GENETIC AND MORPHOLOGICAL DETERMINANTS OF ATHLETIC PERFORMANCE: INSIGHTS INTO EXERCISE ADAPTATION, MUSCULAR FUNCTION, AND PHYSICAL FITNESS

Abstract

The actions of skeletal-muscle molecular regulation, morphology, and the function of skeletal muscle, and training-specific physiological adaptation, all interact to affect athletic performance. Combining these domains may provide some explanation for the differences in performance between resistance and endurance training and concurrent exercise training. This study compared physiological and skeletal-muscle transcriptomic adaptations across training modes and explored associations between exercise-responsive genes and individual changes in physical performance. Paired pre- and post-training data were analyzed from 18 healthy young men who completed 12 weeks of resistance, endurance, or concurrent training. Nine morphological and performance outcomes were assessed using nonparametric tests with multiplicity correction. RNA-sequencing counts from 36 skeletal-muscle samples were analyzed using paired DESeq2 models, followed by functional enrichment and gene–phenotype correlation analyses. Maximal aerobic power increased after concurrent and endurance training but decreased after resistance training, representing the only physiological outcome with a significant Holm adjusted between-group difference (adjusted p = 0.030). Concurrent training produced 351 differentially expressed genes, compared with 50 after endurance training and 16 after resistance training. Concurrent and endurance responses were dominated by collagen and extracellular-matrix remodeling, whereas resistance training enriched muscle-contraction, myofibril-assembly, complement, and fatty-acid metabolic processes. Five of 234 gene–phenotype correlations were nominally significant, but none survived false-discovery-rate correction. Training mode played a key role in exercise adaptation, with functional and transcriptional differences. A comprehensive, integrated molecular and physiological evaluation can help explain the process of athletic adaptation, but cannot determine the effects of a single gene.