Effect of Hyperhydration on Performance during Prolonged Cycling in a Temperate Environment When Fluid is Consumed during Exercise
Bibliographic record
Abstract
Taken as a whole, research shows that, compared with pre-exercise euhydration (PEE), pre-exercise hyperhydration (PEH) improves endurance performance (EP) during moderate-duration exercise (18–105 min) conducted in hot ambient temperatures and this, independently of whether or not fluids are ingested during exercise. In a temperate climate, it has been shown that PEH enhances EP compared with PEE during an ∼ 2 h long cycling period in which no fluids are ingested. It still unclear whether PEH may improve EP compared with PEE during a mo derate-duration exercise conducted in a temperate climate when fluid is consumed during exercise. It is possible that the weak thermal and cardiovascular stress imposed on the body due to the nature of the environment, combined with the ingestion of fluid during exercise, which delays the attainment of the critical level of dehydration deleterious for EP, may render the surplus of fluid provided by PEH useless. PURPOSE: To compare the effect of PEH to a state of PEE on EP during a 2-h cycling exercise conducted at 26.5 °C, 55% RH, when fluid is ingested during exercise. METHODS: Using a randomized, crossover experimental design, 8 trained subjects underwent either an hyperhydration (26 ml/kg bodyweight [BW] of water with 1.2 g glycerol/kg BW [to maximize fluid retention]) or waiting period of 80 min, immediately followed by 2 h of cycling at 65% Vo2 max, which was interspersed by 5 2-min intervals at 80% Vo2 max. Following the cycling period, subjects underwent an incremental cycling test to exhaustion. During exercise, subjects drank 2.5 ml of sports drink/kg BW every 20 min, up to min 100. Heart rate, rectal temperature, perceived exertion, perceived heat-stress and perceived thirst were measured every 20 min during the 2 h cycling bout. During the cycling test, heart rate and rectal temperature were measured every 3 min. RESULTS: Subjects started the exercise during PEH and PEE hyperhydrated (17.0 ± 1.4 ml/kg BW) and euhydrated, respectively. During PEH and PEE, respectively, fluid ingestion during exercise replaced 36.0 ± 3.6% and 39.2 ± 5.3% of the sweat losses (P >0.05). PEH decreased (P <0.05) perceived thirst during the 2 h cycling exercise, but had no effect (P >0.05) on heart rate, rectal temperature, sweat rate, perceived exertion or perceived heat-stress. During the cycling test, PEH had no effect on heart rate or rectal temperature, nor on the time to exhaustion (PEH: 12.6 ± 1.4; PEE: 11.6 ±1.0 min). CONCLUSION: It is not beneficial to hyperhydrate before undergoing a moderate-duration (≤ 2 h), moderately intense (≤ 65% Vo2 max) exercise in a temperate environment (≤ 26.5 °C) when fluid is replaced at a rate ≥ 40% of sweat losses during exercise.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".