The American Council on Exercise (ACE) has released the results of a study that looked at the effectiveness of the P90X. The 90-day, interval boot camp-style home exercise program was identified by ACE as one of the top fitness trends to watch in 2012.

The study, conducted by a team of experts from the Departments of Exercise and Sport Science and Physical Therapy at the University of Wisconsin-LaCrosse, found the program meets or exceeds the recognized standards for improving cardio-respiratory fitness. A group of 16 subjects ranging in age from 19 to 26 participated in the study, which was designed to determine the true exercise intensity and calories burned when using the P90X program.

The group completed up to three practice sessions of each of the four workouts chosen for the study, which included legs and back, Plyometrics, Cardio X and chest, shoulders and triceps. The actual testing began after each participant became proficient in the workouts, and they exercised to the best of their abilities throughout the warm-up, conditioning phase and cool-down while researchers recorded the subjects’ heart rate at one-minute intervals. At the end of each workout, ratings of perceived exertion (RPE) were recorded, while the heart-rate data was used to determine the subjects’ predicted maximal oxygen consumption and caloric expenditure. The participants were given 48 hours of recovery rest between each workout test.

Results showed that female subjects demonstrated slightly higher numbers of heart rate maximum and maximal oxygen consumption than the male subjects, and the percentages for both groups registered well within the range to provide a high-intensity dose of exercise. The tests also found the male subjects burned an estimated 441 to 699 kcals per workout, while females burned a total of 302 to 544 kcals per workout.

“The American Council on Exercise tests programs like P90X as part of our mission to help empower the American public with the information and tools needed to live a fit and healthy lifestyle,” ACE’s chief science officer, Cedric X. Bryant, said in a statement. “High-intensity, interval-style home exercise programs can be a time-efficient workout for many individuals—particularly those with a baseline level of fitness.”