“The goal of a workout is to create micro trauma in the muscles,” explained Gutierrez. “As the muscle repairs itself, it becomes stronger and faster and has more endurance.”

Someone who is in serious training might even want to push it to the point of exhaustion, where your muscles shake and burn.

“But most of us shouldn’t get to that point,” Gutierrez said. “Most of the time you just want to feel that your muscles are engorged with blood, that you’ve increased the blood volume to them.”

In fact, Gutierrez said, it’s not during training that we get faster or stronger or more fit.

“You get stronger on your days off,” he said, adding you’ll notice the difference in your next workout when those 10 repetitions get easier.

So that’s the good kind of a pain. The pain that’s helping.

The bad kind of pain is “acute, sharp and sudden,” said Gutierrez, “and it doesn’t change or stays for 24 hours. That’s a sign of injury and that you should seek medical help.”

He cautioned that sometimes a hamstring or calf-muscle injury is put down to “tightness.” Be careful, the therapist warned.

“It could start as tightness, then a pull and then, all of a sudden, it will feel like someone shot you,” he said. “If you get those warning signs, back off.”

Gutierrez advised that if you still want to work out, change to “something that won’t get your heart rate up,” such as yoga or strength training.

“Most injuries are the result of too much, too soon,” he said.