Setup
Assume a quadruped position on hands at knees with band around stable leg just below the knee, band around moving leg just above the knee. Engage your core and find a neutral spine position.
Movement
Bring your moving leg back and up, straightening the leg as you do, stop when heel reaches the height of your hips, return to start
Tip
Pretend like the movement of the moving knee is an airplane going down the runway and then taking off
Do not excessively rotate or arch your back as you kick back and up, do not excessively round it as you return to the start position.