P90X founder Tony Horton puts himself through the workout, which was found… (Jay L. Clendenin / Los Angeles…)
The P90X workout is an incredibly popular home-based, boot camp-style video exercise program that some fitness fanatics swear by. But does it do the job? A study of the system finds it does improve cardio respiratory function.
The study was commissioned by the American Council on Exercise and done by researchers at the departments of exercise and sport science and physical therapy at the University of Wisconsin-La Crosse. The findings were not published in a peer-review journal, and the experts have also looked at the effectiveness of Reebok toning shoes and shoes that simulate barefoot running.
In this study, 16 healthy, fit test subjects age 19 to 26 were put through four workouts, including warm-up, conditioning and cool-down phases, They did as many repetitions as they could and used comfortable weights. Data were then analyzed on the participants' heart rates and VO2max levels, a measure of maximum oxygen consumption.
For men, average heart rates ranged from 67% to 83% of their maximums, and for women the range was 65% to 88% of their maximums. Men burned 441 calories to 699 calories per workout, while women burned 302 to 544 calories per workout. Doing plyometric exercises burned the most calories, while the chest, shoulders and triceps workout burned the least.
That means, according to the researchers, that the workout met or surpassed recognized fitness industry standards for dropping weight and improving cardio respiratory fitness.
P90X is based on the concept of periodization, or periodically changing up a training program so that the body doesn't get used to the workouts and continues to get stronger and more fit.
"Our study results found P90X offers an effective workout, and, when combined with a sensible eating plan, we believe it can help many individuals achieve their weight-loss and fitness goals in the comfort of their homes," said Cedric X. Bryant, ACE's chief science officer.