Circadian Rhythm Does Not Alter the Sweating Response to Exercise in Thermoneutral and Warm Ambient Temperatures
Bibliographic record
Abstract
The present study sought to determine whether the diurnal fluctuation in core temperature alters the sweating response to exercise in thermoneutral (23°C) and warm (33°C) environments. Six healthy males exercised on a semi‐recumbent ergometer at a fixed evaporative requirement for heat balance (200W/m 2 ) for 60 min at two different times of day and two ambient temperatures matched for absolute humidity (1.3 kPa); i) 0800h/23°C, ii) 0800h/33°C, iii) 1600h/23°C, and iv) 1600h/33°C. Esophageal temperature (T es ), mean body temperature (T b ), local sweat rate (LSR) measured at the arm and upper back, and whole body sweat loss (WBSL) were measured. Resting absolute T es was higher at 1600h compared to 0800h at 23°C (0800h: 36.7±0.2°C, 1600h: 36.9±0.2°C; P=0.04) and 33°C (0800h: 36.6±0.2°C, 1600h 36.9±0.2°C; P=0.005). Similarly, end‐exercise (steady‐state) absolute T es was higher at 1600h relative to 0800h at 23°C (0800h: 37.4±0.2°C, 1600h: 37.6±0.2°C; P=0.04) and 33°C (0800h: 37.0±0.2°C, 1600h 37.2±0.2°C; P=0.01). However the change in T es was similar irrespective of the time of day at both 23°C (0800h: 0.7±0.1°C, 1600h: 0.7±0.2°C; P=0.37) and 33°C (0800h: 0.4±0.1°C, 1600h: 0.3±0.1°C; P=0.35). Further, mean steady‐state LSR of arm and back after 60 min of exercise was similar irrespective of time at both 23°C (0800h: 0.66±0.06 mg/cm 2 /min, 1600h: 0.65±0.13 mg/cm 2 /min; P=0.74) and 33°C (0800h: 0.62±0.11 mg/cm 2 /min, 1600 h: 0.58±0.11 mg/cm 2 /min, P=0.50). Likewise, WBSL at steady‐state (46 to 60 min) was similar between morning and afternoon trials at 23°C (0800h: 156±28 g, 1600h: 162±36 g; P=0.38) and 33°C (0800h: 147±29 g, 1600h: 158±34 g, P=0.55). While sweating commenced prior to exercise in 33°C, the onset threshold for sweating occurred at a higher T b at 1600h compared to 800h at 23°C (0800h: 35.6±0.1°C, 1600h 35.9±0.2°C; P=0.03), however the change in T b was similar at 23°C regardless of time of day (0800h: 0.14±0.07°C, 1600h 0.17±0.12°C; P=0.47). Lastly, sudomotor thermosensitivity (LSR‐T b ) was similar at both 23°C (0800h: 0.80±0.26 mg/cm 2 /min/°C, 1600h: 0.82±0.30 mg/cm 2 /min/°C; P=0.80) and 33°C (0800h: 0.81±0.18 mg/cm 2 /min, 1600h: 0.90±0.40 mg/cm 2 /min, P=0.87). Taken together, preliminary data suggests the difference in absolute core temperature (~0.3°C) associated with diurnal fluctuation does not alter the sweating response at a fixed evaporative requirement for heat balance in both thermoneutral and warm conditions. Support or Funding Information N.R. was supported by an NSERC Postgraduate Scholarship‐Doctoral and a University of Ottawa Excellence Scholarship. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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".