Start in the same position as the double-leg back body work, lying flat on the ground with both legs on your surface. Brace your core and flatten your back against the ground, keeping your arms relaxed at your sides.
Center your right foot on the surface and lift your left foot, extending your left leg up toward the ceiling.
Push into your right foot to lift your hips a few inches off the floor. Make sure your right hip is still under your knee, really driving your foot into the surface to activate your hamstrings. Continue squeezing your core and glutes and keep your hips square, facing the ceiling.
Squeeze your glutes and push your right foot down a little more to pulse your hips up one more inch.
Lower your hips one inch but keep them lifted off the ground, still holding your core firm.
Continue pulsing your hips up and down for 30 seconds with your right foot planted, then repeat with your left foot down for another 30 seconds. If this causes discomfort in your back or knees, do the pulses with your feet on the floor in a single-leg glute bridge instead.