Daily Myofibrillar Protein Synthesis Rates in Response to Low- and High-Frequency Resistance Exercise Training in Healthy, Young Men.

Abstract

The impact of resistance exercise frequency on muscle protein synthesis rates remains unknown. The aim of this study was to compare daily myofibrillar protein synthesis rates over a 7-day period of low-frequency (LF) versus high-frequency (HF) resistance exercise training. Nine young men (21 ± 2years) completed a 7-day period of habitual physical activity (BASAL). This was followed by a 7-day exercise period of volume-matched, LF (10 × 10 repetitions at 70% one-repetition maximum, once per week) or HF (2 × 10 repetitions at ∼70% one-repetition maximum, five times per week) resistance exercise training. The participants had one leg randomly allocated to LF and the other to HF. Skeletal muscle biopsies and daily saliva samples were collected to determine myofibrillar protein synthesis rates using 2H2O, with intracellular signaling determined using Western blotting. The myofibrillar protein synthesis rates did not differ between the LF (1.46 ± 0.26%/day) and HF (1.48 ± 0.33%/day) conditions over the 7-day exercise training period (p > .05). There were no significant differences between the LF and HF conditions over the first 2 days (1.45 ± 0.41%/day vs. 1.25 ± 0.46%/day) or last 5 days (1.47 ± 0.30%/day vs. 1.50 ± 0.41%/day) of the exercise training period (p > .05). Daily myofibrillar protein synthesis rates were not different from BASAL at any time point during LF or HF (p > .05). The phosphorylation status and total protein content of selected proteins implicated in skeletal muscle ribosomal biogenesis were not different between conditions (p > .05). Under the conditions of the present study, resistance exercise training frequency did not modulate daily myofibrillar protein synthesis rates in young men.