Why Post-Workout Muscle Soreness Hits People at Different Times
As fitness editors, we here at Shape go to a lot of workouts together. If we hit one before work Monday, the question on Tuesday is always, “I’m pretty sore today. Are you?” My answer is almost always no—until Wednesday when I’m groaning every time I stand up. (Which is when it’s time to break out these 6 Ways to Relieve Sore Muscles After Overtraining.)
In fact, this happens so often—part of the staff is always sore 24 hours later, while the rest of us don’t feel it for two or three days—that the standard response around the office is now, “No, I’m a two-day-sore person.”
Here’s the thing: That’s not an actually accurate statement, I’ve learned.
What Causes Soreness?
Muscle soreness isn’t a reflection of your individual physiological nuances, says Chris Jordan, a certified strength and conditioning specialist and the director of exercise physiology at the Johnson & Johnson Human Performance Institute. It’s much more complicated than that.
It’s important to understand what muscle soreness comes from. “When you work out, you’re damaging your muscles on a cellular level. Once you tear tissue, there’s an inflammatory response, which means swelling, pain, and soreness,” he explains. There are four main factors that impact how much damage is being done—and therefore how sore you will be: (Here are 8 Solutions for Your Worst Workout Woes.)
1. Exercise intensity: The harder you work, the greater the likelihood of microtrauma on the cells of your muscle. Both lifting heavy weights and explosive-but-short sprinting—both too much, too soon—can cause your body to overdo it, Jordan explains.
2.Exercise duration: A comfortable, low-speed jog may be low intensity, but if you’re used to three miles and decide to tackle 15, the prolonged and unfamiliar duration that your muscles are expected to work for will cause similar microtrauma.
3.Exercise type: There are two types of motion: concentric training and eccentric training. With the first, muscle fibers are shortening—like the up of a bicep curl—and in the latter, they’re lengthening—like the down of a curl. Because your muscle fibers are lengthening under tension, though, eccentric tension is more likely to cause soreness. That means anytime you do an explosive up and slow, steady down, or when you run uphill, your chances of sore muscles go up.
4. Fitness level: If you’ve been out of the gym and just hit it hard, it’s fairly obvious you’re going to be sore. You’re asking a lot of your unconditioned body, Jordan says. But the same goes for trying a new workout. Almost every activity—from running to spinning to barre—uses completely different muscle groups. And working unconditioned muscles (oh hello, abs!) can shock your system.
What Timeline Are We Talking?
If you’re hitting your regular workout for the usual length of time, you may be a little sore hours later or the next day, but this is usually not enough to complain about. Plus, stretching properly can help (in fact, that’s one of 3 Things You Need to Do Immediately After a Workout).
If you’re new to a workout though, you’re going to experience what researchers call delayed onset muscle soreness (DOMS)—a much more intense pain that usually peaks 24 to 48 hours after you shock your body, says Elaine Choung-Hee Lee, Ph.D., an assistant professor of kinesiology at the University of Connecticut.
Why does it take at least a day to set in? “Once the muscle is damaged, the repair process begins, but it takes a little bit of time for the cells to actually get to where they need to be, to make the proper proteins, and then to actually begin the repair,” Lee says. So when my fellow editors are sore 24 hours later, but my aches don’t hit for another day or two, the reason is pretty simple: Either we did a workout they’re used to and I’m not, or I’m just way less fit than they are. (Can we all just agree it’s the first reason?)
This is why recovery matters: Lifting heavy weights and doing damage is good and crucial to building muscle. But if you do harm to the same muscles, say, three days in a row, you’re compounding the initial damage. This not only makes it take longer for your muscles to heal, but it can actually impair your ability to build that bulk. “To build more muscle, you have to get rid of the damaged tissue and other molecules that are released upon trauma—you have to clean up before you can rebuild,” Lee explains. “If there’s long-term damage that isn’t given sufficient time to recover and repair, your body focuses on that instead of on building your muscles back bigger and stronger.”
So How Do You Need to Adjust?
Most of us not only schedule our workouts for the entire week, but also do so following the old mentality of one day rest in between a muscle group—arms Monday/Wednesday, legs Tuesday/Thursday. But this means that if we try a new class and experience DOMS, we’re left to power through any soreness we’re still feeling.
You should actually be adjusting your workouts to how sore you are, Jordan says. “As long as you let that damage heal and recover fully, you’ll come out of it stronger and more resilient,” he says. So if you’re planning for a workout you haven’t done in two weeks, schedule to rest that muscle group for a full 72 hours instead of just 48 before you hit it hard again, he advises. You can still workout, just not the same muscles at the same level of intensity. (Too Sore to Exercise? Do This Active Recovery Workout.)
And while we know it’s hard to take an extra day off, if you let yourself recover fully, you’ll probably find the next time you hit that super intense boxing class, you won’t be nearly as sore after, he adds.
In the bigger picture, that’s definitely worth it.