Use of Platelet Rich Plasma in the Management of Acute Hamstring Muscle Strain Injury

The purpose of this study is to evaluate the therapeutic benefit of utilizing complex growth factor preparations (Platelet Rich Plasma (PRP) in the management of acute hamstring injuries. The hypothesis is that the time to return to sport is shorter in the patient group treated with Complex Growth Factor Preparations (PRP) in combination with exercise therapy in comparison with 2 control groups: * the patient group treated with Platelet Poor Plasma (PPP) injections in combination with exercise therapy (control injection AND usual care). * the patient group treated with exercise therapy (usual care)