The hamstring muscle group is one of the most commonly talked about structures when it comes to injuries and rehabilitation.

It is believed that a reduction in hamstring flexibility leads to decreased range of motion (ROM) of the knee and hip joint, which subsequently leads to a chain reaction up and down the body.

The most common tool used to improve hamstring flexibility is stretching. There are many types of stretching which include: static and Proprioceptive Neuromuscular Facilitation (PNF) type stretching. 

This study investigated the effectiveness of static vs. PNF stretching in improving hamstring flexibility.