Sex differences in thermophysiological responses of elderly to low-intensity exercise during uncompensable heat strain

• Published in: European journal of applied physiology 2024-08, Vol.124 (8), p.2451-2459
• Main Authors: Daanen, Hein A. M., Dijkstra, Iris, Abbink, Emma, de Jong, Iris J., Wolf, S. Tony, Bongers, Coen C. W. G., Hondema, Laurens S., Eijsvogels, Thijs M. H., Kingma, Boris R. M.
• Format: Article
• Language: English
• Subjects: Air temperature; Biomedical and Life Sciences; Biomedicine; Body temperature; Females; Gender differences; Heart rate; Heat; Human Physiology; Humidity; Males; Occupational Medicine/Industrial Medicine; Original; Original Article; Relative humidity; Sensation; Sex differences; Sports Medicine; Sweat; Temperature
• ISSN: 1439-6319; 1439-6327; 1439-6327
• DOI: 10.1007/s00421-024-05457-8

Purpose The rising frequency of extreme heat events poses an escalating threat of heat-related illnesses and fatalities, placing an additional strain on global healthcare systems. Whether the risk of heat-related issues is sex specific, particularly among the elderly, remains uncertain. Methods 16 men and 15 women of similar age (69 ± 5 years) were exposed to an air temperature of 39.1 ± 0.3 °C and a relative humidity (RH) of 25.1 ± 1.9%, during 20 min of seated rest and at least 40 min of low-intensity (10 W) cycling exercise. RH was gradually increased by 2% every 5 min starting at minute 30. We measured sweat rate, heart rate, thermal sensation, and the rise in gastrointestinal temperature (Tgi) and skin temperature (Tsk). Results Tgi consistently increased from minute 30 to 60, with no significant difference between females and males (0.012 ± 0.004 °C/min vs. 0.011 ± 0.005 °C/min; p  = 0.64). Similarly, Tsk increase did not differ between females and males (0.044 ± 0.007 °C/min vs. 0.038 ± 0.011 °C/min; p  = 0.07). Females exhibited lower sweat rates than males (0.29 ± 0.06 vs. 0.45 ± 0.14 mg/m 2 /min; p