bims-ensmum 2026-09-06 papers

Am J Clin Nutr. 2026 Sep;pii: S0002-9165(26)00225-X. [Epub ahead of print]124(3): 101416

A self-selected vegan diet reduces skeletal muscle mass in healthy older adults: a randomized controlled trial.

Jacintha Domić, Pol Grootswagers, Philippe Jm Pinckaers, Max Melchers, Luc Jc van Loon, Lisette Cpgm de Groot.

BACKGROUND: Adopting a plant-based diet may compromise protein intake and impair skeletal muscle mass in older adults.
OBJECTIVES: To compare the impact of a 12-wk self-selected vegan diet with that of an omnivorous diet and a self-selected vegan diet with resistance exercise (RE) on skeletal muscle mass, strength, and muscle protein synthesis (MPS) rates in older adults.
METHODS: This randomized controlled trial included 3 parallel study arms in which 72 healthy older adults aged ≥65 y were randomly assigned to follow 1) a self-selected vegan diet (VEG), 2) their habitual omnivorous diet (OMNI), or 3) a self-selected vegan diet with RE (VEG-RE). At baseline and after 12 wk, thigh muscle volume, thigh muscle fat infiltration, and body fat distribution were assessed using magnetic resonance imaging, appendicular lean mass with dual x-ray absorptiometry, and muscle strength via Biodex. MPS rates were assessed during the first 10 d using a deuterium oxide protocol. Other outcome measures were body mass, dietary intake, and physical activity. Linear mixed models were applied to test differences between VEG and the other groups. Results are presented as estimated marginal mean or change in estimated marginal mean [95% confidence interval (CI)].
RESULTS: VEG reduced protein intake with ‒27.7 g/d (95% CI: ‒37.3, ‒18.2 g/d), ‒22.0 g/d (95% CI: ‒31.7, ‒12.4 g/d), and ‒19.3 g/d (95% CI: ‒29.2, ‒9.37 g/d) in weeks 1, 6, and 12 (all P < 0.0001 compared with baseline), which was similar to the decrease in VEG-RE (P > 0.05), but different from OMNI (P < 0.0001), in which protein intake did not change. Thigh muscle volume and appendicular lean mass significantly reduced in VEG [‒0.61 L (95% CI: ‒0.72, ‒0.50 L); ‒1.15 kg (95% CI: ‒1.46, ‒0.85 kg)] compared to OMNI [‒0.01 L (95% CI: ‒0.11, 0.09 L); +0.05 kg (95% CI: ‒0.23, 0.32 kg); both P < 0.0001] and VEG-RE [‒0.35 L (95% CI: ‒0.47, ‒0.24 L), P = 0.0038; ‒0.62 kg (95% CI: ‒0.93, ‒0.32 kg), P = 0.0033]. MPS was lower in VEG [1.09 %/d (95% CI: 1.01, 1.17 %/d)] compared with OMNI [1.27 %/d (95% CI: 1.18, 1.35 %/d); P = 0.0073] and VEG-RE [1.24 %/d (95% CI: 1.16, 1.33 %/d); P = 0.0246].
CONCLUSIONS: A self-selected vegan diet reduces protein intake, skeletal muscle mass, and MPS in older adults. The negative impact of a vegan diet on skeletal muscle mass can be mitigated by RE. This trial was registered at clinicaltrials.gov as NCT05809466. (https://clinicaltrials.gov/study/NCT05809466).

Keywords: aging; animal-based food; muscle; omnivorous; plant-based food; protein; protein quality; sarcopenia; vegan

DOI: https://doi.org/10.1016/j.ajcnut.2026.101416

Function (Oxf). 2026 Sep 03. e0222026

Evidence that myoglobin PO2 is a non-invasive measure of in vivo skeletal muscle mitochondrial PO2 during exercise in humans.

Ryan M Broxterman, Bradley A Ruple, Peter D Wagner, Russell S Richardson.

