Whey Protein Before and During Resistance Exercise Has No Effect on Muscle Mass and Strength in Untrained Young Adults

Purpose: To determine the effects of whey protein before and during resistance exercise (RE) on body composition and strength in young adults. Methods: Participants were randomized to ingest whey protein (PRO; 0.3 g/kg protein; n = 9, 24.58 +/- 1.8 yr. 88.3 +/- 17.1 kg, 172.5 +/- 8.0 cm) or placebo (PLA; 0.2 g/kg cornstarch maltodextrin +0.1 g/kg sucrose; n = 8, 23.6 +/- 4.4 yr, 82.6 +/- 16.1 kg, 169.4 +/- 9.2 cm) during RE (3 sets of 6-10 repetitions for 9 whole-body exercises), which was performed 4 d/wk for 8 wk. PRO and PLA were mixed with water (600 nil); 50% of the solution containing 0.15 g/kg of PRO or PLA was consumed immediately before the start of exercise, and similar to 1.9% of the remaining solution containing similar to 0.006 g/kg of PRO or PLA was consumed immediately after each training set. Before and after the study, measures were taken for lean-tissue mass (dual-energy X-ray absorptiometry), muscle size of the elbow and knee flexors and extensors and ankle dorsiflexors and plantar flexors (ultrasound), and muscle strength (1-repetition-maximum chest press). Results: There was a significant increase (p < .05) in muscle size of the knee extensors (PRO 0.6 +/- 0.4 cm, PLA 0.1 +/- 0.5 cm), knee flexors (PRO 0.4 +/- 0.6 cm, PLA 0.5 +/- 0.7 cm) and ankle plantar flexors (PRO 0.6 +/- 0.7 cm, PLA 0.8 +/- 1.4 cm) and chest-press strength (PRO 16.6 +/- 11.1 kg, PLA 9.1 +/- 14.6 kg) over time, with no differences between groups. Conclusion: The ingestion of whey protein immediately before the start of exercise and again after each training set has no effect on muscle mass and strength in untrained young adults.