Hamstring strains are a common injury in the athletic population, especially in sports that require fast running including track, football, and soccer. You may feel or observe: •A sudden pop in the back of your thigh •Cramping or burning in the hamstring •Soreness in the back of the thigh •Bruising a few hours after your injury •Pain with sitting on a hard surface •Difficulty straightening your knee or bending your hip •Difficulty walking This type of injury can occur due to several factors including: •Decreased hip flexibility •Improper warm up before activity •Hamstring weakness •Older age •Muscle fatigue The severity of hamstring strain is usually classified into 3 categories: •Grade 1 strains involve overstretching the hamstring muscle. Minimal damage is seen in the muscle and it feels more like muscle cramping or a “pulled muscle.” Recovery usually takes 2-6 weeks. •Grade 2 strains involve some muscle fiber tearing. In addition to feeling a pulled muscle, you may also feel burning in the area and notice slight bruising. Recovery can take up to 8-10 weeks. •Grade 3 strains involves tearing of many fibers or a complete tear in the hamstring muscle. This type of injury is accompanied with significant bruising and you may see a lump of tissue in the back of the thigh. Recovery can take 3 months or longer and, in some cases, you may require surgery. In any category of hamstring injury, physical therapy is usually the first option. Your therapist will focus on restoring your knee and hip mobility, instruct on strengthening exercises to the muscles surrounding your hip and knee, and review pain free hamstring strengthening exercises. They may discuss injury prevention techniques including a strengthening regimen during in-season activities and proper warm-up before your sport.