15 Aug. 2015 – Lebanon and the whole universe are facing waves of heat during summer season. This weather can directly and negatively affect the athlete’s training and competition.
The human body’s core temperature varies from day to day, and from time to time, but these fluctuations are small, usually no more than 1.0oC. Our body temperature is regulated at about 37oC +/- 1oC.
There are two sources of heat that can influence the body: External (climatic) and internal (metabolic). Heavy exercise, illness, and not only hot and humid but also cold and windy environments alter body temperature outside the normal range.
Metabolic heat is produced by exercise and it increases the thermal load while evaporation decreases the load to maintain a heat balance.
A large part of the energy that the body generates is degraded to heat. All body tissues produce heat that can be used to maintain body core temperature. When heat production exceeds the body’s heat loss, body temperature rises.
Intense exercise may increase the metabolic energy expenditure 20 to 25 times over resting levels. No more than 25% of this energy is utilized for muscular movement—the remainder is heat, which the body must dissipate.
Metabolic heat is transferred by convection from working muscles to the blood stream, and thence to the body’s core. Without adaptive mechanisms, even moderate exercise would elevate body temperature by 1oC every 5–6 minutes; thus, exercise would be limited to no more than 20–30 minutes before heat stress fatigue or life-threatening hyperthermia intervened.
In fact, the body is able to respond to a heat load through a variety of physiologic mechanisms: sweat rate, body and skin blood flow shifts, cardiac output, respiratory rate, and a sensation of heat intensity. Well-trained endurance athletes can sustain a core temperature of 39o to 41oC for prolonged periods.
The muscles’ energy systems become more chemically effective with a small rise in muscle temperature. However, a critical thermal maximum is reached at 42oC (108oF), so there is a limited safety margin at intense levels of exercise. Heavier athletes run a higher risk of overheating than lighter athletes when exercising at the same rate.
A proper hydration is key to prevent Heat Related Disorders.
See Related Article: Heat Related Disorders: Signs, Treatments and Prevention
Documents Source: IAAF
The post How the heat can influence the Body appeared first on Sports 961.
