I have a confession: I don't mind exercise-related pain. In fact, I welcome it. Now before you conclude that I'm a masochist, let me explain: The type of pain I'm talking about is soreness that comes after exercise and may last for a few days before going away. Known as delayed onset muscle soreness, or DOMS for short, it's a sign that your workout is making you stronger. I consider it "good" pain. That's in contrast to "bad" pain, which typically happens during exercise and gets worse afterward. It's a sign that you have an injury.
Any type of activity can cause DOMS, especially if the exercise is strenuous or something to which your body isn't accustomed. However, DOMS is most likely to occur after muscle-lengthening (or eccentric) movements such as lowering a dumbbell or running downhill.
For nearly a century, DOMS was widely attributed to the buildup of lactic acid in muscles. Today, lactic acid retains its reputation among some in the fitness world as a pain-causing waste product. But science has shown that to be a bum rap. Our muscles break down glucose into lactic acid (technically lactate), which is used as fuel. Lactate is removed from muscle within a few hours after exercise, so lactic acid can't explain soreness that occurs a day or two later.
Instead, researchers now believe that the discomfort is due to the process by which the body repairs micro-tears in muscle caused by exercise. Soreness isn't the only symptom; swelling, stiffness, tenderness and a reduction in strength and range of motion can also occur. When you do the same activity again, your DOMS will likely be milder -- or won't occur at all. And you'll be stronger.
It's generally fine to exercise with DOMS, though you may need to dial back the intensity or focus on areas not affected. Taking a day off to rest is OK, but don't use DOMS as an excuse for an extended (or permanent) break from exercise.
In fact, physical activity may decrease your soreness, at least while you're doing the activity. Other methods may provide some relief as well. Here's the lowdown on three of them.
Heat and cold
In a review of 17 trials of ice-bath treatments, which are often used by athletes, researchers concluded that the technique may reduce soreness after exercise. But sitting in a tub of water chilled to 50-something degrees Fahrenheit -- ideally for 10 to 15 minutes, according to research -- isn't exactly pleasant.
A relatively new method is whole-body cryotherapy, in which you sit or stand for two to four minutes in a special chamber where the temperature is as low as minus 300 degrees Fahrenheit. (No, that's not a typo.) A review of four studies found that there's insufficient evidence to tell whether whole-body cryotherapy reduces DOMS. And potential risks, which include frostbite, oxygen deficiency and asphyxiation, have yet to be studied.
The conventional wisdom, with little direct evidence to support it, has been that cold is superior to heat in reducing DOMS. To test this idea, researchers did a randomized, head-to-head comparison. One hundred young adults performed squats for 15 minutes and then received one of four therapies: 1) cold wraps immediately after exercise; 2) cold wraps 24 hours after exercise; 3) heat wraps immediately after exercise; 4) heat wraps 24 hours after exercise. A fifth group, which served as a control, received no treatment.