Preliminary Assessment Of Safe Initial Stay Times Over Consecutive Workdays For Younger And Older Men
Bibliographic record
Abstract
On the advice of regulatory agencies, workplaces rely on the use of work-rest allocations to limit elevations in core temperature (Tco) above 38 °C. However, no direction is provided on the continuous work time that can be performed (initial stay time; IST) before work-rest cycles are implemented. We recently generated estimates for ISTs for moderate-intensity work over consecutive days and showed similar responses in younger and older males. However, responses over consecutive days have yet to be assessed for heavy-intensity work, where greater age-related differences have been observed. PURPOSE: To determine IST for heavy-intensity work in the heat and evaluate if adjustments in ISTs are required for younger and older males for i) a second work bout following a lunch break and ii) a work bout performed the next day. METHODS: Eight younger and 10 older males performed 4-h of heavy-intensity treadmill walking (260 W·m−2 metabolic rate) in 26 °C wet-bulb globe temperature. Work continued until Tco reached 38 °C after which a work-rest allocation of 1:1 (starting with 30 min rest) was applied for the remainder of the work period. The protocol was repeated in the afternoon after a 1-h lunch break (22 °C), and the next morning. Core (rectal) temperature was measured continuously. RESULTS: The IST was significantly shorter in the afternoon (30 ± 9 min: p < 0.05) compared to the morning of day 1 (62 ± 25 min) and day 2 (75 ± 39 min), while responses did not differ between morning work (p = 0.15). Further, no differences were observed between younger and older males (p = 0.10). Peak and average Tco during work-rest allocations were greater in the afternoon compared to mornings of day 1 and day 2 (p < 0.05). Relative to their younger counterparts, peak (older: 38.47 ± 0.27 vs younger: 38.12 ± 0.16 °C) and average (older: 38.20 ± 0.20 vs younger: 37.87 ± 0.18 °C) Tco in older males were greater during the afternoon work-rest allocations (p < 0.05). CONCLUSION: Although ISTs were shorter in the afternoon following morning work, peak Tco and average Tco were significantly greater in older males relative to younger during the work-rest allocations in the afternoon session. Employers should aim to schedule heavy-intensity work in the morning to avoid sustained elevations in Tco and unsafe work behavior when working in the heat during afternoon periods. Supported by: Workplace Safety and Insurance Board (Ontario)
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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 | 0.002 |
| 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) | 0.002 | 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".