Single Leg RDL

Target Muscles: 
Hamstring
Lower Back
Calves
Ankles
Proper Technique: 

Balance weight onto a single leg while maintaining a slight bend in the knee. Bend the torso forward and kick the leg not used for support backward while keeping both as straight as possible. As the body and extended leg become parallel with the ground, reach downward to touch the ankle or toes if possible. Stand back up to a normal stance and step forward to perform the reach again while supported on the opposite leg. Movement occurs in the sagittal plane.

Improper Technique: 

Allowing excessive curvature of the back or attempting to touch the toes in a very rapid manner. This stretch should be performed at controlled pace. Furthermore, attempt to keep the leg that is extended behind the body as straight as possible.

Positions: 
Balance weight onto a single leg while maintaining a slight bend in the knee.
Bend the torso forward, kick the other leg backward; maintain back straight
Common Errors: 

Failure to maintain a slight bend in the knee in the supporting leg, or keeping the leg extended behind the body straight.

Video: