Muscle Soreness

Last Editorial Review: 1/12/2007

Author: Richard Weil, MEd, CDE
Medical Editor: Jay W. Marks, MD

For some individuals, sore muscles are a reward after a hard workout. In fact, some people aren't happy unless they're sore after their workout, while others could live without it. Either way, all of us have probably experienced muscle soreness at one time or another. In this article, I'll review the causes, treatment, and prevention of muscle soreness.

What Causes Muscle Soreness?

One of the consequences of vigorous exercise—heavy weight lifting, a tough day of speed work on the track, or the stairclimber at the gym—is an accumulation of lactic acid in the muscles. Lactic acid is a normal byproduct of muscle metabolism, but it can irritate muscles and cause discomfort and soreness. Muscle soreness associated with exercise is known as delayed onset muscle soreness or DOMS. DOMS can make it difficult to walk, reduce your strength, or make your life uncomfortable for a couple of days.

But lactic acid isn't the only culprit in DOMS. In fact, lactic acid is removed from muscle anywhere from just a few hours to less than a day after a workout, and so it doesn't explain the soreness experienced days after a workout. What is it then that causes DOMS for days after exercise? The answer is swelling in the muscle compartment that results from an influx of white blood cells, prostaglandins (which are antiinflammatory), and other nutrients and fluids that flow to the muscles to repair the "damage" after a tough workout. The type of muscle damage I am referring to is microscopic (it occurs in small protein contractile units of the muscle called myofibrils) and is part of the normal process of growth in the body called anabolism. It is not the type of damage or injury that you see your doctor about. The swelling and inflammation can build up for days after a workout, and that's why muscle soreness may be worse two, three, or even four days after a workout (it can take up to five days for muscles to heal completely depending on the intensity of the workout).

In 1983, in one of the first studies of the causes of DOMS, subjects ran level or downhill on a treadmill (downhill running causes more muscle damage than level running due to eccentric muscle contractions), and then afterward, subjects' perception of soreness, lactic acid levels, and muscle swelling was measured. Results showed approximately equal levels of lactic acid in both groups, but greater swelling in the downhill runners, and only downhill runners reported soreness. Since only the downhill runners were sore and the only difference between the level- and downhill-runners was the swelling, the investigators concluded that it was the swelling that caused the delayed onset muscle soreness and not the lactic acid, a finding consistent with the idea that lactic acid clears the muscle soon after exercise and is not responsible for DOMS.

Is Soreness a Prerequisite for Growth?

I'm occasionally asked if soreness after a workout is necessary to get results. Although there's no evidence to support this idea and individuals certainly get stronger even if they don't get sore, some people just aren't satisfied with their workout unless they're sore, and there may be some rationale for this logic. Remember, there must be microscopic damage to muscle fibers before there can be growth, so if you're sore, it means there was damage and thus growth must not be far behind. But again, there's no evidence that soreness is necessary for growth, and until we understand more about the process, it's probably enough to say that soreness could be a potential marker or predictor of how much growth there will be. In the meantime, I've included three tips for increasing muscle growth, and increasing the likelihood of soreness for those of you who crave it.

1. Increase the weight so that you lift reps in the six to 10 range to fatigue, and then once a week lift heavier, in the one to six range.

2. Try slow, eccentric contractions. Eccentric contractions are the lowering portion of the lift (sometimes called the negative contraction), and as I mentioned above, these contractions make you sorer than the concentric contractions (the lifting, or positive, portion of the exercise). To emphasize eccentric contractions, complete your set to failure, then either "cheat up" the weight or have your spotter assist with extra reps (assisted negatives), and then lower each rep slowly on your own (five to 10 seconds). For example, if you're doing a standing biceps curl, complete the set to fatigue, cheat the weight up or have your spotter assist, and then lower it slowly on your own to the starting position.

3. Try forced negatives. Forced negatives are where you complete a set to failure, and then your spotter helps you lift another rep and then pushes back down on the weight while you resist. This is an effective but very demanding technique!

Treating and Preventing DOMS

Do Antiinflammatories Work?

