Effects of protein supplementation during resistance-training in young adults
Although the signalling pathways for stimulating muscle protein synthesis are increased after resistance-training (RT), this response is delayed in the post-absorptive period. Emerging evidence suggests that protein supplementation immediately before and after RT is important for creating an anabolic environment for muscle growth. However, the effects of protein supplementation during RT are unknown. Purpose: To investigate the effects of protein supplementation during RT on body composition, muscle strength and endurance, muscle protein catabolism, and kidney function. Methods: Using a double-blind, repeated measures design, healthy adults (N=30, 18-30 yrs) will be randomly assigned to one of two groups: Protein (N=15; 0.3g/kg body mass of protein during RT) or Placebo (N=15; 0.3g/kg body mass of maltodextrin and sucrose during RT). Supplements will be mixed with water and 1/27th of the solution will be consumed following each set; 3x/week, 9 weeks; 3 sets of 10, 8 and 6 reps to muscle fatigue, 9 exercises). The primary dependent variables to be assessed prior to and following the study will include: body composition (muscle, bone, fat; dual energy x-ray absorptiometry), muscle thickness (ultrasound), strength (1-repetition maximum leg press and chest press), muscle endurance (total number of reps performed over 3 sets at 70% baseline 1-RM for leg press and chest press), muscle protein catabolism (urinary 3-methylhistidine) and kidney function (urinary microalbumin).