) and impaired fatty acid metabolism (carnitine palmitoyltransferase 1B reduced expression).
CONCLUSIONS: This study demonstrates that early calorie intake in critically ill patients adversely affects muscle mass and quality, mediating negative outcomes. The porcine model helps elucidate underlying mechanisms, with early high-calorie intake resulting in a metabolic oversupply state associated with metabolic disorders leading to muscle fibre atrophy and lipid accumulation. These results highlight the importance of targeted nutritional strategies to preserve muscle health in critically ill patients.

Keywords:  critical illness; elastography; nutrition; outcomes; skeletal muscle; ultrasound

DOI:  https://doi.org/10.1002/jcsm.70355
Am J Clin Nutr. 2026 Aug 10. pii: S0002-9165(26)00277-7. [Epub ahead of print] 101468

High animal protein and high plant protein meals differentially alter postprandial plasma amino acid concentrations but not glucose homeostasis in people with overweight/obesity in a randomized, cross-over, single-meal study.

Alan Fappi, Vasavi Shabrish, Hunter Hollomon, Tanhaul Islam, Xiangyu Zhang, Babak Razani, Samuel Klein, Bettina Mittendorfer.

   BACKGROUND: In population studies, high protein, particularly high animal protein, intake is associated with an increased risk of developing type 2 diabetes. Results from preclinical studies suggest this association might be mediated by branched-chain and other essential amino acids.
OBJECTIVE: Interrogate putative mechanisms linking high protein intake and diabetes risk.
METHODS: We conducted a randomized, cross-over, single-meal study in people with overweight/obesity to compare the effects of a standard meal (∼18 g protein/15% meal energy) and high protein meals (∼28 g protein/22% meal energy) enriched with protein from either animal (n=21) or plant (n=21) sources on postprandial plasma amino acid, glucose, and key glucoregulatory hormone concentrations (180-min area-under-the-curve).
RESULTS: Postprandial plasma amino acids were higher after the high-protein meals than the standard (STD) meal, with greater increases (all p<0.05) after the high animal protein (HAP) than the high plant protein (HPP) meal in total essential (HAP vs STD, 28±3%; HPP vs STD, 19±3%; mean±SEM) and total branched-chain (HAP vs STD, 36±3%; HPP vs STD, 24±3%), but not total (all) amino acids. Compared with the STD meal, both the HAP and HPP meals resulted in lower plasma glucose (HAP vs STD, -4.3±2.1%; HPP vs STD, -5.2±1.5%) and higher glucagon (HAP vs STD, 48±12%; HPP vs STD, 44±13%), glucagon-like peptide 1 (HAP vs STD, 23±6%; HPP vs STD, 30±12%), and insulin in relationship to glucose, without differences between the HAP and HPP meals.
CONCLUSIONS: Both the amount and type of protein are determinants of postprandial plasma amino acid concentrations, but only the amount, not the type of protein is a determinant of plasma glucoregulatory hormone and glucose concentrations. Therefore, essential and branched-chain amino acids are not important regulators of postprandial glucose homeostasis. Non-protein dietary or non-dietary factors likely mediate differential effects of high animal and high plant protein intake on glucose metabolism.
CLINICALTRIALS: gov, numbers: NCT03994367 and NCT05235464.

Keywords:  amino acids; branched-chain amino acids; diet; fibroblast growth factor 21; glucagon; glucose; high-protein; insulin; insulin secretion

DOI:  https://doi.org/10.1016/j.ajcnut.2026.101468
Nutrients. 2026 Aug 04. pii: 2523. [Epub ahead of print]18(15):

Nutritional Strategies for Recovery-Adaptation Coupling After Exercise: From Muscle Damage to Performance Remodeling.

Dan Cristian Mănescu, Giuseppe Cerullo, Cristian Petri, Costin Petcu, Radu Bidiugan, Andreea Voinea, Simona Bidiugan, Alexandra Reta Iacobini, Andrei Dragomir, Alexandru Adrian Gavrilă, Răzvan Alexandrescu, Cristian Băltărețu, Răzvan Liviu Petre.

  Background/Objectives: Recovery nutrition must restore near-term readiness without indiscriminately suppressing biological signals that contribute to repair and training adaptation. This review evaluates recovery-adaptation coupling (RAC) as a research framework and clarifies its contribution relative to established recovery, nutrient-periodization, and athlete-monitoring models. Methods: Targeted narrative searches of PubMed/MEDLINE, Scopus, and Web of Science were supplemented by Google Scholar citation tracking and backward and forward screening. Peer-reviewed English-language literature available through 31 May 2026 was considered. Human athlete studies, randomized trials, systematic reviews, meta-analyses, consensus statements, and position stands were prioritized; mechanistic evidence was used to explain pathways rather than to support stand-alone performance recommendations. The final cited corpus comprised 130 records. No formal risk-of-bias tool, certainty grading, PRISMA denominator, or quantitative pooling was used. Claims were instead identified as established practice (EP), context-dependent evidence (CDE), mechanistic rationale (MR), or RAC hypothesis (RH). Results: The most consistent applied support concerns adequate energy availability, distributed high-quality protein, carbohydrate restoration when recovery windows are short, and individualized fluid and sodium replacement. Evidence for polyphenol-rich products, curcumin, omega-3 fatty acids, and creatine is context- and product-dependent. Collagen or gelatin evidence is mainly mechanistic or pilot-level, while RAC recovery-pattern categories and multimodal monitoring rules remain unvalidated hypotheses. RAC differs from existing frameworks by jointly specifying the next athletic demand, dominant recovery bottleneck, possible adaptive cost of intervention, and response-verification plan. Conclusions: RAC should presently be interpreted as an evidence-organization and hypothesis-generation architecture, not as a validated predictive, diagnostic, or treatment algorithm. Prospective comparative studies are required before RAC-specific decision rules can guide individualized practice.

