Wind sprints are a type of aerobic exercise designed to increase strength and cardiovascular health. They are performed while running at a moderate to easy pace, then sprinting hard for several seconds, and finally returning to the moderate running pace. Wind sprints are designed to ramp up the heart rate quickly and make the muscles work hard for a short amount of time, then sustain the work at a moderate pace after the sprint. The name does not mean the runner runs against the wind, as some people believe; it may have been named as such because the runner is likely to become "winded," or tired, during this exercise.
To perform wind sprints, a runner should start by running at a moderate pace for several minutes. This period is important to get the body ready for more athletic strain and to loosen the muscles to prevent injuries. The heart rate will rise to a moderate level during this phase, again preparing the body for more strenuous exercise. After about 10 to 15 minutes of running at this moderate pace, it is time to begin doing wind sprints. The runner will increase his or her running speed to a sprint, but not necessarily to a maximum speed. This sprint should last from 10 to 30 seconds, and then the runner should reduce his or her speed back down to the moderate pace.
It is important to keep running at the moderate pace after the wind sprints and to avoid slowing down or stopping altogether. It is during this phase of the wind sprints that the muscles are forced to continue to work and therefore become stronger and more consistent. The lungs and heart must also continue to work hard, meaning the body will improve its oxygen delivery to the muscles, thereby promoting healthier muscle function. Wind sprints should be repeated several times during a period of running, and as the runner becomes more used to the sprints, the sprint times should be increased as well as the sprint frequency during the run.
Once the sprinting period is finished, the runner should do a cool-down period at a slow to moderate pace. He or she should then spend a fair amount of time stretching the muscles of the legs and lower back to help prevent injury and keep the muscles limber and healthy. People who are new to this exercise should start with fewer sprints at slower speeds to prevent injury.