Protein Requirements Are Increased in Endurance-Trained Athletes but Similar between Females and Males during Postexercise Recovery
Bibliographic record
Abstract
PURPOSE: This study aimed to determine the daily protein requirements of female and male endurance athletes in a home-based setting using noninvasive stable isotope methodology (i.e., indicator amino acid oxidation). METHODS: Eight males (30 ± 3 yr; 78.6 ± 10.5 kg; 75.6 ± 7.5 mL·kgFFM-1·min-1; mean ± SD) and seven females (30 ± 4 yr; 57.7 ± 5.0 kg; 77.5 ± 7.1 mL·kgFFM-1·min-1) during the midluteal phase were studied. After 2 d of controlled diet (1.4 gprotein·kg-1·d-1) and training (10 and 5 km run·d-1, respectively), participants completed a 20-km run before an at-home indicator amino acid oxidation trial testing a suboptimal, a moderate, and an excess (i.e., 0.2, 1.2, and 2.0 g·kg-1·d-1, respectively) protein intake. Protein was consumed as a crystalline amino acid mixture containing [1-13C]phenylalanine to examine whole-body phenylalanine flux and phenylalanine oxidation (PheOx; the reciprocal of whole-body protein synthesis) through breath and urine sample collection. A modified biphasic linear regression determined the breakpoint in PheOx for each participant to generate an estimated average intake that would maximize whole-body protein synthesis for each sex. RESULTS: PheOx was different (P < 0.01) between all protein intakes with no effect of sex (P = 0.63). Using a modified three-point curve resulted in a breakpoint that was not different (P = 0.94) between males and females (1.60 and 1.61 g·kg-1·d-1, respectively). The recommended intake (i.e., upper 95% confidence interval) was estimated to be 1.81 and 1.89 g·kg-1·d-1 for males and females, respectively. CONCLUSIONS: Our findings indicate that endurance athletes consuming a daily protein intake toward the upper end of current consensus recommendations (~1.85 g·kg-1·d-1) will maximize whole-body protein synthesis during postexercise recovery regardless of sex.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".