Starting Position: Place your feet securely in the foot cradles positioned directly under the TRX anchor point. Apply downward pressure with your heels by dorsiflexing your ankles (toes point towards your shins) Gently lie back on a mat / floor with your arms at your sides and palms flat on the ground. Contract your core and glute muscles to lift your hips off the mat / floor keeping your body aligned and rigid, using your hands to help stabilize your body. Slowly contract your hamstrings to move your heels towards your hips while keeping your ankles in dorsiflexion. The hips should move into flexion (bending in the hips), but your torso should remain rigid with your weight bearing on your shoulders. Keep you feet together throughout the exercise.
Upward Phase: Exhale and press your hips towards the ceiling, extending your hips into a rigid straight line, but avoid arching your lower back. Avoid any back and forth swinging of the TRX straps.
Downward Phase: Inhale and slowly return your hips to your starting position. Avoid any back and forth swinging of the TRX straps.
Progression: 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.