Step 2: Begin the first movement (push up) by engaging your shoulder girdle stability with your scapulae depressed; You are still maintaining a strong plank position with your core and glutes tight.
Step 3: From here, proceed to lower your body towards the floor by bending your arms. Your shoulders continue to remain stable. Keep your elbow in towards your sides at around 45 degrees to keep the Serratus Anterior activated, which will help for shoulder stability.
Step 4: Push yourself back up to the original plank position.
Step 5: The second movement (knees to chest) requires shifting your weight forward so your shoulders are in front of your hands; at the same time, proceed to bring your knees into your chest, focusing on engaging the abdominal’s (not the hip flexors).
Step 6: Return back to the starting plank position, ready to perform the push up again.
Step 7: Repeat the alternating Push-Up/ Knees to Chest movement.
How to progress the exercise
Firstly, placing the foot of the leg that is not set in the TRX foot cradle onto the floor will take some of the challenges away from this exercise. Secondly, changing the angle of the exercise by shortening the TRX straps, will inherently place you closer and closer to an upside down vertical position (ie: inverted), thereby increasing the load on the shoulders.
The further you get into an inverted position, the more of a multidirectional challenge there is to your core, Conversely, a position closer to horizontal can still be challenging to the core, though more unidirectional (ie: not letting your back droop or hips sag towards the floor).