Daily protein-polyphenol ingestion increases daily myofibrillar protein synthesis rates and promotes early muscle functional gains during resistance training

Abstract

Factors underpinning the time-course of resistance-type exercise training (RET) adaptations are not fully understood. The present study hypothesized that consuming a twice-daily protein-polyphenol beverage (PPB; n=15; age, 24 ± 1 years; BMI, 22.3 ± 0.7 kg·m-2) previously shown to accelerate recovery from muscle damage and increase daily myofibrillar protein synthesis (MyoPS) rates would accelerate early (10 sessions) improvements in muscle function and potentiate quadriceps volume and muscle fiber cross-sectional area (fCSA) following 30 unilateral RET sessions in healthy, recreationally active, adults. Versus isocaloric placebo (PLA; n=14; age, 25 ± 2 years; BMI, 23.9 ± 1.0 kg·m-2), PPB increased 48 h MyoPS rates after the first RET session measured using deuterated water (2.01 ± 0.15 %·d-1 vs. 1.51 ± 0.16 , respectively; P<0.05). Additionally, PPB increased isokinetic muscle function over 10 sessions of training relative to the untrained control leg (%U) from 99.9 ± 1.8 pre-training to 107.2 ± 2.4 %U at session 10 (versus 102.6 ± 3.9 to 100.8 ± 2.4 %U at session 10 in PLA; interaction P<0.05). Pre-to-post-training, PPB increased type II fCSA (PLA: 120.8 ± 8.2 to 109.5 ± 8.6 %U; PPB: 92.8 ± 6.2 to 108.4 ± 9.7 %U; interaction P<0.05), but the gain in quadriceps muscle volume was similar between groups. Similarly, PPB did not further increase peak isometric torque, muscle function or MyoPS measured post-training. This suggests that although PPB increases MyoPS and early adaptation, it may not influence longer term adaptations to unilateral RET.