Whey protein plus exercise and muscle protein synthesis
What it found
In healthy adults, whey protein taken with exercise increased muscle protein synthesis measured 3 to 5 hours later.
The authors say the effect depended on timing and dose.
What they found
Studies in people
Muscle protein synthesis
Whey protein plus exercise raised the muscle protein synthesis rate 3 to 5 hours after exercise compared with exercise alone. The increase ranged from 1.3 to 1.6 times when taken right after exercise.
Timing before exercise
Taking whey protein 45 minutes before multiple sets of leg exercise raised the synthesis rate 2.5 times compared with a placebo. Taking it 30 minutes before other exercise raised it 1.1 to 1.3 times.
Dose response
Larger doses of whey protein led to larger increases in the muscle protein synthesis rate, across doses from 10 g to 60 g. In one study, 40 g after exercise gave a 1.2 times higher rate than 20 g.
Signalling proteins early
Whey protein plus exercise increased the activity of several proteins in the AKT/mTOR pathway 1 to 2 hours after exercise. These included AKT, mTOR, 4E-BP1, p70S6K and rpS6.
Signalling proteins later
By 4 to 5 hours after exercise, the activity of p70S6K and rpS6 had fallen below the level seen with exercise alone. AKT and mTOR activity had returned to the level seen with exercise alone.
Whey versus other proteins
Whey protein led to similar muscle protein synthesis as soy protein in one study. In another, whey raised the synthesis rate 2.3 times from baseline while milk raised it 0.9 times. A blend of whey, soy and casein worked better than whey alone.
What the authors conclude
“The combination of whey protein supplementation and exercise improves MPS in a time- and dose-dependent manner.”
Also in their conclusions
- They conclude that whey protein supplementation combined with exercise improves muscle protein synthesis in a time- and dose-dependent manner.
- They advise that consuming 20-40g of whey protein before multiple sets of resistance exercise may enhance myofibrillar FSR and activate the AKT/mTOR pathway, thereby augmenting MPS and extending the anabolic window.
How it was done
The best timing and dose of whey protein for boosting muscle protein synthesis after exercise were still debated. The authors wanted to clarify the time pattern and find the best supplementation strategy.
They pooled 21 randomised controlled trials in healthy adults, 15 in the main analysis and 6 described separately. The trials used whey protein doses from 10 g to 60 g per session, with muscle samples taken to measure protein synthesis and related signalling proteins.
What it can’t tell you
- The studies were short and used single bouts of exercise, so they cannot show what happens with long-term training.
- Most participants were male, so the results may not apply to women.
- The studies used muscle biopsies, which measure protein synthesis directly, but they do not show whether this leads to more muscle growth or strength over time.
Who paid
- Funding
- Funded by National Natural Science Foundation of China; Shanghai Key Lab of Human Performance (Shanghai University of Sport) (from the PubMed record).
- Conflicts
- The authors declare no conflicts of interest.
- Authors work at
- Shanghai University of Sport, China; Fudan University, China; Naval Medical University, China
The paper
- Title
- Whey Protein Supplementation Combined with Exercise on Muscle Protein Synthesis and the AKT/mTOR Pathway in Healthy Adults: A Systematic Review and Meta-Analysis
- Type
- Systematic review and meta-analysisThe authors follow a set, published method to find every relevant study, then combine the numbers from them into one result.
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Ji X, Ye X, Ji S, et al (2025). Whey Protein Supplementation Combined with Exercise on Muscle Protein Synthesis and the AKT/mTOR Pathway in Healthy Adults: A Systematic Review and Meta-Analysis. Nutrients. doi:10.3390/nu17162579Free full textPubMed 40871607DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error