WACO, TX — The fitness levels of participants and their intensity of exercise determine the number of calories burned in a Curves workout, according to a Baylor University study.

The fittest study participants burned up to 522 calories during the 30-minute workout. The least fit women in the study burned between 164 and 238 calories in 30 minutes. The women worked at 80 percent of their maximal heart rate and 64 percent of their maximal oxygen uptake, which is below their anaerobic threshold, so they couldn't have burned any more calories in 30 minutes with Curves or any other workout, said Dr. Richard Kreider, professor and director of Baylor's Exercise and Sports Nutrition Lab, which has studied Curves since 2002.