The heat tolerance test: An efficient screening tool for evaluating susceptibility to heat

Context: Individuals in the population who are not able to sustain heat and whose body temperature will start rising earlier and at a higher rate than that of others, under the same conditions, are defined as "heat intolerant." Objectives: The applicability of the heat tolerance test (HTT) in identifying individuals' tolerance/intolerance to heat is presented. Setting: HTT is performed according to the following protocol: 120 minutes exposure to 40°C and 40% relative humidity in a climatic chamber while walking on a treadmill, dressed in shorts and T-shirt, at a pace of 5 km/h and 2% elevation. Rectal temperature and heart rate are continuously monitored, and sweat rate is calculated. Results and Conclusion: The HTT that is based on controlled exposure to an exercise-heat stress is an applicable and an efficient tool in differentiating between a temporary and permanent state of heat susceptibility.