Delayed onset muscle soreness—the kind that leaves you wincing as you walk down the stairs after squat day—is pretty common after your first day of a new workout. But it’s not as likely to happen after the second day, thanks to a phenomenon known as the repeated bout effect.
Essentially, a soreness-inducing workout seems to give you some protection from additional soreness that lasts for a good while. (It fades over time, but research suggests some amount of protection can last for months.) If you’ve ever followed a friend to the gym and done their workout with them, you’ve seen this in action. You may be sore for a week, but since they do this same workout all the time, they barely feel a thing.
This also explains why you’re more sore at the beginning of an exercise program than once you’re a few weeks in. Sometimes people wonder if the program has stopped working, but you can still get stronger even if you’re not getting sore, and vice versa.
How to use the repeated bout effect to your advantage
If you’re starting a new exercise program, or doing a new type of workout for the first time in a while, don’t go all-out on your first day. A medium intensity workout will still trigger the repeated bout effect, allowing you to go harder on your second day, once you’ve activated that protection.
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If you already did a killer first day and now you’re in agony, the best thing to do is to head back to the gym, on schedule. Giving yourself an extra rest day is fine if you need it, but please don’t think you have to wait until the soreness is gone. Work through it, and the soreness will subside.
Now, what if you’ve been working out for a while, but you’re still sore all the time? Chances are, you haven’t been doing the same movements consistently. If you squat, bench, and deadlift every week, you’ll be protected against soreness for your squat, bench, and deadlift workouts. But if you like variety so much that you’re doing a different YouTube video or a different CrossFit class every day, you’re not giving your body a chance to get used to any particular exercise.
(Sleeping enough and eating enough are also helpful at getting through soreness, so if you’re sore and you’re constantly dieting and never getting to bed on time, it’s worth taking a look at those habits as well.)
Like many problems in fitness, the solution to soreness is consistency. I know it’s daunting to be lying in bed the day after your first workout thinking ugh, I have to go back? But if you do, it gets better. I promise.
