Effect of Low-Dose Creatine Monohydrate Supplementation on Muscle Protein Catabolism and Formaldehyde Production in Older Men
Bibliographic record
Abstract
Dietary supplementation with high doses of creatine monohydrate (i.e. 20-21g/d) has the beneficial effect of decreasing muscle protein catabolism (Parise et al., J.Appl. Physiol. 2001) but may have a cytotoxic effect by increasing formaldehyde production (Poortmans et al., Med. Sci. Sports Exerc. 2005). PURPOSE: To determine whether lower doses of creatine (∼8.4g/d) given less frequently (i.e. 3d/wk) would have the beneficial effect of decreasing muscle protein catabolism without increasing formaldehyde production in a group of older men. METHODS: Older men (65.4±4.7y) were randomized (double blind) to receive either 0.1 g/kg body mass/d creatine (n=13), 0.1 g/kg body mass/d creatine and 0.3 g/kg body mass/d protein (n=10), or placebo (n=12) for 10 weeks. Subjects ingested their supplements 3 days per week, with half of the supplement ingested before, and half ingested after performing a bout of whole-body resistance training. Twenty-four hour urine samples were collected before and after the 10 weeks of training and supplementation and analyzed by HPLC for 3-methyl histidine (a marker of muscle protein catabolism) and formaldehyde (a marker of cytotoxicity). RESULTS: Results for the two groups receiving creatine did not differ; therefore, they were combined for comparison to the placebo group. Creatine supplementation decreased muscle protein catabolism (urinary 3-methyl histidine) by 40±32% which was significant compared to an increase of 29±116% for the placebo group (p=0.012). Neither creatine nor placebo groups had significant changes in urinary formalydehyde production (creatine: 24±81%; placebo: 24±92%). CONCLUSIONS: A low-dose of creatine supplementation (∼8.4g/d, 3d/wk, 10 weeks) during resistance training in older men has the beneficial effect of decreasing protein catabolism without the cytotoxic effect of increased formaldehyde production.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".