The twin challenges of heat stress and dehydration during firefighting contribute to high levels of cardiovascular strain which plays an important role in triggering sudden cardiac events. This study aimed to identify the independent and combined effects of heat stress and dehydration on the function of the cardiovascular system while conducting intermittent work in PPE (Personal Protective Equipment). In order to do this, a standardized exercise protocol was followed by a group of young fit men who were the participants. Each trial or intermittent exercise lasted 100min but the degree of heat stress and dehydration were altered through the amount of clothing worn and fluid provided. This created four experimental conditions: Euhydrated heat
