There's growing support for what's known as high intensity interval training. You literally pack a weeks' worth of exercise into a short amount of time.
At CrossFit Chicago, the workout is intense and rapid.
Across town, another slower intense workout is taking place at PhysioLife Studios.
The approaches are different but the underlying principal is the same. If you push the body really hard for a short time you can get the same results as in a traditional workout. You are basically squeezing in an entire week's worth of exercise into one hour.
Sound too good to be true? But the research is mounting and some exercise experts are creating a buzz with claims this could revolutionize exercise.
"They showed that when you make people do very short very hard exercise the changes that the people make are very similar to exercises over a longer period of time," said Jonathan Dugas, Ph.D., exercise physiologist, Univ. of Illinois at Chicago.
The research focuses specifically on high intensity interval training. It's recommended you spend about four minutes at 100 percent capacity and then rest for several minutes in between. The entire work out lasts 20 to 30 minutes once or twice a week.
Research shows interval training can double endurance, improve oxygen use and strength by 10 percent and speed by at least 5 percent.
So why isn't everyone doing this?
"There's still lots of unanswered question before we can take this out of the box that it's in and apply it to everyone," said Dugas.
Dugas says it's not for everyone. But if it gets people up and off the couch and generally interested in exercising, he's all for it.
"We're trying to get each muscle group to failure or exhaustion in a specified window of time," said Estelle Harford, personal trainer, PhysioLife Studios. "So we focus on quality vs. quantity."
At PhysioLife, it's high intensity strength training on specialized equipment. It involves slowly lifting the weights and slowly releasing until muscles reach fatigue. The promise is a total body workout in 30 minutes just two times a week.
The theory is the body builds more muscle, it increases your metabolism and burns more calories even at rest.
"I get better results than when I was in the gym for an hour and a half a day, five days a week," said Rob Semrad.
Back at CrossFit Chicago, there's a lot of sweating and panting as participants rotate quickly between weight lifting, rowing, and more, all in a matter of minutes.
"You're going to make a lot more gains with what we do at once or twice a week," said Rudy Tapalla, owner, CrossFit Chicago.
Terry Levin, 53, does an explosive workout right along with her 16-year-old son. "It's the most incredible workout, mind, body and soul. It's amazing," said Levin.
Most of the research has been done in young, physically fit people. But some studies are showing older people even those with some medical conditions might be able to handle it. Experts say much more research is needed. And most importantly, talk to your doctor first before beginning any new workout.
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