It is well established that in prolonged endurance events, in the absence of carbohydrate feeding, the muscle glycogen pool may become depleted to the point where it limits the sustainable exercise intensity. However, in trained athletes who have greater reliance on fatty acid metabolism and who also have larger muscle glycogen stores, this limitation is overcome to a certain extent, or would only occur at higher absolute work intensities.
So, training adaptation and nutritional intervention may substantially alter the metabolic limitations or responses to exercise, and Sport and Exercise Nutritionists should have an understanding of these elements. The study of exercise biochemistry has not only helped our understanding of the interaction between exercise intensity/duration and substrate utilisation, but also provided great insight into the metabolic responses to environmental stresses such as heat, cold and altitude. It has also aided our understanding of the nature and time course of adaptations in metabolism that occur with exercise training. All these effects may subsequently alter nutritional requirements during exercise. By utilising knowledge of exercise biochemistry one can track metabolic responses to feeding, interpret gender differences in metabolism, and devise a variety of physical activity and nutritional approaches to weight loss/gain.
It is probable that new knowledge in this area will ultimately support or refute current recommended practices in training and dietary intake strategies.