Effects of short-term betaine supplementation on muscle endurance and indices of endocrine function following acute high-intensity resistance exercise in young athletes
Bibliographic record
Abstract
Objective This study examined the effects of short-term betaine supplementation on muscle endurance, plasma lactate, testosterone and cortisol levels, and the testosterone to cortisol (T/C) ratio in response to acute resistance exercise (RE).Method Using a double-blind, crossover study design, 10 handball players (age ± SD = 16 ± 1 yrs) without prior-structured RE experience performed a high-intensity RE session (leg press followed by bench press; 5 sets to volitional fatigue using 80% baseline 1 repetition maximum (1RM)), before and after 14 days of either placebo (maltodextrin) or betaine (2.5 g·d−1) supplementation. A 30-day washout period separated each treatment. 48 h prior to testing sessions, participants recorded their food intake and did not perform strenuous exercise. Venous blood was sampled before supplementation, and before and after each RE session.Results After betaine supplementation, participants performed more repetitions (p < 0.001) during the leg press (Betaine: 35.8 ± 4.3; Placebo: 24.8 ± 3.6, Cohen’s d = 2.77) and bench press (Betaine: 36.3 ± 2.6; Placebo: 26.1 ± 3.5, Cohen’s d = 3.34). Betaine resulted in lower post-exercise cortisol (Betaine: 7.6 ± 1.7; Placebo: 13 ± 3.4 µg.dL−1, p = 0.003, generalized eta squared (ηG2) = 0.49) and lactate (Betaine: 5.2 ± 0.3; Placebo: 6 ± 0.3 mmol.L−1, p < 0.001, ηG2 = 0.96) and higher total testosterone (Betaine: 15.2 ± 2.2; Placebo: 8.7 ± 1.7 ng.mL−1, p < 0.001, ηG2 = 0.87) and T/C ratio (Betaine: 0.21 ± 0.05; Placebo: 0.07 ± 0.02, p < 0.001, = 0.82).Conclusions Two weeks of betaine supplementation improved upper- and lower-body muscle endurance and influenced indices of endocrine function following an acute session of high-intensity RE in adolescent handball players.
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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) | 0.001 | 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 | 0.001 | 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".