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\nRationale<\/strong>
\nMonitoring 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.
\nObjectives<\/strong>
\nThe objective of this study was to assess whether sex modifies the relationship between PeSI and PSI.
\nMethods<\/strong>
\nThirty-four adults (15 females) walked on a treadmill (moderate intensity; ~200\u2009W\/m2) for 180\u2009min or until termination (volitional fatigue, rectal temperature \u226539.5\u00b0C) in 16\u00b0C, 24\u00b0C, 28\u00b0C, and 32\u00b0C wet-bulb globe temperatures. Rectal temperature and heart rate were recorded to calculate PSI (0\u201310 scale). Rating of perceived exertion and thermal sensation were recorded to calculate PeSI (0\u201310 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\u2013Altman analysis. Mean absolute error between measures was calculated by summing absolute errors between the PeSI and the PSI and dividing by the sample size.
\nFindings<\/strong>
\nPSI increased with PeSI (p\u2009<\u20090.01) but the slope of this relation was not different between males and females (p\u2009=\u20090.83). Mean bias between PSI and PeSI was small (\u22120.4 points), but the 95% LoA (\u22123.5 to 2.7 points) and mean absolute error were wide (1.3 points).
\nImpact<\/strong>
\nOur 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.<\/p>\n
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