The Impact of Ambient Temperature on Physical Performance and Fatigue

Endurance of an athlete during physical exercise depends on many factors. One important factor is heat resulting from metabolic processes initiated to serve the increased energy demand during exercise. The hypothalamus in the brain is responsible for this thermoregulation aiming to transport heat from the body’s core to the periphery. When the body temperature rises or when humans exercise in hot environments, the blood brain barrier becomes more permeable to neurotransmitters due to histamine release because of heat stress. This gives serotonin, dopamine and noradrenaline access to enter and leave the brain and to affect levels of fatigue. In addition, this process of thermoregulation shows a diurnal rhythm promoted by the suprachiasmatic nucleus (SCN), which also is located in the hypothalamus. It is well known that humans adapt their physiology to increased energy demands and heat production in response to regular physical exercise. Physiological adaptations can, for example, be found at the level of the muscles, heart, and the vascular and respiratory system. This thesis aims to describe the impact of a high ambient temperature on physical performance and fatigue.