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 pointing your toes. Lie flat on your stomach with your hands placed shoulder-width apart, under your shoulders and fingers facing forward. Brace your torso by engaging your core/abdominal muscles. Keep the glutes (butt) and quadriceps (thigh) muscles engaged and strong.
Exhale and slowly press your body off the floor until your elbows are straight (plank position) Keep your head and spine aligned. Do not allow the low back or ribcage sag or arch. Do not allow the hips to hike upward. Keep the glutes and quadriceps contracted to maintain hip stability. Your feet should be together throughout the exercise and avoid any back and forth swinging of the TRX straps.
Upward Phase: On an exhale, engage your abdominals. Bring your hips toward the ceiling and pull your legs toward your chest. Keep the legs straight and strong and toes pointed. Your feet should be glued together throughout the exercise. Continue the movement until your hips move directly over your shoulders in somewhat of a handstand position. Keep the torso rigid. Do not allow the spine to arch or bow.
Downward Phase: Inhale and slowly lower your body back to a plank position. Keep the torso rigid and head and spine aligned. Do not allow the low back or ribcage to sag.
Exercise Variation: The intensity of this exercise can be increased by lengthening the straps and positioning your body further away from the anchor point of the TRX.
Using the TRX certainly enhances the appeal of many exercises; however, trainers and individuals should not participate in these advanced exercises until they can demonstrate capability to effectively stabilize their lumber spine (low back) with their core muscles.