Try this warm-up exercise.

1. Lie on your stomach with your feet straight, hands resting in front of the body.
2. Tense one glute and slowly lift the leg, keeping it straight and keeping the hip down. Raise only a few inches.
3. Pause at the top, then slowly lower the leg so the thigh touches the ground but the foot does not; repeat.
4. This can be done as a warm up or exercise; perform 1-3 sets of 12-15 repetitions.

For a more advanced movement:
1. Lie on your back with one foot bent 45 degrees and the other straight.
2. Push off the ball of the foot and thrust both hips upward while raising the opposite thigh. Stop when the legs are parallel to the rising hip. Keep the abs tight and squeeze the hamstring.
3. Lower the hips to the ground and repeat.

Source: Noam Tamir, TS Fitness