So far, we have examined the endocrine and the autonomic nervous systems, and the role each plays in returning the body to and maintaining homeostasis. Now we'll delve into how the endocrine and the autonomic nervous systems relate to this complex condition referred to as overtraining. And we're specifically going to ask the question or answer the question, what is overtraining? This lesson lays the groundwork for the next lesson where we discuss useful methods for monitoring the danger signals for possible chronic fatigue and therefore overtraining. And following that we will delve deeper into the physiology of overtraining, so that you have a really solid insight into this very frustrating phenomenon. When an athlete is underperforming and you don't know why, suspect that chronic fatigue due to overtraining is the prime contributing factor. Unfortunately because we don't understand much about chronic fatigue, our knowledge about overtraining remains scant. Hans Selye's general adaptation frameworks suggest is likely due to too much training and insufficient recovery, that leads to a prolonged maladaption of the physiological systems and the structures as they try to adapt. The outcome is always a feeling of fatigue, there are sleep disturbances, there is lack of desire to train, and there are reoccurring respiratory infections. It is thought that fatigue is possibly related to an immune system, they can't keep pace with the necessary repair other damaged muscles and other tissues, due to overtraining. And we have talked a bit about fatigue theories, besides the immune system response. One red flag of possible chronic fatigue due to overtraining is unexplained underperformance. An athlete is underperforming and feeling constantly tired, they become very frustrated. And this will spur some to train harder and others to give up due to sagging self esteem. And the athlete struggles to complete training sessions at the required intensity. And recovery takes a lot longer than it should. Technical skills suffer partly due to fatigue and partly due to an inability to mentally focus. Now chronic fatigue due to overtraining is quite common. More than 60% of distance runners experience overtraining symptoms during their athletic careers. Around 50% of soccer players will have symptoms during a five month competitive season. Intense camp environments also play a contributing role. Almost a third of the enrollees in a six-week basketball training camp experience symptoms of overtraining. The overtraining phenomenon is likely to become even more common as sport places higher demands on the athlete's time and energy reserves at younger and younger ages. And there's no question that the human body has a remarkable ability to adapt. However, there is a limit to it's ability to cope with ongoing intense exercise. The human body has a particular problem successfully adapting to stress or highly repetitive activities for an extensive time as occurs when athlete specialize in one sport. We design to be movement generalists not specialist in a small number of movements. And sport, by its very nature, demands specificity of training. A good coach understands the fragility of the human body. Athletes can accomplish a remarkable physical feats, but there are limits. Successful training requires matching training so it does not successfully or excessively overextend the current capacity of the athletes physiological systems. So, in this lesson, we're going to discuss the training continuum. And examine the differences between the fatigue associated with acute overload, over-reaching and over-training. And we're going to take a look at some case histories that illustrate the seriousness of overtraining to the athlete's long term health. There are many symptoms of overtraining and we're going to examine some of the more useful indicators that you can use. And we'll also discuss over-reaching as a strategy to stimulate enhanced adaptations and how this can be employed in a older and more experience athletes, to more experience athlete's advantage if it is used cautiously. So, let's get started.