The question: I find that I’m sorer two days after a tough workout than I was the day after. What’s up with that?
The experts: Jordan Metzl, M.D., an exercise physician and author of The Exercise Cure; Greg Justice, an exercise physiologist and author of Mind Over Fatter.
The answer: This common and super annoying occurrence is a result of delayed onset muscle soreness (DOMS), which generates inflammation in your muscles after a really tough workout—especially if you haven’t worked out in a while, says Metzl. Though your workout is to blame for the inflammation, a healing process called the inflammatory response cascade is what’s really causing your pain 48 hours after your sweat session, he says.
The response is a series of events that happens during a period of four to five days, says Metzl. On day one, your body responds to the injured area by releasing hormones called cytokines. These hormones direct cells to go heal your inflamed muscles. At the same time, prostaglandins, hormones that also affect how cells respond to injury, send blood to the area to heal it. This migration of cells to your tired muscles starts out slowly during the 24 hours after your workout—the healing process hasn’t kicked into high gear yet. However, on dreaded day two, the flood of cells to the area of inflammation, a.k.a. your muscles, reaches it’s peak and continues the healing response, he says. This means you’re going to struggle getting out of bed.
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If you’ve heard that lactic acid might have something to do with soreness, here’s the deal on that: “We used to think that lactic acid was to blame for DOMS before we understood cellular biology as much,†says Metzl. Now it’s clear that lactic acid only affects short-term exercise tolerance—or how long you can endure a tough workout—and isn’t a factor in DOMS.
Although any type of tough workout can cause DOMS, eccentric muscle training—which is when you lengthen your muscles while contracting them, like during the downward part of a bicep curl—could create the most. That’s because your workout causes micro-trauma, or tiny tears in your muscle fibers, which your body needs to repair to build muscle, says Justice. Eccentric training causes more micro-tears in your muscles than other kinds of training, he says.
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So here’s the good part of your I-can’t-move feeling: It means that you did “a lot of great work and are in the process of building stronger muscles,†says Metzl. To ease the pain and help your muscles recover, keep yourself moving by doing active recovery exercises like biking, yoga, and foam roller moves. Nixing movement altogether can lead to more soreness, he says.
The pain should start to get better after day two or three. If it’s not lessening or if you start to have discolored urine, you should talk to your doctor. It’s possible that you could have rhabdomyolysis, which is basically DOMS gone wild, says Metzl, and is a serious and dangerous condition.
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