The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 27511985 · doi:10.14814/phy2.12893
What was done
Thirty resistance-trained young men were divided into two groups based on lean body mass (LBM): lower LBM (≤65 kg, n = 15) and higher LBM (≥70 kg, n = 15). Each participant completed two trials in random crossover order, ingesting either 20 g or 40 g of whey protein following a single bout of whole-body resistance exercise. Myofibrillar protein synthesis (MPS) was measured during recovery using a 13C6-phenylalanine tracer infusion and muscle biopsies.
What was found
MPS responses did not differ between the lower and higher LBM groups at either dose (20 g: 0.048 ± 0.018%·h⁻¹ in LLBM vs 0.051 ± 0.014%·h⁻¹ in HLBM; 40 g: 0.059 ± 0.021%·h⁻¹ in LLBM vs 0.059 ± 0.012%·h⁻¹ in HLBM). When groups were combined, MPS was significantly higher following 40 g of whey protein compared to 20 g (0.059 ± 0.020%·h⁻¹ vs 0.049 ± 0.020%·h⁻¹; P = 0.005).
Why it matters
This study challenges the conventional view that 20–25 g of protein maximally stimulates post-exercise muscle protein synthesis, demonstrating that a larger 40 g dose provides additional anabolic stimulus following whole-body resistance exercise regardless of an individual's lean body mass.
Limits
The study included only young, resistance-trained men, limiting generalizability to females, older adults, or untrained individuals. It evaluated acute MPS over a single post-exercise recovery window rather than long-term muscle hypertrophy, and tested only two discrete protein doses.
Cited by
- context A single meal containing 20 grams of high-quality protein maximizes muscle protein synthesis for up to 4 to 6 hours.