The study monitored 15 healthy women aged 25 to 56 through two Curves workouts. It concluded that each circuit training session burned an average of 184 calories. The most calories burned by a study participant was 233, the low 150. A 30-minute hatha yoga session burns around 80 calories, moderate spin cycling about 225.

The Curves burn is equivalent to walking 30 minutes at about 3.5 miles per hour on a flat treadmill and meets the government minimum recommendation of 30 minutes of moderate-intensity exercise most days. (People trying to lose or keep off lost weight should exercise 60 to 90 minutes most days.)

Curves gyms are no-frills, women-only facilities with 12 hydraulic resistance machines and springy recovery boards between stations. Most women do a 25-minute session comprising two full circuits of resistance training interspersed with walking or jogging on the boards, followed by five minutes of stretching. Curves clones offer similar workouts.

Researcher John Porcari, an exercise and sport science professor at the University of Wisconsin-La Crosse, said most study participants reached a level of exertion slightly above the minimum threshold for improving aerobic capacity. Heart rates hit a high average of 75 percent of age-adjusted maximum, within guidelines for a moderate-intensity workout.

So: Is Curves enough?

"I'd rather see people alternate Curves with higher-intensity cardio, like brisk walking, two to three days a week," Porcari said. "That's proven to be better for lowering cholesterol, improving circulation and a lot of other benefits." But he said Curves offers a better full-body workout than walking.

ACE's chief exercise physiologist, Cedric X. Bryant, said healthy women with no current or past weight issues seeking to maintain baseline fitness could stick with Curves for years. "But if you're looking for weight loss or improved [athletic] performance, you will want to do more than just the Curves workout."

Bryant and Porcari said intensity is key. "With hydraulic machines your exertion is proportional to your effort," Bryant said. "You could just go through the motions without using too much energy."

Curves International issued a statement saying it is "pleased that an independent body has tested our program and found that it does indeed provide the health benefits" of aerobic exercise and strength training.

Source:Curves