The anticipatory regulation of fatigue in exercise

The development of fatigue during exercise has been studied for over a century and although many attempts have been made to identify the causative factors, the process by which fatigue develops is still not clearly understood. There has been much research describing the relationship between heat stress, energy availability, perception, cardiovascular perturbations, hydration, and a host of other factors impinging on the development of fatigue during exercise. Until recently it was presumed that the development of fatigue during exercise was a process moving toward system collapse. Rather, it is now clear that fatigue can also be thought of as being a process which protects the body from physiological catastrophe rather than moving toward it. In this sense it is useful to approach the understanding of fatigue by attempting to examine the potential inputs that might be used by the body to regulate rather than limit performance. To this end, this chapter will explore the possible inputs which might be available to the body as a way of regulating the fatigue process and anticipating the effort required to successfully complete a given exercise task and avoid cellular catastrophe. The areas which will be discussed are the inherent differences between constant load and self-paced exercise, energy availability, thermoregulation and effort sense as possible inputs for the anticipatory regulation of fatigue in exercise.