Endurance Training - Physiological Effects

Physiological Effects

Long-term endurance training induces many physiological adaptations both centrally and peripherally mediated. Central cardiovascular adaptations include decreased heart rate, increased stroke volume of the heart, increased blood plasma, without any major changes in red blood cell count, which reduces blood viscosity and increased cardiac output as well as total mitochondrial volume in the muscle fibers used in the training (i.e. the thigh muscles in runners will have more mitochondria than the thigh muscles of swimmers). Mitochondria increase in both number and size and there are similar increases in myoglobin and oxidative enzymes. Adaptations of the peripheral include capillarization, that is an increase in the surface area that both the venous and arterial capillaries supply. This also allows for increased heat dissipation during strenuous exercise. The muscles heighten their glycogen and fat storing capabilities in endurance athletes in order to increase the length in time in which they can perform work. Endurance training primarily work the slow twitch (type 1) fibres and develop such fibres in their efficiency and resistance to fatigue. Catabolism also improves increasing the athletes capacity to use fat and glycogen stores as an energy source. These metabolic processes are known as glycogenolysis, glycolysis and lipolysis. There is higher efficiency in oxygen transport and distribution. In recent years it has been recognized that Oxidative Enzymes such as succinate dehydrogenase (SDH) that enable mitochondria to break down nutrients to form ATP increase by 2.5 times in well trained endurance athletes In addition to SDH, myoglobin, increase by 75-80% in well trained endurance athletes.