Effects of Low Oxygen Levels on Heat Stress and Work Endurance in Healthy Men Aged 18 to 70 Under Simulated Altitude Conditions

What This Trial Is About

Extreme heat events are becoming more frequent and intense, increasing the risk of heat-related illnesses for workers in hot environments. This study investigates whether low oxygen levels, simulating high altitude, increase physiological strain during moderate-intensity work in the heat for healthy young and older men. The research aims to determine if current heat-stress guidelines based on normal oxygen conditions remain protective when combined with hypoxia. Participants will complete two simulated heat exposure sessions one under normal oxygen levels and one with reduced oxygen simulating about 3000 meters altitude. Both sessions involve treadmill walking in a hot environment 37.50C, 35% relative humidity at moderate intensity until reaching age-specific initial stay times. After reaching this point, participants will follow prescribed work-rest cycles and then have seated recovery. During the study, researchers will monitor core temperature, heart rate, skin temperature, oxygen levels, hydration, perceptual responses, mood, environmental stress symptoms, and cognitive function. They will assess these measures during up to 240 minutes of work and a 1-hour recovery. The primary outcome is total work volume during the heat exposure. This comprehensive monitoring will help clarify if existing heat-stress recommendations need adjustment for combined heat and hypoxia exposure.

Working in the Heat at Simulated Altitude: Effects of Normobaric Hypoxia on Physiological Strain