Does Exercise Affect the Body's pH?

Each of the parts of the human body, from plasma to intracellular fluid, has a given normal pH value. One of the functions of homeostasis, or your body's ability to self-regulate, is to keep its relative acidity or alkalinity in check, just as it monitors temperature. Bodily activities such as exercise can dramatically affect the pH value. The precise effects vary, depending on the type of exercise.

source

AEROBIC VS. ANAEROBIC EXERCISE

You can divide exercise into two basic forms: aerobic and anaerobic. During aerobic exercise, your body draws on oxygen to help produce any energy necessary for the exercise. By contrast, anaerobic exercise is of such high intensity that the body cannot deliver oxygen throughout the body in time to make use of it energetically. Instead, your body derives energy from glucose by breaking down the sugar into pyruvate and further breaking this pyruvate into lactate. During especially intensive exercise, this process proves speedier than delivering the same amount of oxygen.

LACTIC ACID

A burst of anaerobic activity lasting up to three minutes can produce very high levels of lactate and lactic acid. As a result of this acid production, the pH value of the muscle cells sharply falls. Although the decreased pH level is far outside its normally ideal range, the sudden acidity serves to block continued production of pyruvate and lactate, as the glucose breakdown process cannot function as well in an acidic environment. As a result, the change in pH gives a signal to your body to slow down, saving it from overexertion or permanent muscle damage. Once the body slows down sufficiently, it can switch from anaerobic back to aerobic activity.

ACIDOSIS

If your body's pH level drops below about 7.4 it enters a state of acidosis, or excessive acidity. Should anaerobic exercise and the production of lactic acid trigger this extreme state, the low pH can have wide-ranging negative implications, due to the many bodily functions, such as protein manufacture, that rely on a neutral pH environment.

BUFFERS AND BALANCE

Buffers in the bloodstream help ensure that lactic acid production doesn't dramatically throw off the body's pH. These buffers are dissolved in the blood, allowing them to act throughout the body. The extra H+ ions that cause acidity are able to pass through cellular membranes, making it possible to regulate acidity from one cell to the next. In addition to the buffers in the blood, the kidneys serve to remove H+ ions, helping to raise pH and avoid acidosis. In addition, your breathing helps to regulate blood pH. Increased breathing during exercise helps counterbalance the heightened energetic demands by removing CO2 from the body and thereby neutralizing the pH level in the blood.