Influence of age and pubertal status on substrate utilization during exercise with and without carbohydrate intake in healthy boys
Bibliographic record
Abstract
Substrate utilization during exercise is known to differ between children and adults, but whether these differences are related to pubertal status is unclear. The objective of this study was to investigate the effects of pubertal status on endogenous (CHOendo) and orally ingested exogenous (CHOexo) carbohydrate and fat oxidation rates during exercise. Twenty boys at the same chronological age (12 y) were divided into three pubertal groups (pre-pubertal, PP: n=7; early-pubertal, EP: n=7; mid- to late-pubertal, M-LP: n=6) and consumed either a placebo or 13C-enriched 6% CHO drink while cycling for 60 min at approximately 70% of their maximal aerobic power (VO2 max). Another group of 14-year-old boys (pubertal, n=9) completed all procedures. Substrate utilization was calculated for the final 15 min of exercise using indirect calorimetry and stable isotope methodology. CHOexo decreased fat (p<0.001) and increased total CHO (p<0.001) oxidation, irrespective of group. Fat oxidation was higher (p=0.01) in younger boys than in older boys, but similar (p>or=0.33) among PP, EP, and M-LP boys. CHOexo contributed to approximately 30% of energy expenditure (EE) in PP and EP, but to only 24% in M-LP (p=0.02), which was identical to the older boys (24%). CHOexo oxidation rate as a percentage of EE was inversely related to testosterone levels (r=-0.51, p=0.005, n=29). It was concluded that reliance on CHOexo during exercise is particularly sensitive to pubertal status, with the highest oxidation rates observed in pre- and early-pubertal boys, independent of chronological age.
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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 | 0.001 |
| 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) | 0.001 | 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".