Effect of Exercise Training Modality on Skeletal Muscle mRNA Abundance in Young and Older Adults

Abstract

PURPOSE: The specific effects of different exercise modalities on mitochondrial (mito) and myofibrillar (myo) protein gene expression are not fully understood. We determined the effects of endurance (ET), resistance (RT), and combined (CT) training on skeletal muscle mRNA abundance of mito and myo proteins in young and older adults. METHODS: 33 young (25+1y) and 27 older (70+2y) adults were randomized to one of three 8-wk training interventions: (i) Control: subjects maintained existing physical activity levels, (ii) ET: subjects cycled for 60 min at 65% of VO2 peak, 5×/wk. (iii), RT: subjects RT 4×/wk. Control subjects completed an additional 8-week (iv) CT training program following the completion of the control period. Subjects were assessed for VO2 peak, leg press 1RM, and had muscle biopsies before and 48 h after the last training session. Real-time PCR determined mRNA abundance of mito and myo proteins. ANOVA models were used to detect mean differences. RESULTS: At baseline, there were no significant differences between treatment groups for mRNA abundance. Also, the older subjects had lower VO2 peak (28+1 ml/kg/min vs. 18+1 ml/kg/min, p<0.05) and leg-press 1RM (130+8 kg vs. 80+6 kg, p<0.05). Table 1 presents the pre-posttraining % change values. CONCLUSIONS: ET increased VO2 peak and mRNA abundance of mito proteins in both young and older adults. RT increased skeletal muscle strength in both young and older adults. Although RT did not alter mRNA abundance of mito proteins in the young, these gene transcripts did increase in response to RT among the old. CT increased both VO2 peak and skeletal muscle strength, while also increasing mRNA abundance of mito and myo proteins in both young and older adults. Grants: R01AG09531, KL2RR084151Table 1: Percent change in fitness and mRNA abundance for mitochondrial and contractile proteins.