Power 90 Extreme -- more commonly known as P90X -- is an intense 90-day workout program designed by celebrity fitness instructor Tony Horton. The program consists of intense daily exercises covering both cardio work and resistance training. The P90X doubles schedule is a particularly intense schedule for the program that adds additional cardio workouts to help you lose weight and increase your cardiovascular fitness.
The P90X program comes with three different scheduling options to fit your needs: classic, lean and doubles. The classic schedule is balanced with 50 percent of the workouts being cardio and the other half being resistance training. In the lean schedule the number of resistance workouts is reduced and the number of cardio exercises is increased. The doubles schedule follows the P90X classic schedule but adds more cardio workouts on top of it.
The purpose of the P90X doubles schedule is to increase your calorie burn, thereby helping you to shed more fat than with the classic schedule. It's the schedule of choice for the person who wants to focus primarily on weight loss in the P90X program. The doubles schedule can also be used by athletes and casual exercisers who want to increase their cardiovascular fitness.
Like all P90X schedules, the doubles schedule has three phases. Phase one lasts four weeks with one workout per day: three cardio workouts, three resistance workouts and an optional stretch workout on the seventh day of each week. In phase two, which lasts another four weeks, you'll add three additional cardio workouts to your routine, so you're doing a double set of workouts three times a week. In phase three you'll be doing four additional cardio workouts per week.
P90X is an intense program and the doubles schedule is the most intense way of doing it. The P90X fitness guide warns that you should be injury-free and have plenty of energy before starting the program under this schedule. The guide suggests that you skip the extra workout if your feeling excessively tired, noting there are no benefits to over-training. If the P90X doubles schedule is too intense, consider using the classic or lean schedules which have just one workout per day.