Primal Grow Pro As an example, we can consider the separation of muscle groups and body parts of a bodybuilder. A big problem arises when constantly training the same muscle group. Because of this, the emphasis shifts to local muscle fatigue and recovery. And this is good, because you can get a realistic picture of the reaction of the human body to physical activity and look at them from a global point of view. What stimulates muscle contraction? Muscles do not contract themselves. For contraction, they need electrical impulses, which means the central nervous system. The central nervous system, namely the autonomic nervous system consists of two branches: The sympathetic nervous system (SNS), the so-called "fight or run" branch. If an athlete wants to run fast, jump high or lift weights, he activates the sympathetic nervous system to help himself with this. Parasympathetic nervous system (PNS) is a branch for rest and ***imilation of food. To relax and recover, it is she who is activated. Thus, your nervous system must be in a balanced state. Want to train harder? One must learn to activate the sympathetic nervous system. But when it comes time to relax and get some sleep, the parasympathetic nervous system needs to work as it should. In connection with the above, the question arises: how do you track the balance of the nervous system? Heart Rate Variability Monitoring One of the best ways to track performance is to monitor heart rate variability. To do this, you can use one of the various applications and monitors that are available on the market. These systems alter the tiny time differences that occur between the contractions of your heart. They evaluate the changes in the activities of the SNA and PNS and give its ***essment.