7.     Most people are good enough to start off in one of these high intensive programs but they need to understand them correctly, says physical therapist John Kaufman. 

8.     Most of them work is in a 10 to 20 second high interval where you can't do any more. 

9.     Your body's about fatigue followed by a rest period where it could be 30 seconds, it could be one minute.

10.     But the point is to go as hard as you can and then let your body have that time to rest.

11.     Back-to-back 25-minute classes are also popular at Legris Fitness Studio in Los Angeles. 

12.     Fit it out with the specially designed super performer inspired by classic Pilates performers all controlled by the instructors iPad.