You were so enthusiastic when you started the month. You signed up for every class that sounded fun: HIIT, bikram, and rowing in one week? Sure, what could go wrong? A lot, it turns out: There are over 600 muscles in the human body and suddenly it feels like all of them are sore at once. Is this a sign you probably started a little too hard too soon? Yep, sorry. Is it also the sign of a great workout? Maybe — maybe not. Here's what your sore muscles are really trying to tell you. The technical term for being so sore that you have to crawl around your apartment floor on your stomach for a day (definitely not speaking from experience here) is "delayed-onset muscle soreness," a.k.a. "DOMS." Although any new fitness routine is bound to leave you with some soreness, the key here is the "delayed-onset" part. Because, unlike pulling a muscle or simply feeling your arm get tired after too many bicep curls, you don't feel DOMS until a full day or two after your workout. (Your muscles can definitely feel fatigued right after the workout, but probably not can't-move sore — not yet, anyway.) One early theory about DOMS was that a buildup of lactic acid was the real culprit, but that line of thinking has been basically abandoned at this point. When you exercise, your body does break down glucose into lactic acid, but your muscles then use it as fuel — it's a good thing! Plus, any lactic acid that's built up during a workout dissipates within a few hours, not days. Instead, experts currently believe that the soreness is a result of "microtraumas" in your muscles. Essentially, when you're working out — especially if you're doing a new activity or working out at a significantly higher level of intensity than you're used to — you're damaging your muscles and the surrounding connective tissue. But the soreness isn't a direct result of that damage. Although the mechanism isn't totally understood, it looks like that pain is actually a side effect of the inflammatory muscle repair process, which is why you don't feel it immediately. Sure, "damage" doesn't sound like a great thing. But this isn't the same as a long-term injury. These are teeny tiny tears that heal quickly and can actually make your muscles stronger over time. However, that doesn't necessarily mean that you're building a ton of new muscle if you're sore (in other words, pain doesn't always equal gain). It's more like a sign that your muscles are adapting to this new activity. The good news is that your body adapts pretty quickly, meaning it's unlikely that you'll feel similarly sore if you ever make it back to another SoulCycle class. In fact, according to the American College of Sports Medicine, surviving one episode of extreme soreness may provide some protection against a subsequent one for a few weeks. So if you were thinking of calling quits on your new running routine, or, honestly, giving up physical activity altogether in favor of a more sea cucumber-like lifestyle, we don't blame you — but you really don't need to! Getting back into things with some light exercise is key, as is stretching post-workout and building a rest day or two into your weekly routine. From there, you can slowly build up the intensity of your workouts and make peace with the fact that you'll definitely feel sore again at some point. For now, though, there's not too much you can do to speed up DOMS recovery. Staying hydrated and eating a high-carb snack before working out are definitely good things to do, but they won't do much good for soreness, unfortunately. So get cozy with an ice pack and some ibuprofen if you really need it — and have no shame about crawling on the floor for the day.