Cardio Intervals vs. Cardio X

Cardio Intervals

Interval training, in the words of the Mayo Clinic, "is simply alternating bursts of intense activity with intervals of lighter activity." Effectively, it involves alternating between periods of higher and lower intensity cardio. For instance, you might alternate between sprint cycling and casually cycling or between running at full speed and jogging. According to the Mayo Clinic, interval training burns more calories than steady state cardio due to the spikes in your intensity level. Interval training can also improve your cardiovascular fitness because you're increasing your aerobic capacity, enabling you to exercise longer or with more intensity.

"Cardio X"

"Cardio X" is one of the workouts from the P90X workout series. It's not a form of interval training, but a type of steady state cardio. It combines elements from the other cardio workouts in P90X to create an all new workout. These elements include bits of yoga, kenpo karate and plyometrics, or jump training. According to the "P90X Fitness Guide" the "Cardio X" routine keeps your heart rate below the anaerobic threshold, which prevents muscle fiber from breaking down.

"P90X One on One Cardio Intervals"

One video of cardio intervals is included in the P90X One on One series. This series, which is designed for P90X grads, simply features Tony Horton demonstrating the workout by himself without any of the demonstrators featured in P90X. The workout incorporates elements of plyometrics and kenpo karate, arranged into intervals. This means you will alternate between doing the exercises at a high intensity and low intensity to maximize your calorie burn.

"Power 90 Master Series Cardio Intervals"

The other version of cardio intervals is part of the Power 90 Master Series. The Power 90 Master Series is a bridge program for people who have completed Power 90 and who want to graduate to P90X. Like the video of cardio intervals from the One on One series, this version also incorporates elements of plyometrics and kenpo karate arranged into high and low intensity intervals. The difference between this program and the One on One version is that the intensity is lower because it's intended for people who are building up to P90X.

Schedules

Each of the programs is used in different ways. "Cardio X" isn't used in all the P90X schedules. It's only used if you follow the "doubles" schedule. The doubles schedule is a more intense program with extra cardio workouts. If you follow this schedule, "Cardio X" is added on as a second workout for some of the days. "Power 90 Master Series Cardio Intervals" is used throughout the Power 90 Master Series. "P90X One on One Cardio Intervals" is different from the other programs because it doesn't follow a set schedule. It's intended to be used as you see fit as part of your own workout plan.