Keywords:  delayed-onset muscle soreness; exercise-induced muscle damage; inflammation resolution; micronutrients; muscle protein synthesis; muscle recovery; oxidative stress; polyphenols; precision nutrition; recovery monitoring; sports nutrition

DOI:  https://doi.org/10.3390/nu18152523
J Int Soc Sports Nutr. 2026 Aug 21. 23(sup1): 2716273

Effects of creatine supplementation with and without exercise and diet intervention on body composition, cognitive function, and markers of health in middle-aged and older adults.

Jisun Chun, Yuhang Liu, Giuliet L Kibler, Hudson Lee, Khatereh Babakhani, Nathaniel Rhoades, Ian Bivins, Joungbo Ko, Broderick Dickerson, Drew E Gonzalez, Ryan J Sowinski, Chris J Rasmussen, Richard B Kreider.

   BACKGROUND: Theoretically, CrM supplementation during a weight loss and exercise intervention may help older individuals promote more optimal changes in body composition, training adaptations, and cognition. To determine whether CrM affects body composition, cognitive function, and/or markers of health in untrained and trained middle-aged and older adults.
METHODS: Seventy-three healthy sedentary adults selected whether to participate in a non-exercise or exercise and diet intervention and were then randomized, in a double-blind and counterbalanced manner, to 2 × 5 g/d of maltodextrin placebo (PLA) or CrM. Sixty-four adults aged 45-65 years (54.5 ± 6.2 years, 84.5 ± 21.3 kg; 40 females and 24 males) completed the 12-week intervention and were analyzed. At 0, 6, and 12 weeks, participants had DXA body composition determined, donated fasting blood samples, and completed a battery of cognitive tests and questionnaires. general linear models (GLMs), multivariate and univariate, with repeated measures and mean changes from baseline with 95% confidence intervals, and Chi-squared analyzes were used.
RESULTS: CrM supplementation without exercise training and diet intervention increased lean tissue mass, strength, and muscular endurance while promoting favorable changes in selected blood lipids, HbA1c, and selected markers of cognitive function and memory. Creatine supplementation during an exercise and weight-loss diet intervention increased lean tissue mass, promoted a greater reduction in body fat percentage, and improved muscular strength, endurance, and selected markers of cognitive function and memory. Supplementation was well-tolerated.
CONCLUSION: CrM supplementation with and without exercise and diet intervention may help middle-aged and older adults maintain muscle mass and strength while favourably affecting selected markers of health and cognitive function. Individual cognitive and biomarker findings should be interpreted as exploratory. Clinical trial registration: ISRCTN83081058.

Keywords:  Memory; nootropic; recall; sarcopenia; vigilance; weight loss

DOI:  https://doi.org/10.1080/15502783.2026.2716273
Ageing Res Rev. 2026 Aug 08. pii: S1568-1637(26)00263-1. [Epub ahead of print] 103271

Effects of exercise and nutritional interventions on muscle-specific strength in older adults: A systematic review and meta-analysis.

Takahisa Ohta, Sho Hatanaka, Jiaqi Li, Kanae Furuya, Kaori Kinoshita, Rei Otsuka, Michiyo Kawamura, Yutaka Watanabe, Ko Matsudaira, Hiroyuki Oka, Yosuke Osuka.

   PURPOSE: Deficient muscle-specific strength has been recognized as a key component of sarcopenia. However, the impact of various interventions on muscle-specific strength has not been systematically reviewed. This study aims to provide a systematic summary of research examining the effects of exercise, nutrition, and other interventions on muscle-specific strength in older adults.
METHODS: Randomized controlled trials (RCTs) were identified through comprehensive searches of major databases. Eligible studies included adults aged 60 years or older, with interventions lasting at least 8 weeks. Studies were required to assess muscle strength normalized by muscle mass. Standardized mean differences (SMDs) were calculated using random-effects meta-analyses, and heterogeneity was evaluated using I² statistics.
RESULTS: A total of 41 RCTs with 3,141 participants were included in the analysis. Interventions included resistance exercise, nutritional supplementation, aerobic exercise, concurrent training, combined exercise and nutrition, caloric restriction, and other therapies. Resistance exercise significantly improved muscle-specific strength (SMD = 0.61, 95% confidence interval: 0.27 to 0.94), although heterogeneity was observed (I² = 81%). In contrast, interventions such as aerobic exercise, concurrent training, combined exercise and nutrition, and nutritional supplementation did not lead to significant improvements in muscle-specific strength. High heterogeneity was observed across all included studies.
CONCLUSIONS: Resistance exercise is the most effective intervention for improving muscle-specific strength in older adults. The effects of other interventions, such as nutritional supplementation and aerobic exercise, remain inconclusive. Further well-designed RCTs exploring diverse exercise regimens and nutritional interventions are needed to confirm these findings and identify the most effective strategies for enhancing muscle-specific strength in older populations.

Keywords:  muscle quality; randomized controlled trial; resistance exercise; sarcopenia

DOI:  https://doi.org/10.1016/j.arr.2026.103271