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Why Are My Muscles Sore After a Workout?

Not Sure Why Your Muscles Are So Sore? We've Got Everything You Need to Know

Muscle Soreness

If you work out — and you, kind reader, most definitely do — you're probably familiar with soreness the day or two after said workout. But, not just any exercise can result in that tenderness and intense soreness you feel. What you're experiencing is called delayed onset muscle soreness (DOMS), and it's typically onset by hard workouts where you, perhaps, increased your reps or performed moves you've never done before.

Paul Searles, CSCS, from the New York Sports Science Lab (along with others we've interviewed in the past), told POPSUGAR that what causes DOMS isn't scientifically proven, but it's widely thought that it's a result of microtears in the muscle fibers, which then leads to gradual inflammation.

Workouts that focus on eccentric portions of exercises — movements where you're lowering your body under control and lengthening the muscles — as opposed to isometric (fixed position) and concentric (shortening) movements typically lead to these microtears, Searles said. Eccentric movements would be, for example, lowering your body into a squat or deadlift or, as Searles mentioned, a negative pull-up. Also, "the more total reps in a workout, the more microtrauma in the muscles, and therefore more soreness after," he explained.

How to Treat Sore Muscles

DOMS can last for days or even a week depending on the intensity of your workout and, in all actuality, it's not something you can cure. There are things you can do, though, to help with the discomfort, and a lot of these remedies can be found at home (see a full list here). Ahead are a few options you have for treating DOMS:

DOMS is manageable, and you can also read up on expert-approved tips for how to treat sore leg, back, and chest muscles specifically. Here's more good news: soreness can absolutely mean muscle gain! Sander Rubin, MD, sports medicine specialist at Northwestern Medicine, told POPSUGAR in a previous interview that inflammation is required for muscles to get bigger and stronger. As part of that response, your body sends out pain signals, which can cause that feeling of soreness. However, DOMS isn't necessarily required for growth, Dr. Rubin said. "The lack of soreness does not mean your workout wasn't successful in building muscle."

Prevention and Warning Signs to Remember

You can try to prevent DOMS by gradually easing into workouts, Tedd Keating, PhD, associate professor of kinesiology at Manhattan College, told POPSUGAR in a previous interview. "Remember, big changes are one of the causes [of DOMS]. Be especially cautious when adding or turning up exercises with a strong eccentric component," he said — aka, be mindful of how many squats, deadlifts, etc. you're doing. Mix it up!

Make sure you're also mindful of the amount of pain you're in, especially if it radiates down your legs or gets worse instead of better, as well as any muscle atrophy or profound weakness you feel, and contact your doctor accordingly. Rhabdomyolysis, the rapid breakdown of skeletal muscle tissue, can be indicated by cola-colored urine and is another reason to seek medical attention because, if left untreated, it could lead to kidney failure. For more of our articles on all things DOMS, check out our handy DOMS page.

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