The first-ever scientific study of its kind was conducted recently on the popular PX90 weight loss and fitness program by the American Council on Exercise (ACE) with the help of the University of Wisconsin’s La Crosse program. The study was led by John Porcari, Ph.D. and Joel Woldy, M.S., who are both researchers with the University’s Exercise and Health Program and aimed to determine the true energy cost and exercise intensity of the PX90 program.
The concept of “muscle confusion” is at the heart of the PX90 program, which was created by trainer Tony Horton. In more scientific terms, this is known as “daily undulating periodization,” which is a fancy way of saying that you are changing up workouts so often that the body does not have time to adapt and become used to the exercise. Since this means the body is always operating at sub-optimal efficiency, it will burn more fat and build muscle more quickly. Although very popular among participants, until now PX90 had never been studied scientifically, leaving only anecdotal evidence regarding its effectiveness.
PX90 has sold more than 3 million copies by November of last year, with numbers undoubtedly reaching well beyond that as we approach 2012. Stars like Sheryl Crow, Billy Idol and Bruce Springsteen have backed the program, which bills itself as “The Ultimate 90-Day Home Fitness Bootcamp.”
For the study, researchers recruited 16 athletes, choosing healthy subjects between the ages of 19 and 26 who exercise regularly and had previous experience with either PX90 or a comparable circuit-style weight training and aerobic program. First, they established a baseline of fitness by performing tests to determine the maximum heart rate and VO2max for all subjects. Next, the participants were asked to complete up to three practice sessions of each of the PX90 workouts the study examined, which included Cardio X, Chest, Shoulders & Triceps, Legs & Back and Plyometrics.
After the subjects had become familiar with the workouts, testing began. Participants were asked to participate to the best of their abilities through all phases of the testing process, while researchers monitored their heart rates, perceived exertion (RPE) and the predicted VO2 that was exerted during the session.
“The basis of muscle confusion is to keep the body from becoming too efficient at performing individual and sets of exercises,” said Alice Burron, MS Exercise Physiology, ACE National Spokesperson and ACE Personal Trainer. “This type of inefficiency burns more calories because the muscles haven’t yet adapted to the new workload. Overall, more calories are burned, and as a percentage, then, more calories are burned from fat. That is if a proper caloric intake is maintained in tandem with the workout.”
The study results are clear, with male subjects burning between 441 and 699 kcals per workout and female subjects burning between 302 and 544 kcals per workout. These results prove that PX90 is an effective weight loss and fitness tool that researchers believe “meets or exceeds established fitness industry standards for losing weight and improving cardiorespiratory fitness.”
Sources: American Council On Exercise, SELF Magazine
