Muscle soreness: how long it lasts, and whether to train through it

The workout felt fine. The next morning the stairs feel different, and the day after that it's worse. That's delayed-onset muscle soreness, usually shortened to DOMS: a dull, aching pain in the muscle, felt mostly when you press on it, contract it or stretch it.¹

This page covers what brings it on, how long it usually lasts, whether to work out when you're sore, why it fades as you keep training, and what it does and doesn't tell you about a workout. It's about training decisions, not remedies; whether a cool-down or stretching afterward helps is on the cool-down page. Where rest days go in your week is on rest days.

What brings it on

Three things, mostly:

• Something new. A review of the research on DOMS found it most common when athletes return to training after a period of reduced activity, and also common whenever they're first introduced to a kind of activity.² A new exercise, a new program and the first session back all count.
• The lowering half of a lift. Eccentric actions, where the muscle lengthens under load,¹ cause small-scale muscle damage more often and more severely than other muscle actions.² That's the way down in a squat or a Romanian deadlift, and the slow lowering of a negative when you're learning a pull-up.
• How hard and how long. The intensity and duration of the exercise matter too.²

Exactly why it hurts isn't settled. The same review counted up to six proposed explanations, from muscle damage to inflammation, and concluded that two or more of them probably work together.² A 2019 review of eccentric exercise adds that why the soreness arrives with a delay is still not clearly understood.¹

How long muscle soreness lasts

The timing is what puts "delayed" in the name. The 2019 review describes the usual course after exercise your muscles aren't used to:¹

So the second day is often worse than the first, and that's the usual pattern. Two more things the reviews say about those days:

• Sore muscles are weaker for a while. Soreness can reduce your range of motion and the peak force a muscle produces,² and athletes with DOMS are often unable to train at their maximal intensity.¹
• The soreness can leave before the strength comes back. Muscle function can stay down for a while after the soreness has gone.¹ Feeling fine isn't always the same as being back to full strength.

Should you work out when you're sore?

Mostly yes, with adjustments, though the evidence comes from young men in lab studies and from advice written for athletes. The research gives three pieces of the answer:

• Training sore muscles didn't add damage in a lab study. Of 22 college-age men, 12 repeated a hard eccentric arm exercise on the six days after a first damaging session. Training the already-damaged muscles did not make the damage or inflammation worse.³
• Hard efforts can wait. The 2019 review advises against high-intensity exercise, particularly explosive efforts, while the muscle is still recovering.¹
• Go lighter, or train something else. The DOMS review advises athletes who must train daily to cut the intensity and length of their sessions for a day or two after a session that left them very sore, or to train the body parts that are less affected.²

Put together, a day that starts sore usually looks like one of these:

1. A little stiff, but moving normally. Train as planned. If the first work set moves badly, take some weight off for the day.
2. Very sore in the muscles you planned to train. Train the other muscles today, which a workout split makes easy, or do the planned session lighter and shorter. Save heavy attempts and jumps for a day or two later.
3. So sore it changes how you move. That's one of the signs to take an extra rest day.
4. It hurts in a sharp or unusual way. That isn't soreness. Read the last section before you train again.

Why the second time hurts less

The first hard session of a new movement buys you something. Researchers call it the repeated-bout effect: a single bout of eccentric exercise leaves the muscle less damaged by the bouts that follow. How it works isn't fully explained yet.⁴ What changes the next time is clearer: less soreness, less swelling, and a faster return of strength and range of motion.¹

• Light sessions build it too. In a study of 30 untrained men, four light eccentric arm sessions at 40% of maximal strength, two weeks apart, reduced the damage from a later all-out session as well as one all-out session did. Each light session also caused smaller changes than an all-out first bout.⁵ That's the case for easing in, and it fits the advice to introduce new or eccentric exercises gradually over a week or two.²
• It lasts months, not forever. In 35 male students who repeated a bout of eccentric arm exercise, the effect for most measures lasted at least six months, with less soreness at six months, and was lost between nine and twelve.⁶ So after a long break, the soreness of a first session can come back. How to restart without overdoing it is on getting back into training.

What soreness doesn't tell you

Soreness is common, but it's a poor scorecard. Here's what the research says about three ideas attached to it:

• "Sore means it was a good workout." How sore you get is a poor gauge of how much the muscle was damaged. In 110 male students who did 12, 24 or 60 maximal eccentric arm reps, the bigger sessions caused larger drops in strength, more swelling and a slower recovery, yet soreness when the muscle was pressed or flexed was no different from the smallest session; only soreness on stretching was lower after it. The authors call DOMS a poor reflector of muscle damage.⁷
• "No soreness, no growth." In an eight-week study of eccentric cycling, one group first eased in over three weeks, before the eight weeks began, so their muscles showed no detectable damage, while the other started with a damaging session and reported more soreness early on. With the same total work, the two groups gained the same muscle size, and strength rose 25% and 26%.⁸ Getting less sore as the weeks go on is the repeated-bout effect, not a sign the training stopped working.
• "It's lactic acid." In a 1983 study, 45 minutes of level treadmill running raised blood lactic acid but brought no significant soreness afterward. Downhill running never raised it, yet brought significant soreness. The authors concluded that lactic acid is not related to DOMS.⁹

The limits are worth knowing too. Most of the studies above tested men doing hard lowering reps with one arm muscle in a lab, which is not the same as a full-body session in a gym. And people vary widely in how they respond to eccentric exercise.¹ The timeline above is the usual course, not a promise for every muscle and every person.

When it isn't soreness

If you'd rather not plan around it alone

Knowing that soreness peaks a day or two later is easy. Building a week where a sore Thursday doesn't wreck Friday is the part a page can't do for you. Coaching is the version where your workouts live in the Trainerize app, built around the days you actually have, and a weekly call looks at the week you just had and rebuilds the next one. Coaching to build muscle explains how that works, and here's how to apply. Otherwise: the next time you add a new exercise, start it light, and let the second session be the harder one.