The Curves workout seems to be a good "moderate intensity" routine, using about 184 calories in a 30-minute session, according to a recent study.
Considered the fastest growing franchise in U.S. history, Curves has more than 8,500 locations worldwide and over 4 million women have joined since it opened in the early 1990s. The plain-Jane studios consist of resistance equipment with springy recovery boards between each station and usually attract sedentary, middle-aged women who are intimidated by larger coed workout facilities.
Curves has never made any results claims about its 30-minute workouts which includes a 25-minute circuit on 12 hydraulic resistance machines, alternating between 30 seconds of lifting and 30 seconds of walking on a springy recovery board, ending with five minutes of stretching.
So that's why the American Council on Exercise stepped in: ACE funded an independent study to determine the intensity of the pre-set Curves workout as well as how many calories are used during a typical routine.
The study and its results
Conducted by researchers from the University of Wisconsin, La Crosse, the study followed 15 women, between the ages of 26 and 55 (42 was the average age), during a workout. Before doing the Curves workout, they were pre-tested to determine their aerobic endurance, oxygen consumption, perceived exertion and calories burned. Afterward, the women worked out at two Curves gyms in Wisconsin with regular members. The only stipulation placed on them was to refrain from talking, a common occurrence among Curves members.
Researchers Kristin Greany, M.S., R.D., and John Porcari, Ph.D., found the 25-minute circuit alone burned a mean of 163 calories and the five-minute stretching session afterward used another 21 calories (range among the subjects was 152 to 233 calories). "Intensity-wise, it's similar to walking 4 mph (for 30 minutes) on a flat treadmill, so it's a moderate-intensity workout," said researcher Greany, in a report issued by ACE. She added that it is a total-body workout because there is resistance training for the upper body and core, as well as the legs.
The study also found that participants' rating of perceived exertion on the resistance machines was much higher than on walking/jogging boards -- 14 versus 12.6 for the boards on a scale of 6 to 20; however, there were no differences in any objective measure between the two.
Porcari said overall the results were very positive. Participants were at 75 percent of the heart-rate maximum, within recommended guidelines and above the minimum threshold for improving aerobic capacity.
For a beginning, previously inactive exerciser -- with caveats
Overall, Greany and Porcari said the Curves workout is an ideal low- to moderate-intensity exercise program for a sedentary non-exerciser, rather than a very active exerciser.
They did, however, identify a few potential pitfalls of the Curves workout:
>> The hydraulic resistance machines used in the circuit workout are not adjustable, so the machines may not perfectly fit some individuals causing them to sacrifice proper form.
>> They noted some of the women were more focused on chatting during their workouts than exercising, diminishing the routine's benefits, and suggested exercisers should avoid turning the workout session into a social hour.
>> Although franchise owners go through training at Curves headquarters, day-to-day staff does not and would benefit from additional training.
The complete study, with full results and comparison charts, is in the March/April issue of the ACE Fitness Matters magazine, at www.acefitness.org/getfit/curves.cfm.