If you exercise, especially if you lift weights, you have probably heard the adage, “No pain, no gain.” This may serve as motivation for some people, but the belief that exercise results in pain might be a good reason not to work out for others. If you are one of those people, you should know that idea that exercise should hurt is simply wrong—muscle pain during or following exercise usually suggests an injury. However, some muscle soreness is unavoidable, especially if you are new to exercise.
This soreness is called DOMS—delayed onset muscle soreness—and it typically occurs 24 to 48 hours after exercise. It can range from a mild reminder that you worked out to more severe soreness, weakness, and tenderness. DOMS can occur after any type of exercise, but is more common following weight training, especially if it is your first session or a particularly intense workout.
A common belief is that lactic acid build-up in the muscle causes muscle soreness. This is based on the fact that during intense exercise like weight training the muscles make energy for contraction anaerobically (without oxygen), which leads to lactic acid production. This is in contrast to aerobic exercises like walking or jogging that produce energy using oxygen, with little lactic acid build-up. This belief that lactic acid causes DOMS has been shown to be false since any lactic acid that is produced during exercise is cleared shortly after you finish, long before muscle soreness begins. This is one of several commonly held myths about exercise that just won’t go away.
So what causes DOMS? It turns out that strenuous exercise leads to microscopic tears in the muscle, which leads to inflammation and soreness. This sounds bad, but the muscle damage is an important step in the muscle getting bigger and stronger. Your muscles are made up of protein filaments that shorten, leading to a contraction. When you lift weights your muscles respond by creating more protein filaments, allowing you to generate more force and causing the muscle to grow in size, called hypertrophy. The mechanism that leads to creating more muscle protein is stimulated by the damage that occurs during exercise. Without that stimulus, muscle growth wouldn’t occur. This is why weight training programs call for increasing the resistance over time to overload the muscle. Without increasing the weight, you wouldn’t get much stronger.
While the muscle adaptations that are associated with DOMS are beneficial, you may wish to avoid or limit the soreness aspect. You can do this by beginning your exercise program slowly. Resist the temptation to do too much too soon! Build up your time and intensity slowly over several weeks and start weight training with lighter weights. Remember, your goal is to begin an exercise program that you will sustain. Many people have quit working out because they started off with exercise that was too intense. While your goal should be to exercise every day, there is nothing wrong with taking a day off between workouts early on.
If you do experience DOMS you should rest those muscles until the soreness subsides. You can also try an over-the-counter pain reliever or applying ice to the sore muscles. If the soreness isn’t too severe, you can still exercise, but keep the intensity low. Weight training sessions should be scheduled a few days apart to allow for muscle recovery, but aerobic exercise can usually be done every day. If your arms are sore from lifting weights, you can always go for a walk!