Effect Of Beverage Temperature On The Relation Between Perceptual And Physiological Strain During Exercise-heat Stress
Bibliographic record
Abstract
To safeguard individuals who work in the heat, it is recommended to monitor core temperature and heart rate (HR), albeit these measurements can be logistically challenging in real-life scenarios. The perceptual strain index (PeSI, derived from measures of rating of perceived exertion (RPE) and thermal sensation (Ts)) requires no direct monitoring, and is thought to reflect the physiological strain index (PSI). Regular water ingestion is recommended during work in the heat to maintain hydration status and mitigate increases in core temperature. However, it remains unclear if beverage temperature influences a worker’s perception of heat strain. While the ingestion of cold fluid is commonly advised, workers may consume beverages that have been heated by the warm environment. PURPOSE: To assess the effect of beverage temperature on the relation between PeSI and PSI during intermittent work in the heat. METHODS: Twenty adults (10 females, mean [SD], age: 23 [3] years, VO2peak: 39.9 [6.0] mL/kg/min) performed four 15-min bouts of moderate-intensity (fixed metabolic heat production: 200 W/m2) cycling in the heat (400C, 15% RH), each separated by a 15-min rest. On separate days, participants consumed 5.2 g/kg of either cold (ice-slurry, 00C) or warm fluid (37.50C) before the first and third exercise bout. At the end of each exercise bout, rectal temperature (Trec) and HR were recorded to calculate PSI (0-10 scale), and RPE and Ts were recorded to calculate PeSI (0-10 scale). Trec, HR, Ts and RPE were compared via two-way ANOVA. Relations between PSI, PeSI and beverage temperature were evaluated via linear mixed models. Mean bias (95% limits of agreement [LoA]) between PSI and PeSI was assessed via Bland-Altman analysis. RESULTS: Trec, HR, Ts and RPE increased over time (all P<0.001) but were not influenced by beverage temperature (all P≥0.09). While PeSI increased with PSI (P<0.001), no differences were observed between cold and warm fluid ingestion (P=0.26). However, mean bias [95% LoA] between PSI and PeSI were large in both the cold (-2.1 [-5.7 - 1.5]) and warm fluid condition (-1.8 [-4.8 - 1.2]). CONCLUSIONS: While beverage temperature did not influence the association between PeSI and PSI, we showed that PeSI does not accurately reflect the level of physiological strain experienced by workers performing their duties in the heat. Natural Sciences and Engineering Research Council of Canada and Mitacs
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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 | 0.001 | 0.003 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".