The Effect Of Two Different Creatine Formulations On Skeletal Muscle Creatine Retention
Bibliographic record
Abstract
Many creatine (CR) supplements contain dextrose, since early research suggested that a large insulin spike enhanced CR uptake into muscle. However, it has also been reported that CR uptake is primarily dependent upon sodium vs. insulin, which has led to the formulation of products that contain higher amounts of sodium and no dextrose; therefore, these products may also be Calorie free. Few studies have compared the efficacy of these 'sugar free' CR products to more traditional formulations that include dextrose. PURPOSE: To compare the effects of two different CR formulations on total skeletal muscle CR retention (TCR) following loading and maintenance doses. METHODS: 19 resistance trained men (X age ± SEM = 29±2 yr) randomly received one of two treatment conditions: (1) dextrose-free CR supplement containing 5g CR citrate and 250mg sodium (n = 9; SOD) or (2) a CR supplement containing 5g CR monohydrate and 36g dextrose (n = 10; DEX). Each treatment was dissolved in 16oz water and ingested 4 times per day for 5d (loading) followed by 5 g/d for 28d (maintenance). Body weight (BW) was measured using a calibrated physician's scale and muscle biopsies were obtained from the vastus lateralis using a fine needle aspiration technique at baseline (BL) and following the loading and maintenance doses for the determination of free CR (fCR) and phosphocreatine (PCR). The data were analyzed using 2x3 ANOVA (p<.05). RESULTS: All CR values are expressed as mmol/kg dw. There were no significant time x group interactions for BW, fCR, PCR, or TCR; however, there was a significant time effect for fCR (p =.003). Scheffe' post hoc tests showed a significant increase in fCR at 5d (59.63 ± 5.8) and 28d (58.40 ± 5.23) when compared to BL (47.90 ± 5.23). CONCLUSION: These findings suggest that SOD and DEX CR formulations are equally effective for increasing fCR in resistance trained men. The increase in fCR (25%) following 5d of loading is comparable to increases reported in previous studies, and remained elevated throughout the 28d maintenance period. Although 5d CR loading with DEX resulted in an extra 576 kcal/d, there were no significant differences between or within groups for BW. The mean increase in BW at 5d and 28d for all 19 subjects compared to BL was 1.34 kg and 2.11 kg, respectively. Supported by a CU Research Initiative Grant and 8-Ball Nutrition, Omaha, NE
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 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".