Does Attenuated Skin Blood Flow Lower Sweat Rate and Thereby the Critical Environmental Limit for Heat Balance?
Bibliographic record
Abstract
Attenuated skin blood flow (SkBF) is often assumed to critically impair core temperature (T c ) regulation. Recent evidence has shown that a profound pharmacologically‐induced attenuation of SkBF leads to a reduction in local sweat rate. Whether attenuated SkBF to a level more commonly observed in aged or diseased populations leads to decrements in sweat rate, and consequently, a reduction in heat loss potential is presently unknown. Therefore, the purpose of the present study was to test the hypothesis that attenuated SkBF would lead to lower sweat rate and heat loss potential, defined as the critical ambient vapour pressure (P crit ) at which core temperature (T c ) inflected, while maintenance of a high SkBF would preserve sweat rate and heat loss potential. Seven healthy males (28±4 y) completed the protocol, which consisted of non‐encapsulated passive heat exposure (41°C), while ambient vapour pressure increased by 0.17 kPa (~2% RH) from 2.57 to a maximum of 5.95 kPa every 6 min until an upward inflection in T c occurred. Three separate treatments elicited changes in plasma volume (ΔPV) with the goal of achieving three distinct levels of SkBF: control (CON), diuretic‐induced iso‐osmotic dehydration to lower SkBF (DEH), and continuous saline infusion to maintain SkBF (SAL). T c , mean skin temperature (T sk ), heart rate (HR), mean laser‐Doppler flux (forearm, thigh; LDF mean ), mean local sweat rate (LSR mean ), and metabolic rate were measured. In DEH, a −14.2 ± 5.7% ΔPV resulted in a ~20% lower LDF mean (DEH: 139 ± 23, CON: 176 ± 22, SAL: 186 ± 22 PU; P = 0.034). However, LSR mean and whole‐body sweat losses were unaffected by treatment (P > 0.482). P crit for T c was similar between treatments (CON: 5.05 ± 0.30, DEH: 4.93 ± 0.16, SAL: 5.12 ± 0.10 kPa; P = 0.166). Further, no differences were observed in the T sk ‐T a gradient, metabolic rate, and changes in T c (P > 0.197). In conclusion, a physiological reduction in SkBF consistent with those reported in the elderly and diseased populations alters neither local and whole‐body sweating nor heat loss potential during non‐encapsulated passive heat stress. Support or Funding Information Funded by National Institutes of Health GM068865 and Department of Defense W81XWH‐12‐1‐0152 (CGC), and a Natural Sciences and Engineering Research Council Discovery Grant #386143‐2010 (OJ).
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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 | 0.001 |
| 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".