Acute And Chronic Effects Of Branched-chain Amino Acid Supplementation: A Systematic Review And Meta-analysis
Bibliographic record
Abstract
Branched-chain amino acids (BCAA) influence muscle protein turnover through the mTOR signaling pathway and phosphorylation of translation initiation factors. It has been suggested that BCAA supplementation may decrease muscle damage, attenuate soreness, promote recovery, and improve strength and hypertrophic adaptations to resistance exercise; however, the findings are inconsistent and thus the question of efficacy of BCAA supplementation is uncertain. PURPOSE: We performed a systematic review and meta-analysis to determine the influence of acute BCAA supplementation on perceived soreness and performance recovery following a bout of resistance exercise. Additionally, we analyzed the effect of 6+ weeks of resistance training with BCAA on fat free mass and strength. METHODS: A systematic search was conducted in Medline, Embase, CINAHL and SportDiscus. Fifteen studies with 348 participants were eligible for inclusion. Random-effects meta-analyses were performed in RevMan (Review Manager (RevMan), V.5.3. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014). Acute outcomes included isometric knee extension, vertical jump, and perceived muscular soreness. Chronic outcomes included changes in fat free mass, upper- and lower-body strength. RESULTS: Acutely, BCAA supplementation following an acute bout of resistance exercise did not attenuate perceived soreness (SMD: -0.42, CI: (-0.95, 0.12), p=0.13) or attenuate performance decrements in the vertical jump (MD: 0.54, CI: (-1.05, 2.12), p=0.51) or reductions in isometric knee extension torque (SMD: 0.11, CI: (-0.39, 0.61), p=0.66). Chronic BCAA supplementation during resistance training did not influence resistance exercise induced changes in fat free mass (MD: 0.01, CI: (-0.70, 0.73), p=0.97), upper body strength (SMD: 0.08, CI (-0.63, 0.79), p=0.83) or lower body strength (SMD: 0.10, CI: (-1.15, 1.34), p=0.88). CONCLUSIONS: BCAA supplementation does not effectively reduce soreness, attenuate subsequent performance decrements, or influence muscular adaptations to resistance training.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.019 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.017 | 0.027 |
| Bibliometrics | 0.005 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".