Lie on the ground with a TRX at your feet. Lift both your feet into the straps, making sure they are secure. Tighten your core and place your hands at your sides. Drive your hips up while maintaining a straight line with your body. Curl your feet in, moving them towards your glutes. Maintain balance with your hands on the ground. Once your feet reach your glutes, slowly extend your feet back to the starting position. Do not allow your hips to drop. Keep your core braced throughout the movement.