Does Exercise Intensity Influence Dietary Protein Requirements Of Male Endurance Athletes?
Bibliographic record
Abstract
Adequate protein intake is important for endurance athletes to replenish exercise-induced amino acid (AA) oxidation and support post-exercise muscle and whole body protein synthesis. High-intensity endurance exercise is associated with increased carbohydrate oxidation during exercise and greater protein turnover (synthesis and breakdown) after exercise relative to lower intensity exercise. Muscle glycogen depletion can increase AA oxidation during exercise and increase daily protein requirements. PURPOSE: To determine the impact of exercise intensity during prolonged endurance exercise on estimates of dietary protein requirements in endurance athletes. METHODS: Eight males (26±3y, 76±16kg; 62±6 ml O2·kg-1· min-1; mean±SD) completed two trials in a randomized order with exercise (20-km run) performed at a low (LOW; 72±1% HRmax, 55±5% VO2peak) or high (HIGH; 88±1%HRmax, 75±7% VO2peak) intensity. After 2 days of exercise and dietary (1.4g·kg-1·d-1 protein) control, participants consumed 0.6g·kg-1 CHO before a 20-km treadmill run with continuous HR monitoring and periodic measurement of gas exchange (indirect calorimetry). During the 8h post-exercise recovery period, participants consumed 8.6g·kg-1·d-1 CHO and hourly meals providing 0.93g ·kg-1·d-1 protein as crystalline AA modeled after egg protein, which was enriched with [13C]phenylalanine as an indicator AA. Breath and urine were collected at isotopic and metabolic steady state to determine phenylalanine excretion (F13CO2), flux (Q; estimate of protein breakdown), and oxidation (OX; reciprocal of protein synthesis). RESULTS: Preliminary analysis (n=6) showed that respiratory exchange ratio during exercise was higher in HIGH vs. LOW (0.92±0.03 vs. 0.88±0.03, p<0.05), which corresponded to a 37% greater CHO oxidation rate in HIGH (3.12±0.76 vs. 1.96±0.52 g·min-1, p<0.01). Exercise duration was shorter in HIGH vs LOW (86±18 vs. 112±23 min, p<0.01). F13CO2 was not different between trials (HIGH: 0.94±0.25 vs. LOW: 0.89±0.14 umol·kg-1·h-1, p>0.05). Urinary analysis is ongoing to determine Q and OX. CONCLUSION: Preliminary findings suggest that prolonged, high-intensity endurance exercise increases CHO oxidation during exercise but has little impact on estimates of protein requirements of male endurance athletes.
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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 | 0.001 | 0.001 |
| 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 | 0.000 |
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".