Author(s): STEAD, C., THOMAS, A.C.Q., D’SOUZA, A.C., MCKENDRY, J., LIM, C., SIEKMANN, I., PHILLIPS, S.M., BURNISTON, J.G., Institution: LIVERPOOL JOHN MOORES UNIVERSITY, Country: UNITED KINGDOM, Abstract-ID: 1742

INTRODUCTION:
We investigated muscle adaptations to aerobic training (AT) versus resistance training (RT) during the early untrained-state versus longer-term trained-state using novel deuterium oxide labelling and proteomic techniques. Our study aims to generate new insight into training mode-specific muscle adaptations by measuring protein-specific changes in abundance and synthesis rates.
METHODS:
In a within-subject longitudinal design, 14 (8F/6M) healthy individuals (20± 2y, body mass: 70±21 Kg) completed 10-wks of thrice weekly unilateral resistance (RT: 3 sets × 10-12 reps 80% 1-repetition maximum (RM) leg press and leg extension) and unilateral aerobic (AT: 4 × 5 min one-legged cycling at 65% Wattmax) training. Biopsies were taken at the start and end of a 1-week free-living period prior to training (Baseline), the 1st-wk of training (Early), and the 10th-wk of training (Later). Participants consumed deuterium oxide across all 3 study periods. Muscle samples (n = 5 individuals, 1M/4F) were analysed by liquid chromatography tandem-mass spectrometry. Within-subject 2-way ANOVA investigated interactions between exercise mode (RT vs AT) and study period (Baseline x Early x Later) in protein-specific abundance and synthesis rates. Significant differences (p<0.05) were investigated using bioinformatic analyses (proteins reported as UniProt identifiers).
RESULTS:
RT increased (p<0.005) 1RM leg press 116% (+65±10kg) and 1RM leg extension 76% (+16±5kg), whereas AT increased (p=0.025) unilateral Wmax 17% (+21±17W). Proteomic analysis quantified 2883 abundance and 1465 synthesis rates. Mixed-protein FSR (%/d) increased (34% NS) during Early RT only and was 15% above Baseline during Later RT and AT. Early RT increased the turnover of 22 (primarily myofibrillar) proteins, whereas Early AT increased the turnover of glycolytic enzymes and the abundances of 10 proteins of the KEGG pathway ‘Oxidative phosphorylation’ (OXPHOS; FDR = 0.03). Later AT increased the abundance of proteins associated with ‘Cellular respiration’ (FDR = 1.2e-17), including 16 Complex I (CI) subunits. Both RT and AT significantly increased abundance of 48 mitochondrial proteins, including 5 CI accessory subunits and regulators of mitochondrial quality (OPA1, MAIP1, AFG32, CHC10, MIC26, and GHITM). Later AT specifically increased the turnover of regulators of mitochondrial proteostasis, including the HSP70 co-chaperone BAG3 and eIF5A. Later RT specifically increased the turnover of 21 proteins, including glycolytic enzymes and regulators of mitochondrial morphology and quality control, such as CHCHD2 which increased (p < 0.01) in turnover rate from 5.7±4.9 %/d at Baseline to 13.6±2.8 %/d in Later RT.
CONCLUSION:
AT and RT resulted in improvements in mitochondrial quality via training-mode specific changes in abundance and synthesis rates. Remodelling of CI was specific to AT, whereas RT increased in the abundance and turnover of proteins associated with mitochondrial quality independent of changes in OXPHOS catalytic subunits.