Genetics is usually the main factor in hair growth, but exercising can also promote hair growth.  Exercising is a great way to maintain a healthy and properly functioning body.  Cardiovascular exercises allows for great circulation of blood throughout your entire body.  Blood circulation allows the transportation of nutrients and oxygen to hair follicles, which is essential for growth.  Also, it's great to exercise because it reduces stress, which also is a factor for stunted hair growth and also hair loss.  Stress increases cortisone, the hormone that is responsible for hair thinning and hair loss. Exercising is also good because it helps reduce stress by releasing serotonin.  Serotonin is a hormone that allows you to feel energized and happy.