The stuff below is the the guidelines from Sports medicine Australia. A moderate hamstring injury is a 4-8 week time line
Hamstring Injuries
Grade Description
1 (mild)
Overstretching without tearing of muscle or tendon fibres.
Symptoms may not present until activity is over.
Usually no loss of muscular strength or flexibility.
Increased tightness in the muscle during stretch or through a full range of motion.
A feeling of pain may be reported with sitting or while walking uphill or ascending stairs.
Depending on the severity, weight bearing activities may or may not be possible, walking properly may be possible and there will be minimal swelling.
2 (moderate)
Partial tear in the muscle.
Muscular strength and flexibility is reduced.
Pain is more immediate and more severe than the pain of a Grade 1 strain.
Pain on stretch and contraction of the muscle, and is usually sore to touch.
Limping is likely during walking, and occasional sudden twinges of pain during activity may occur.
Bending the knee against resistance will cause pain and there may be some difficulty in fully straightening the knee.
3 (severe)
Severe or complete rupture of the muscle. May be a large lump (of muscle tissue) above a depression where the tear is.
Sudden, sharp pain in the back of the thigh.
Walking is not possible without pain.
After a few days with Grade 2 and 3 injuries, a large bruise may appear below the injury site caused by bleeding within the tissues.
May require surgical repair.
Timeframes for rehabilitation and return to sport vary depending on the nature and severity of the strain. As a general rule, Grade 1 hamstring strains should be rested from sporting activity for about three weeks and Grade 2 injuries for a minimum of four to eight weeks. In the case of a complete rupture (Grade 3 strain), the muscle may have to be repaired surgically and the rehabilitation to follow will take about three months.
