There are two types of exercise-related muscle soreness. Immediate muscle soreness quickly dissipates and is the pain you feel during, or immediately after, exercise. Delayed muscle soreness signals a natural adaptive process that the body initiates following intense exercise. This type of muscle soreness manifests itself 24 to 48 hours after the exercise session and spontaneously decreases after 72 hours. Numerous studies have been conducted to determine the cause of delayed muscle soreness. The most current consensus attributes this condition to microscopic tears in the muscle and surrounding connective tissue following eccentric exercise. A muscle contracts eccentrically when it lengthens under tension during exercise. For example, during a biceps curl, the biceps muscle shortens during the concentric lifting phase and lengthens during the eccentric lowering phase. Eccentric contractions also occur during aerobic activity, such as downhill running, in which the quadriceps muscle repeatedly lengthens against gravity to lower the center of mass and aid in shock absorption. Exercisers who experience delayed muscle soreness include conditioned individuals who increase the intensity, frequency or duration of their workouts, or participate in an activity with which they are unfamiliar. Beginning exercisers, or those who have undergone a significant lapse in training, frequently experience soreness when starting or re-engaging in an exercise regimen. Studies attempting to identify the best methods to alleviate delayed muscle soreness are almost as abundant as the number of studies conducted to determine its cause. Cryotherapy (the topical application of ice), massage, stretching and the use of nonsteroidal, anti-inflammatory drugs (NSAIDs), among other less conventional approaches, have been evaluated to determine if they can prevent or effectively treat delayed muscle soreness. To date, a therapy that consistently relieves delayed muscle soreness has yet to be identified. On the other hand, a few of the aforementioned therapies may have a mild positive impact if initiated immediately after intense or unusual exercise. Once an individual has experienced delayed muscle soreness at a specific exercise intensity, he or she shouldn't encounter that sensation again until the intensity level is increased. This is because delayed muscle soreness has been shown to produce a rapid adaptation response, which means that the muscles adapt to a given exercise intensity level. Until (or unless) the exercise intensity level is changed, soreness won't occur. This factor is the basis for the most widely recommended approach to preventing delayed muscle soreness: gradual progression and conservative increases in intensity, frequency and duration. Preliminary light exercise may prevent the onset of soreness following a heavy eccentric-exercise workout. Beginners should exercise with light weights, two to three times per week for one to two months, then gradually increase the intensity of their workouts. Conditioned exercisers who want to try a new workout or activity also should begin gradually, taking care not to be overzealous in how hard they exert themselves- particularly until their bodies adapt to the demands imposed upon them.