The GoFit Power Tubes are a convenient way to obtain a total body workout; they take up very little space and can be taken anywhere. They are available in Light, Medium or Heavy resistance and are sold separately. By following our recommended workouts, you will achieve maximum results. The Power Tubes provide resistance training, which when used in conjunction with cardio training, provide maximum fitness results. They will train all of the major muscle groups, with the exception of the abdominal muscles. (We recommend using the Ab Wheel for abdominal workouts.) The most efficient way to train aerobically is jumping rope.