Step 1: Lie on your back with your heels in the TRX foot cradles; legs are extended, and the TRX straps are set to about a foot above the ground.
Step 2: From here, proceed to pull your heels towards your buttocks.
Step 3: Press through your heel to lift the hips up. Essentially you are performing a bridge movement. Lift your hips to a maximum where your hips are in line with your knees and shoulders in a straight line. The shoulder blades remain in contact with the floor, and your arms are by your side pressing into the floor to help stabilize your torso. As you are lifting your hips, squeeze your glutes and pull in your abdominals to avoid overusing the lower back muscles.
Step 4: Proceed to lower your hips down as you extend your legs out, both in a controlled manner.
Step 5: repeat the movement several times.
How to progress the exercise
Progressing this exercise from holding onto both TRX handles to holding only one of the handles, creates more challenge to this movement. If you start with holding the handle that is opposite to the squatting leg, you may feel more stable than if you held onto the handle on the same side as your squatting leg. Incorporate a BOSU or balance disc under your foot for more difficulty
Care must be taken in order to avoid compensating in this exercise. If your hips, knees, and ankles are not aligned in a straight line throughout the movement, too much force can be placed on the hips or knees, resulting in joint problems. So, Quality over quantity is important here.