Exercise-Induced Dehydration Reduces Sweat Rate Only After it Reaches Elevated Levels Similar to When Euhydrated
Bibliographic record
Abstract
It is well known that skin blood flow (SkBF) decreases during exercise-induced dehydration. However, there remains disagreement relating to the effects of exercise-induced dehydration on the sweating response. Some studies report a decrease in whole-body sweating during exercise-induced dehydration, whereas others report no change. Furthermore, those studies that do report a decrease fail to determine how these lower sweat rates are attained. PURPOSE: To determine whether dehydration incurred during exercise limits the steady-state level of local sweat rate (LSR), or if it results in a progressive reduction in LSR from elevated levels achieved prior to dehydration METHODS: 5 active males (21-31 yrs) performed 120 min of cycling exercise at a fixed external workload of 120 W, in a thermal chamber maintained at 42°C and 20% relative humidity. Exercise was performed with (HYD) and without (DEHY) fluid replacement. LSR, SkBF and esophageal temperature (Tes) were recorded continuously. RESULTS: Body weight decreased by 3.9±1.3 % during DEHY, whereas body weight was maintained within 0.4±0.4 % (p≤0.05) during HYD. After 60 min of exercise, LSR (1.63±0.77 mg/min/cm2 vs. 1.49±0.35 mg/min/cm2, p=0.493) and SkBF (58.8±16.7 pu vs. 57.9 ± 13.0 pu, p=0.347) were not significantly different between DEHY and HYD respectively. However, both LSR and SkBF decreased during the subsequent 60 min of exercise during DEHY while they remained at an elevated steady-state value during HYD (p≤0.05). At the end of 120 min of exercise, LSR (1.44±0.56 mg/min/cm2 vs. 1.69±0.52 mg/min/cm2, p≤0.05) and SkBF (48.9±10.0 pu vs. 55.2 ± 7.9 pu, p≤0.05) were significantly lower during DEHY compared to HYD. The reduced LSR and SkBF were paralleled by a greater rate of increase in Tes during the second hour of exercise for DEHY (0.0135±0.0067°C/min) compared to HYD (0.0061±0.0050°C/min, p≤0.05). Consequently, Tes was greater at the end of DEHY (39.04±0.52°C) compared to HYD (37.88±0.45°C, p≤0.05). CONCLUSION: Exercise-induced dehydration did not limit the steady-state level of LSR attained. Rather, it caused a progressive decrease in LSR only during the final 60 min of exercise after reaching levels similar to HYD. Funding support: NSERC grant held by Dr. G.P. Kenny.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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 | 0.000 | 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".