{'fraction_non_alphanumeric': 0.05425867507886435, 'fraction_numerical': 0.03533123028391167, 'mean_word_length': 5.244094488188976, 'pattern_counts': {'":': 0, '<': 2, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Influence of Myosin Heavy Chain Protein Isoforms on Akt/mTOR Signaling and mRNA Expression Following Resistance Exercise in Trained Men

The purpose of this study was to investigate anabolic signaling responses in resistance‐trained men, and to examine the influence of myosin heavy chain (MHC) isoform composition on the magnitude of anabolic signaling. Eight resistance‐trained men (24.9±4.3y; 91.2±12.4kg; 176.7±8.0cm) performed a whole body, high‐volume resistance exercise protocol (REX) and a control protocol (CTL) in a balanced, randomized order. Participants were provided standardized meals during each protocol. Muscle biopsies were completed at baseline (BL), 2‐ (2H) and 6‐hours post‐exercise (6H). BL biopsies were analyzed for MHC isoform composition. Phosphorylation of proteins specific to the Akt/mTOR signaling pathway and MHC mRNA expression were quantified. Phosphorylation of p70S6k was significantly greater in REX compared to CTL at 2H (p=0.04). MHC mRNA expression and other targets in the Akt/mTOR pathway were not significantly influenced by REX. The percentage of type IIX isoform was inversely correlated (p<0.05) with type I and type IIA MHC mRNA expression (r=‐0.69‐ ‐0.93). Maximal strength was also observed to be inversely correlated (p<0.05) with Type I and Type IIA MHC mRNA expression (r=‐0.75– ‐0.77) and p70S6k phosphorylation (r=‐0.75). Results indicate that activation of p70S6k occurs within 2‐h following REX in resistance‐trained men. Results also suggest that highly trained, stronger individuals have an attenuated acute anabolic response.