The soreness you may feel 24 hours after a hard workout cannot be prevented by warming up or stretching before exercise nor by cooling down after you're through.
It can be prevented by toughening your muscles: exercising regularly and energetically, remembering to stop when your muscles start to burn.
People who work out on a regular basis do not suffer from muscle soreness, unless they exercise too vigorously or for a very long time.
They will also experience soreness when they use muscles not normally used.
For instance, a runner may end up with sore arm and back muscles after painting a house.
If your muscle soreness is widespread, it is probably a normal response to very vigorous exercise.
On the other hand, if your muscle soreness is confined to a small area, you probably have an injury and should not exercise again until the soreness goes away.
Muscles contain two types of fibers: white fibers that govern strength and speed, and red fibers that govern endurance. The white fibers are classified as those that need oxygen to function and those that do not.
Most of the damage that can result from exercising too vigorously occurs in the white strength-and-speed fibers that don't need oxygen.
While warming up before exercise does increase the oxygen supply to your muscles, it does not prevent muscle soreness; your injured white fibers don't require the increased oxygen that a warm-up supplies.
Stretching before a workout and cooling down afterward won't help prevent muscle soreness either, since these activities don't toughen the fibers.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.