Amino acid supplementation accelerates resolution of exercise-induced phagocyte infiltration in human skeletal muscle
Year: 2025
Type: article
Study designs: Randomized Controlled Trial, Clinical Trial
Abstract: Background Amino acids activate neutrophil phagocytosis and free radical release in vitro.Aim We examined the effects of amino acid supplementation on post-exercise accumulation of myeloperoxidase-positive (MPO⁺) cells in human skeletal muscle using a randomized, double-blind, placebo-controlled crossover design.Methods Ten young men (22 ± 2.8 years) consumed either amino acids (15 g) or an isocaloric placebo before resistance exercise. Biopsies of the vastus lateralis muscle were collected at baseline, immediately after exercise (0 h), and 24 h post-exercise.Results Resistance exercise increased MPO⁺ cell infiltration (+161%, p = 0.02) and 8-hydroxy−2-deoxyguanosine (8-OHdG) levels (+66%, p = 0.02) at 24 h. Amino acid supplementation accelerated MPO⁺ cell infiltration to 0 h (+100%, p = 0.03), which diminished by 24 h post-exercise (+53%, p = 0.06). Immunofluorescence co-staining revealed that MPO⁺ cells exhibited markedly higher mitochondrial density (TOM20-labeled) and integrated with the injured regions of adjacent myofibers showing lower mitochondria. Other infiltrating MPO-negative cells also contributed mitochondria to exercised muscle tissue, resulting in an overall ~2-fold increase in mitochondrial content during 24-h recovery (p < 0.001), similar under both supplementation conditions. Cellular senescence marker p16Ink4a mRNA decreased by 58% at 24 h post-exercise, with an earlier reduction observed under amino acid treatment (0 h: –49%, p = 0.05).Conclusion These findings indicate that amino acid supplementation accelerates the resolution of inflammation in exercised human skeletal muscle. Immunofluorescence evidence further suggests that infiltrating bone marrow-derived cells contribute to fast mitochondrial gains as part of the muscle damage-response following exercise.
Institutions: Zhejiang Normal University, University of Taipei, University of Parma, China Medical University, Asia University, China Medical University, Tzu Chi Foundation, Asia University, China Medical University Hospital, Buddhist Tzu Chi Medical Foundation, Universitas Muhammadiyah Semarang, Soochow University, National Yang Ming Chiao Tung University, Taipei Veterans General Hospital, Education University of Hong Kong
Language: English
Subfield: Rehabilitation
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,490
OpenAlex ID: W4416833913