Exercise physiology loss of integrity to the blood brain barrier. Hyperthermia also can lower cerebral blood flow, and raise brain temperature. Researchers once attributed fatigue to a build-up of lactic acid in muscles. However, this is no longer believed. Rather, lactate may stop muscle fatigue by keeping muscles fully responding to nerve signals. The available oxygen and energy supply, and disturbances of muscle ion homeostasis are the main factor determining exercise performance, at least during brief very intense exercise. Each muscle contraction involves an action potential that activates voltage sensors, and so releases Ca ions from the muscle fibre’s sarcoplasmic reticulum. The
Exercise and androgen levels during the match, but returned to baseline after 45 minutes rest. Aerobic exercise in Japanese rats done on a rodent treadmill doubled local concentrations of DHT in calf muscles as assessed by protein assay. After intense aerobic effort, high endurance athletes were also found to have lower free testosterone the next day. In prolonged endurance exercise, such as a marathon, levels ultimately decrease. Similarly, DHT drops, while adrenal androgen and cortisol will increase with the stress response. It is unknown if anaerobic training changes individual hormone profiles, or if conditioned athletes in studies self-selected because of physiologic predisposition to athletic