Meta-Analysis of the Effect of Exercise-Induced Dehydration on Endurance Performance
Bibliographic record
Abstract
It is generally accepted that exercise-induced dehydration impairs endurance performance. The effect of dehydration on endurance performance has not been yet systematically quantified. PURPOSE: Use the meta-analytic approach to determine the magnitude and importance of the effect of dehydration on endurance performance. METHODS: Studies were located via database searches, cross-referencing, and e-mails sent to researchers. Inclusion criteria were: dehydration induced during exercise; fluid replacement given orally; data to calculate percent change in power output, effect size and dehydration level; hydration level in the less-dehydrated control group between + 0.5 to −1% body mass; dehydration level in the more-dehydrated experimental group >1% body mass and>0.5% more than control; equal quantity of carbohydrate administered in control and experimental groups; and performance assessed in compensable exerciseheat stress. A random-effect model was used to determine the standardized effect. RESULTS: Fourteen studies met the inclusion criteria, providing 27 estimates. Exercise duration, exercise intensity and ambient temperature were respectively 94 ± 34 min (mean ± SD, range 60-171 min), 70 ± 12% (51-85%), and 26 ± 6°C (20-35°C). The decreases in body mass in control and experimental groups were 0.6 ± 0.3% and 2.4 ± 0.9%, respectively. Overall, mean power output fell by 2.0% (95% CI: 0.4 to 3.7%) in dehydrated group relative to control (standardized effect size of 0.20, 95% CI: −0.01 to 0.40). Percent dehydration of control group, exercise duration, exercise intensity and ambient temperature were entered in a hierarchical, weighted least-squares regression model to determine the predictors of the percent change in power output. Only percent dehydration was retained in the model, with a prediction equation consistent with a decline in power output of 3.0% for each percent loss in body mass above a threshold loss of 1.7%. CONCLUSION: Exercise-induced dehydration equal or greater than 2% body mass can significantly impair endurance performance in elite athletes as well as in amateur athletes racing for personal best times.
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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 | 0.025 | 0.057 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.015 | 0.055 |
| Bibliometrics | 0.005 | 0.005 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| 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".