Why Muscles Get Sore

While some people think of having sore muscles after a workout as an accomplishment and an indication of hard work, others see it as a deterrent from future workouts. Whatever your view of sore muscles is, if you exercise regularly it is important for you to understand why your muscles get sore, and whether the soreness indicates a good workout or something to be concerned about.
The period of 24-48 hours after a workout is when muscle soreness peaks. This muscle soreness is known as delayed onset muscle soreness, or DOMS. This soreness may also be accompanied by a reduction in range of motion and flexibility. Typically, after 48 hours the soreness will subside. The cause of DOMS is believed to be tiny tears in the muscle fibers caused by the contraction of muscles during exercise. The severity of the soreness depends on how challenging the exercise is, how long the exercise session is, if there was a significant change in the type of exercises done in a routine, and how accustomed to exercise a person is. A person who exercises vigorously on a regular basis will experience less severe DOMS than someone who is new to exercise.
DOMS is most prevalent in resistance training exercise, such as weight training, body weight exercises, or using resistance bands. DOMS is part of the process where muscles adapt to activity and become stronger and better able to perform the same exercise next time. It is also possible to experience DOMS after cardiovascular exercise.
If you are new to exercise try not to let DOMS dissuade you from future workouts. Once your body becomes accustomed to exercise DOMS should be less prevalent. You may also be able to reduce the severity of DOMS by properly warming up before working out, and cooling down, and stretching after working out.
People sometimes wonder whether or not they should exercise again if they are experiencing DOMS. My answer is that if a particular muscle group still hurts, resistance training exercises should not be performed for it. This doesn't mean you can't exercise. If the muscles of the chest are sore you could focus your workout on your back muscles, perhaps. Also, if you are experiencing DOMS cardiovascular exercise may be a good option, as long as it does not cause more pain.
While DOMS is typically a normal and healthy reaction to exercise, there are times when DOMS may be an indication of too much stress on the body. DOMS does not necessarily indicate a good workout. If you still feel significant soreness 72 hours after your workout you may want to consider reducing the intensity of your next workout and gradually build back up. More pain from DOMS does not necessarily mean more progress. In the long run your progress will be better is you gradually build up, rather than pushing yourself too hard at once. This can lead to burn out, and even injuries.
DOMS is a part of physical fitness that you shouldn't let prevent you from regular exercise. It can provide us with some feedback by letting us know that we did something the body isn't used to, or possibly that we took a workout too far. Listen to your body, let it rest and recover from workouts, gradually increase the intensity of your workouts, and your progress will be remarkable.