Protein during endurance training improved time to exhaustion in a review
Pooled trials reported an endurance-test benefit, while lean mass and several measures of body composition and exercise capacity showed no significant overall improvement.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
Protein supplementation during endurance training improved time to exhaustion in the pooled analysis. Lean mass showed a small, statistically nonsignificant increase. Pooled results for maximal oxygen uptake, body weight, body fat, and aerobic or anaerobic capacity showed no significant benefits. The performance finding should therefore not be extended to broad improvements in fitness or body composition.
This abstract-based account lacks supplementation protocols, comparator details, and intervention durations. It also gives limited uncertainty information for the untrained subgroup, restricting interpretation of whether training experience meaningfully changes the response.
What researchers found
Time to exhaustion during endurance exercise
Longer time to exhaustion with protein supplementation, expressed in standard-deviation units rather than minutes or percentages. Comparator conditions and assessment timeframes were not reported.
Performance has several meanings
Time to exhaustion measures how long participants continued an endurance test. It is distinct from maximal oxygen uptake and body composition, so improvement in this endpoint does not imply that all training adaptations improved.
Subgroup findings need restraint
The authors suggested that untrained participants might show greater maximal oxygen-uptake improvements. Because the pooled result was nonsignificant and subgroup detail was limited, this observation is best treated as a question for further research.
The original publication
Effects of protein supplementation on body composition, physiological adaptations, and performance during endurance training: a systematic review and meta-analysis.
Xiao Y, Deng Z, Sun W et al.
Front Nutr · 2025
- PubMed ID
- 40851900
- Record checked
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