Individual Variability in mRNA Expression Responses to Resistance Exercise

Abstract

Several studies have observed variability in the individual mRNA expression responses to acute exercise. However, because observed responses contain a degree of measurement error and within-subject variability, it is unknown whether variability in the mRNA expression responses to acute exercise exists. The purpose of this thesis was to determine whether variability in the individual mRNA expression responses to acute exercise exists. Utilizing freely available microarray data, variability in observed responses to acute resistance exercise (RE) and CON were compared to determine the variability in mRNA expression responses to RE. The previously published microarray study (1) collected skeletal muscle biopsies before (PRE) and 24 hours after (POST) RE/CON and genome-wide mRNA expression responses were measured using Affymetrix microarray chips. Standard deviation (SD) in the observed responses to CON were subtracted from RE to determine an effect size of variability in the responses (ESIR) to RE. Although 15849 transcripts had an incalculable ESIR (i.e. SD in observed responses to CON > RE), 29933 transcripts had an ESIR > 0 and 1486 mRNA had a large ESIR (i.e. ESIR > 0.6). WebGestalt’s gene set enrichment analysis revealed that the 1486 mRNA with a large ESIR were involved in several pathways proposed to play roles in regulating the adaptive responses to resistance training (RT). The 1486 mRNA with a large ESIR were also compared to a group of 2756 mRNA (2) previously found to have acute expression responses that correlate with skeletal muscle strength and size adaptations following RT. 109 mRNA with large ESIR were also among the mRNA previously found to correlate with both skeletal muscle strength and size adaptations to RT. Together, these results suggest that individual variability in the mRNA expression responses to RE exist, and highlight 109 mRNA that potentially play key roles in predicting skeletal muscle adaptations to RT.