Effect Of Beverage Temperature On Whole-body Heat Dissipation During Exercise-heat Stress In Older Men
Bibliographic record
Abstract
Inadequate fluid replacement during prolonged exercise in the heat can impair cardiovascular and thermoregulatory function. While regular fluid ingestion can mitigate this deterioration, studies show that relative to warm beverages, ingestion of cold drinks can reduce heat dissipation during exercise in young men. However, it is unclear if beverage temperature may have a similar effect in older adults. PURPOSE: We assessed the effect of cold (0 °C) and warm (37.5 °C) fluid ingestion on whole-body dry and evaporative heat exchange during exercise-heat stress in older men. METHODS: On separate days, six older men (mean [SD], age: 59 [3] years, VO2peak: 33.6 [3.7] mL/kg/min) performed four 15-min bouts of exercise at a fixed rate of metabolic heat production (200 W·m-2; to maintain a fixed thermal drive for heat loss), each separated by 15-min rest in the heat (40oC, ~15% RH). Before the first (Ex1) and third exercise (Ex3) bouts, participants consumed 5.2 g/kg of either cold or warm fluid over a ~ 10 min period. Rates (W·m-2) of whole-body total heat loss (dry + evaporative heat loss, via direct calorimetry), metabolic heat production (via indirect calorimetry) and change in core (rectal) temperature (ΔTrec, difference from pre-exercise rest) were measured continuously and expressed as peak responses (mean of final 5 minutes of the Ex1 and Ex3). Data were compared using a one-way ANOVA with Bonferroni post-hoc analysis (α = 0.05). RESULTS: No differences in whole-body dry (Ex1: -57 [7] and -56 [7]; Ex3: -59 [7] and -57 [7] W·m-2) and evaporative heat loss (Ex1: 202 [27] and 223 [16]; Ex3: 226 [16] and 229 [20] W·m-2) were observed between cold and warm beverages, respectively (all p > 0.05). Similarly, no significant change in whole-body total heat loss (Ex1: 145 [24] and 167 [17]; Ex3: 166 [15] and 172 [17] W·m-2) was observed between beverage conditions (p > 0.05). Consequently, ΔTrec (0.15 [0.07] and 0.23 [0.08]; Ex3 (0.49 [0.11] and 0.68 [0.19] °C), was not different between cold and warm fluid conditions, respectively (p > 0.05). CONCLUSION: We show that the contribution of whole-body dry and evaporative heat exchange on the resulting changes in whole-body total heat loss during exercise-heat stress was not affected by beverage temperature in older men. FUNDING: Natural Sciences and Engineering Research Council of Canada
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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".