By Stephanie Stahl

PHILADELPHIA (CBS) — New Year’s resolutions to exercise more and get in shape are popular. In January, memberships to fitness clubs always spike with people feeling motivated. One specialized type of class is especially catching on.

Doctors say getting regular exercise of any kind is important. And while walking is fine, more intense aerobic workouts can be good for you.

Many gyms are now offering treadmill running classes.

A treadmill-only class helps participants take their running to the next level.

“If we’re asking someone to push at a level two, it’s an endurance pace,” Stride Spin And Fitness co-owner Misa Dugally said. “Everybody has a different endurance pace.”

There are different versions of the running classes, where people can usually work at their own level, motivated by high energy, lights out and music blasting.

“Absolutely. Anybody can do it,” Dugally said.

Participants say the class makes running easier.

“The road is a hard surface and it took its toll on me,” runner Paul Casey said. “I had major knee surgery. I lost a large piece of cartilage after running two marathons in one year.”

The studio is called Stride Spin And Fitness and uses specialized treadmills that have a soft, curved surface.

“These individual rubber-slats that have all the shock-absorbing ability, very different than a belt on a treadmill,” Dugally said.

Unlike doing it on your own, in treadmill classes, a trainer is standing by to correct mistakes.

Running classes usually cost about $30 for an hour. They’re especially busy now with getting in shape and working out is on the top of many New Year’s resolutions.

The average person can burn over 550 calories jogging for an hour.

Stephanie Stahl