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
Abdominal exercise on the lumbar spine, putting unwanted stress on the lower back. In addition, exaggerated abdominal exercise can cause respiratory problems. A study of twelve exercises concluded that no single exercise covered all abdominal muscles with high intensity and low compression. The benefit of focused training on the "deep core" muscles such as the transversus abdominis has been disputed, with some experts advocating a more comprehensive training regimen. Abdominal exercise Abdominal exercises are those that affect the abdominal muscles (colloquially known as the stomach muscles or "abs"). Abdominal exercises are useful for building the abdominal muscles. This is useful for improving