During intense exercise or other physical activity, breathing rates quicken to disperse oxygen throughout the body. When the muscles are working so hard that they are not getting enough oxygen quickly enough for the energy they need, the body uses glucose for energy. Pyruvate is a substance that breaks down glucose molecules to give the muscles energy to continue working. A build up of lactic acid is caused by pyruvate being changed to lactate in the muscles. This occurs when there is not enough oxygen to move the pyruvate through the body to be broken down because lactate also allows glucose to be converted into energy.
Lactate increases the acidity of the muscle tissues. This acidic environment makes it harder for the body to break down glucose for energy. The acidic environment helps the body protect itself from overexertion because it is more difficult for the muscles to keep functioning when there is a build up of lactic acid in the muscles.
A common misconception is that a build up of lactic acid in the muscles during a workout leads to soreness, but this is not the case. The muscles do often feel like they are burning when there is a build up of lactic acid during strenuous activity, which may encourage the person to cease physical activity and rest, but it is the strain and damage to the muscle cells that likely results in soreness. A few days of recuperation are often necessary after a strenuous workout.
Athletes and other individuals who work out at high intensities can often prevent a build up of lactic acid by altering their workout or training routines. Staying hydrated during exercise is extremely important, and allows the muscles to function at peak capacity. Incorporating muscle strengthening activities with cardiovascular exercise also helps because stronger muscles are able to work harder and for longer periods of time before turning to lactate to break down glucose.
Working out with an interval program is another way to teach the body to prevent excess lactic acid from building up. Interval training consists of doing several minutes of moderate physical activity, such as power walking or jogging, followed by shorter bursts of high-intensity activity, such as sprinting. Allowing the muscles to rest slightly between bouts of high-intensity activity prevents too much lactic acid from accumulating in the muscles.