How Exercise Works

Muscles and Oxygen

If you are going to be exercising for more than a couple of minutes, your body needs to get oxygen to the muscles or the muscles will stop working. Just how much oxygen your muscles will use depends on two processes: getting blood to the muscles and extracting oxygen from the blood into the muscle tissue. Your working muscles can take oxygen out of the blood three times as well as your resting muscles. Your body has several ways to increase the flow of oxygen-rich blood to working muscle:

  • increased local blood flow to the working muscle
  • diversion of blood flow from nonessential organs to the working muscle
  • increased flow of blood from the heart (cardiac output)
  • increased rate and depth of breathing
  • increased unloading of oxygen from hemoglobin in working muscle

­ These mechanisms can increase the blood flow to your working muscle by almost five times. That means that the amount of oxygen available to the working muscle can be increased by almost 15 times!


Let's examine more closely how blood flow to working muscle can be increased.