HOW: Start by lying on your back with a band between your ankles. Keeping your core engaged, slowly lift both legs away from the floor by bending your knee and bringing your heel towards your hips. If you want to target the left hamstrings like in the video, keep your leg still. Slowly kick your right leg towards the ground. The closer you move your right leg away from your left leg, the harder the exercise will be. Do not let the left leg move!
FEEL: You shoulder feel your hamstring muscles behind your thigh working as kick your other leg towards the ground.
COMPENSATION: Do not arch your back. Keep your ribcage down and your core on. Do not let your working hamstring move!