Step 2: The TRX straps are set to a few inches off the floor. Hold onto each handle and keep them close into your body before beginning this movement.
Step 3: Begin this movement by raising your arms forward. Synchronize the movement by bringing your hip forward.
Step 4: Continue extending your arms and lowering your hips until your arms are extended above your head, in a straight line with your body, and your hips are fully extended. Basically, your body is now in a straight line from your wrists to your knees.
Step 5: From the fully extended position, begin to get yourself back up to the starting position by pressing downward with your extended arms. Maintain the straight line of your body from your head to your knees by keeping your core engaged, and your glutes tight.
Step 6: Repeat this movement several times.
How to progress the exercise
The progression of this exercise is all about levers. The shorter the lever (as in the knees to chest), the easier the movement is. If you perform the exercise with your legs straight (ie: pike), the challenge is much greater.
Mastery of a strong plank is needed for this exercise, especially to avoid sagging at the hipe when performing the exercise very dynamically. The abdominal muscles need to be firing quite strongly to avoid overusing the hip flexors in the knee to chest movement.