In a 1993 study of the effect of an over-the-counter antiinflammatory (ibuprofen) on DOMS, researchers compared subjects given ibuprofen four hours before weight lifting (pre-lifting group) to subjects given ibuprofen 24 hours after lifting. Results showed that the pre-lifting ibuprofen group reported 40% to 50% less soreness than the after-lifting group, proving in this study that ibuprofen taken before exercise reduced soreness more than taking it after. A limitation of this study was the lack of a control group of subjects who did not take ibuprofen after working out to compare with subjects who did to see if ibuprofen helps at all after exercise. To answer this question, a study in 2003 investigated subjects who took ibuprofen or sham (placebo) every eight hours for 48 hours after they lifted weights. The ibuprofen group reported less soreness than the sham group, proving that ibuprofen worked when taken after exercise.

From these studies, it appears as if some people will respond to taking antiinflammatories before working out, and others will respond when they take it afterward. How hard you lift, how long you rest, and your level of activity when not working out will factor in to the equation as well.

Does Pre-Stretching Help?

In an interesting study conducted in 1999, subjects were asked to stretch only one of their legs and then perform leg exercises with both legs. Subjects reported afterward that both legs had equal amounts of soreness for at least 48 hours, proving in this study that pre-exercise stretching did not help prevent DOMS. These results, and findings from other similar studies, lead to the conclusion that stretching before exercise does not help prevent DOMS. An intriguing question is what effect stretching after a workout has on DOMS, but I am not aware of any studies that have investigated this. However, I do believe that stretching, and physical activity in general, can help alleviate soreness and offer some suggestions about it at the end of the article.

Does Massage Help?

Massage does help reduce DOMS and a number of studies prove it. In two similarly designed studies where all subjects lifted weights but only half received massages two hours after working out, subjects who received massages reported less muscle soreness than the subjects who did not. In a longer-term study in 2005 in which soreness and swelling were measured, all subjects lifted weights, but only half of them received massages 30 minutes after exercise and then one, two, three, four, seven, 10, and 14 days post-exercise. The subjects who received massages reported 30% less soreness than subjects who were not massaged, and importantly, swelling in the muscle was reduced only in the subjects who received massage. It may be that the pressure of the massage strokes moved fluid out of the muscle and reduced the swelling that causes DOMS. Whatever the mechanism of action, massage after a workout (sometimes lots of it) was effective in reducing DOMS in these studies.


Pictures of the 7 Most Effective Exercises to Do at the Gym or Home (and Tips to Improve Form) See Slideshow

Should You Work Out When You're Sore?

Some studies show that neither aerobic nor resistance exercise helps alleviate soreness. My experience is different. I have observed an alleviation of symptoms in sore individuals if they start their workout with light aerobic (cardio) exercise for 10-15 minutes followed up with stretching. In many of these cases, individuals can go on to do their full cardio and/or resistance exercise workout without a problem. This effect may be similar to the massage effect in that the light cardio and stretching help reduce swelling, perhaps by increasing circulation to and from the muscle.

If you want to work out when you're sore, then I suggest starting with 10-15 minutes of light cardio followed by stretching, then lifting, and/or more cardio. If the soreness resolves or doesn't interfere with your performance, then continue with the workout. But if the soreness worsens or causes too much pain for the workout to be worthwhile (you can only 50% of what you normally do), then you're probably better off either working another muscle group, or taking the day off, because muscles grow during downtime, not when you train, and if your muscles get sorer during your workout, then you need more time to rest, recover, and grow.

In summary, ibuprofen taken before or after a workout, and massage afterward (sometimes a lot of massage), can reduce DOMS, but stretching before a workout doesn't seem to help. Although there is no evidence that stretching after exercise reduces DOMS, I have seen light cardio for eight to 10 minutes followed by stretching reduce DOMS. Everyone responds differently, and so I encourage you to experiment with different routines until you find one that works for you. I also recommend that you speak with your doctor before taking any medication, over-the-counter or prescription, and that includes ibuprofen.

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