In this lesson, we discuss the training stimulus. Now a stimulus is a specially designed exercise that evokes a specific physiological reaction in the athlete's organs or tissues. And the purpose is to strengthen those organs and tissues. The strength of the physiological response to a training stimulus depends on how much the body's homeostasis has been affected. A well designed training stimulus challenges the body's homeostasis in a very specific way, so relevant sport specific structural and functional redesign occurs. Now recall that temperature, salt, acid, nutrient and waste balance of the body's internal environment affects the ability of cells to do their job. Temperature and acidity of the body is of particular concern to the brain because these variables affect enzyme functioning. Now, enzymes are really delicate proteins structures that act as catalyst for the thousands of chemical reactions taking place during a training session or during the training, during the athlete's recovery, or during their day to day living. In essence, enzymes are essential to maintaining life. Now we've discussed homeostasis quite a bit already. Because this is a very important biological concept and there's a key to understanding how training works to improve the athletes performance. And in this lesson, we talk a lot more about the interaction between training and the effect it has on the body's homeostasis. A training session is a planned disturbance of homeostasis. The blue box here represents the range of conditions within the body where homeostasis is maintained. During a warm up, there is a slight improvement in the working efficiency of the athletes body due to the adjustments the brain makes to heart rate and other physiological functioning in response to the initial disturbance of homeostasis. The purpose of the warm up is to increase the physiological functioning of the body while remaining within the tolerable range for homeostasis. And here you see physiological functioning extend to the upper range of homeostasis as the warm up proceeds. The training session itself disturbs homeostasis by taking it slightly outside this tolerable range. The athlete's physiological functioning will gradually decline as the cell's resources are depleted. And depending on the intensity of the training session, the tissues of the organ structures are stressed and the cells can be slightly damaged. The athlete will feel the sensation of increasing fatigue that reflects the inability of the brain to maintain homeostasis. During recovery, between the training sessions, these resources are replenished back to the normal level. In other words, the internal environment of the body returns to homeostasis. Damaged cells are also repaired during recovery. Restoring homeostasis after a training session can take several hours. It depends on the intensity of the training session. If the time between training sessions are sufficient for full restoration to occur the body then enters into a super-compensation phase where structures such as enzymes are strengthened, so the athlete's physiological capacity improves just a little bit. And this is referred to as the training effect, each time super-compensation occurs, the structures of the body are functionally enhanced, making it slightly easier for the brain to mobilize resources and maintain homeostasis during the next training session. Now, if another training session does not occur within a couple of days, the body structure functioning will decline back to match the needs of the less active body. So when you've completed this lesson, you'll be able to discuss the physiological responses associated with the training session. You will understand the optimal timing of the next training stimulus and you'll be able to discuss the different types of stimulus variables that you can use to disturb homeostasis and induce the correct adaptation. And you'll be able to discuss methods you can use to measure the intensity of the training stimulus. So let's get started.
