Starting Position: Place your feet securely into the foot cradles positioned directly under the anchor point. Apply downward pressure with the tops of your feet by plantarflexing your ankles (toes point away from your shins). Gently lie flat on your stomach with your hands placed shoulder-width apart, under your shoulders and facing forward. Stiffen your torso by contracting your core/abdominal muscles ("bracing"), and your glutes and quadriceps (butt and thigh muscles).
Upward Phase: Exhale and slowly press yourself upward until your elbows are fully extended, aligning your head and spine (avoid any sagging or aching in your low back or hips hiking upwards). Keep your feet together throughout the exercise and avoid any back and forth swinging of the TRX straps.
Downward Phase: Maintaining your rigid torso, inhale and slowly lower your body towards the floor, touching your chin or upper chest to the floor. Again, avoid any arching or sagging in your low back.
Exercise Variation: The intensity of this exercise can be increased by lengthening the straps and positioning your body further away from under the anchor point of the TRX.