Muscle mitochondrial partial pressure of oxygen (PmitoO2) is a key determinant of skeletal muscle oxygen consumption (V̇O2), metabolism, gene regulation, and adaptation in health and disease. Yet PmitoO2 remains difficult to measure directly in vivo in humans during exercise. Myoglobin-associated PO2 (PMbO2), measured non-invasively using proton magnetic resonance spectroscopy, may provide a measure of PmitoO2 during maximal exercise in humans because Mb is coupled to mitochondrial oxygen availability and PMbO2 falls in the low PO2 range expected for PmitoO2 in vivo. However, it remains unknown whether PMbO2 during maximal exercise varies systematically with muscle V̇O2max, as would be expected if PMbO2 reflects PmitoO2 in vivo. We analyzed data from five initially sedentary males before and after 8 weeks of single-leg knee-extensor exercise (KE) training. During maximal KE under 0.12, 0.21, and 1.00 fractions of inspired oxygen (FIO2), we measured PMbO2 using myoglobin desaturation measured by proton magnetic resonance spectroscopy and muscle V̇O2max from leg blood flow and the arterial-femoral venous O2 content difference. Across FIO2 conditions, muscle V̇O2max varied systematically with PMbO2 both before and after training, consistent with O2-dependent mitochondrial respiration. When interpreted within a canonical hyperbolic framework, the V̇O2-PMbO2 relationship yielded low apparent mitochondrial P50 values that were broadly consistent with values reported for human skeletal muscle isolated mitochondria studied in vitro. A complementary linear P50 analysis that did not assume a hyperbolic relationship supported the same interpretation. Together, these findings provide data-supported, proof-of-concept evidence that PMbO2 reflects in vivo PmitoO2 during maximal exercise in humans.

Keywords: 1H-MRS; Maximal Oxygen Uptake; Mitochondria; Skeletal Muscle.

DOI: https://doi.org/10.1152/function.022.2026

FASEB J. 2026 Sep 15. 40(17): e72204

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

Erick Mosquera-Lopez, Harry L Taylor, Yusuke Nishimura, Carl Langan-Evans, Sam O Shepherd, Juliette A Strauss, James P Morton, Jatin G Burniston, Jose L Areta.

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.

Keywords: dietary periodisation; energy deficit; low‐carbohydrate high‐fat diet; muscle proteomics

DOI: https://doi.org/10.1096/fj.202602531R

J Sci Med Sport. 2026 Aug 16. pii: S1440-2440(26)00528-1. [Epub ahead of print]

Six weeks of isocaloric moderate- and heavy-intensity continuous training improves fitness but does not alter plasma cytokines in healthy young adults.

Seth F McCarthy, Garett S Jackson, Hashim Islam, Jonathan P Little.

OBJECTIVES: The anti-inflammatory effects of exercise training are hypothesized to involve changes in circulating cytokine concentrations, however the influence of exercise intensity is unclear. We determined the impact of exercise intensity, prescribed relative to lactate threshold (LT), on changes in fitness and plasma cytokines in a 6-week randomized controlled trial.
DESIGN: RCT.
METHODS: Healthy, young adults (N = 56, 27 males/29 females, age: 22 ± 3 y, peak oxygen consumption [VO2peak]: 38.4 ± 9.5 mL∙kg-1∙min-1) were randomized (2:2:1) to 6 weeks of thrice weekly isocaloric continuous cycling in the moderate (MICT; n = 21) or heavy (HICT; n = 24) intensity domain, or no-exercise control (CTRL; n = 11). Fasting plasma interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and fitness were assessed at baseline and post-training.
RESULTS: There was no impact of training or intensity (all p > 0.05) on changes in IL-6 (MICT +0.03 pg∙mL-1 95% CI -0.08, 0.13; HICT +0.03 pg∙mL-1 95% CI -0.08, 0.13; CTRL -0.14 pg∙mL-1 95% CI -0.30, 0.01), IL-10 (MICT +0.05 pg∙mL-1 95% CI -0.01, 0.11; HICT +0.02 pg∙mL-1 95% CI -0.05, 0.08; CTRL -0.02 pg∙mL-1 95% CI -0.11, 0.08), or TNF-α (MICT +0.12 pg∙mL-1 95% CI -0.01, 0.26; HICT +0.07 pg∙mL-1 95% CI -0.06, 0.21; CTRL -0.03 pg∙mL-1 95% CI -0.22, 0.17). VO2peak (absolute and relative) and power at LT increased with training (p < 0.002) with no significant differences between MICT and HICT (p > 0.331).
CONCLUSIONS: In conclusion, 6 weeks of isocaloric, LT-prescribed training in the moderate and heavy domains improves fitness but does not appear to impact fasting plasma cytokine concentrations in healthy young adults.

Keywords: Exercise training; Interleukin-10; Interleukin-6; Lactate threshold; Peak oxygen consumption; Tumor necrosis factor alpha

DOI: https://doi.org/10.1016/j.jsams.2026.08.207