Acute And Chronic Resistance Exercise Differentially Modulates The Skeletal Muscle Metabolome

Abstract

Acute resistance exercise (RE) is associated with acutely increased protein synthesis while repeated resistance training (RT) increases muscle growth. Although the molecular events that initiate these events are well described there is a lack of knowledge concerning the involvement of skeletal muscle metabolic pathways in the adaptive response towards RE. Yet, skeletal muscle metabolomic studies have not analysed differences in the metabolomic signature between acute RE and repeated loading of skeletal muscle by RT. PURPOSE: To determine myofiber diameter and the skeletal muscle metabolome after acute and prolonged RE in humans . METHODS: 7 male subjects (Age: 24±4 years; Height: 180±8 cm; Weight: 81±10 kg) conducted 13 RE sessions over 5 weeks. Muscle biopsies from vastus lateralis muscle were taken at rest (Rest), 45 min after the first and the last (13th) RE session. Muscle samples were analysed for changes in myofiber diameter via immunohistochemistry and metabolites by conducting untargeted metabolomics analysis on an LC-MS platform. RESULTS: 645 metabolites were detected after RE and RT comprising different clusters of skeletal muscle metabolites. From these, 508 metabolites could be assigned to amino acids, nucleotides, lipids, carbohydrates, energy metabolism, vitamins and co-factors as well as anti oxidants. Five weeks of RT significantly increased the size of slow type I and fast/intermediate type II muscle fibres by 9+-4% and 10+-3 % respectively. Fatty acid metabolites decreased significantly (p<0.05) after RT. After RE, metabolites associated with amino acid metabolism significantly increased (p<0.05). Specifically 3-methylhistidine increased acutely after RE likely associated with increased degradation of myofibrillar proteins after unaccustomed RE. Antioxidant metabolites were decreased (p<0.05) while Metabolites derived from purine nucleotid cycle were partly increased or decreased (p<0.05) after RE. CONCLUSIONS: Acute unaccustomed RE and prolonged RT, associated with hypertrophy induce significant but different changes of the skeletal muscle metabolome likely reflecting the functional and structural adaptation of the skeletal muscle environment. Suported by Grant from Federal Institute of Sports Science: ZMVI4-2516BI0106