Longevity & AgingWhey Protein Before Heavy Resistance Training Doubles Muscle Protein Synthesis
A systematic review and meta-analysis of 21 randomized controlled trials found that combining whey protein supplementation with exercise significantly boosts myofibrillar fractional synthetic rate (FSR) — the key measure of muscle protein synthesis — compared to exercise alone. The effect is both time- and dose-dependent. Consuming 20–40 g of whey protein before multiple sets of resistance exercise produced the largest FSR gains (up to 2.5-fold), while post-exercise ingestion consistently yielded 1.3–1.6-fold increases. Mechanistically, whey protein enhanced phosphorylation of AKT, mTOR, p70S6K, 4E-BP1, and rpS6 at 1–2 hours post-exercise, with signaling activity declining by 4–5 hours, clarifying the practical window for supplementation.
