A Lower Heat Activated Sweat Gland Density in Larger Individuals Does Not Impair Local Sweat Rates During Hot and Humid Heat Stress
Bibliographic record
Abstract
While the absolute number of sweat glands is primarily determined in utero , a larger body surface area (BSA) will naturally reduce the density of sweat glands per surface area which may compromise sweat rate per unit BSA, and consequently the maximal skin surface sweat coverage (i.e. skin wettedness: ω max ) during exercise in a hot/humid environment. The purpose of the present study was to compare the heat activated sweat gland density (HASGD), sweat gland output (SGO), local sweat rate (LSR) and ω max between groups differing greatly in BSA during hot and humid active heat stress. Twelve participants separated into two groups based on body size (Small (SM): n=6, 65±6 kg, 1.8±0.1 m 2 ; Large (LG): n=6, 102±13 kg, 2.3±0.1 m 2 ) exercised on an upright cycle ergometer at an evaporative heat balance requirement (E req ) of 240 W/m 2 and 290 W/m 2 for up to 75 min at 36°C, 70% RH. LSR of the upper back was measured throughout and expressed relative to surface area (mg/cm 2 /min). HASGD in number of sweat glands per cm 2 (glands/cm 2 ) was measured medially to LSR using the starch iodine technique every 15 minutes and averaged throughout the trial. Mean SGO was derived from the division of LSR and mean HASGD, and expressed as μg/gland/min. On a separate occasion ω max was measured using a humidity‐ramp protocol (increase of 0.3 kPa from 2.3 kPa every 7.5‐min) during exercise at a fixed external workload of 100W at 36°C until an inflection of esophageal temperature was observed. LSR was similar at 240 W/m 2 (SM: 1.24±0.24; LG: 1.40±0.47 mg/cm 2 /min, P =0.25) and 290 W/m 2 (SM: 1.36±0.18; LG: 1.36±0.36 mg/cm 2 /min, P =0.48). HASGD was greater in SM compared to LG group at 240 W/m 2 (SM: 67±12; LG: 55±6 glands/cm 2 , P =0.03) and 290 W/m 2 (SM: 73±9; LG: 57±11 glands/cm 2 , P <0.01). SGO was trending to be greater in the LG group at 240 W/m 2 (SM: 18.6±5.0; LG: 25.2±10.2 μg/gland/min, P =0.10) while significantly greater in the LG group at 290 W/m 2 (SM: 17.3±1.6; LG: 21.2±5.7 μg/gland/min, P =0.03). On the other hand, ω max was not different between groups (SM: 0.82±0.16; LG: 0.72±0.07, P =0.13). In conclusion, a lower HASGD in people with a greater BSA is compensated by a greater SGO to yield a similar LSR up to an E req of 290 W/m 2 and a similar ω max . Future research should attempt to assess how even greater reductions in HASGD due to disproportionally larger differences in BSA (ie morbid obesity) compromise LSR, ω max , and therefore the level of heat stress that can be physiologically compensated. Support or Funding Information Supported by a NSERC Discovery Grant (P. Imbeault & O. Jay)
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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) | 0.000 | 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) | 0.003 | 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".