The mild muscle strain injury creates microscopic damage to the muscle fibers. Scientists believe this damage, coupled with the inflammation that accompanies these tears, causes the pain.

“The aches and pains should be minor,” says Carol Torgan, an exercise physiologist and fellow of the American College of Sports Medicine, “and are simply indications that muscles are adapting to your fitness regimen.”

No one is immune to muscle soreness. Exercise neophytes and body builders alike experience delayed onset muscle soreness.

“Anyone can get cramps or DOMS, from weekend warriors to elite athletes,” says Torgan. “The muscle discomfort is simply a symptom of using your muscles and placing stresses on them that are leading to adaptations to make them stronger and better able to perform the task the next time.”

But for the deconditioned person starting out, this can be intimidating. People starting an exercise program need guidance, Torgan says.

“The big problem is with people that aren’t very fit and go out and try these things; they get all excited to start a new class and the instructors don’t tell them that they might get sore,” she says.

“To them they might feel very sore, and because they aren’t familiar with it, they might worry that they’ve hurt themselves. Then they won’t want to do it again.”

Letting them know it’s OK to be sore may help them work through that first few days without being discouraged.