Agreement between measured and self‐reported physiological strain in males and females during simulated occupational heat stress

• Published in: American journal of industrial medicine Vol. 67; no. 5; pp. 466 - 473
• Main Authors: O'Connor, Fergus K., Meade, Robert D., Notley, Sean R., Ioannou, Leonidas G., Flouris, Andreas D., Kenny, Glen P.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-05-2024
• Subjects: Adult; Bias; Body Temperature - physiology; Error analysis; exercise; Exercise Test; Female; female physiology; Females; Heart rate; Heart Rate - physiology; Heat; Heat stress; Heat Stress Disorders; Heat tolerance; Heat-Shock Response; Hot Temperature; Humans; Male; Males; Monitoring; Occupational exposure; Occupational health; Occupational Stress; perceptual strain index; physiological strain index; Physiology; Rectum; Self Report; Sex; Strain; Stress, Physiological - physiology; Temperature effects; thermoregulation; worker physiology; physiological strain index; female physiology; exercise; worker physiology; thermoregulation; perceptual strain index
• ISSN: 0271-3586; 1097-0274
• DOI: 10.1002/ajim.23580

Rationale
Monitoring physiological strain is recommended to safeguard workers during heat exposure, but is logistically challenging. The perceptual strain index (PeSI) is a subjective estimate thought to reflect the physiological strain index (PSI) that requires no physiological monitoring. However, sex is known to influence perceptions of heat stress, potentially limiting the utility of the PeSI.
Objectives
The objective of this study was to assess whether sex modifies the relationship between PeSI and PSI.
Methods
Thirty‐four adults (15 females) walked on a treadmill (moderate intensity; ~200 W/m2) for 180 min or until termination (volitional fatigue, rectal temperature ≥39.5°C) in 16°C, 24°C, 28°C, and 32°C wet‐bulb globe temperatures. Rectal temperature and heart rate were recorded to calculate PSI (0–10 scale). Rating of perceived exertion and thermal sensation were recorded to calculate PeSI (0–10 scale). Relationships between PSI and PeSI were evaluated via linear mixed models. Mean bias (95% limits of agreement [LoA]) between PSI and PeSI was assessed via Bland–Altman analysis. Mean absolute error between measures was calculated by summing absolute errors between the PeSI and the PSI and dividing by the sample size.
Findings
PSI increased with PeSI (p < 0.01) but the slope of this relation was not different between males and females (p = 0.83). Mean bias between PSI and PeSI was small (−0.4 points), but the 95% LoA (−3.5 to 2.7 points) and mean absolute error were wide (1.3 points).
Impact
Our findings indicate that sex does not appreciably impact the agreement between the PeSI and PSI during simulated occupational heat stress. The PeSI is not a suitable surrogate for the PSI in either male or female workers.