What causes loss of motion after a muscle strain? I can’t seem to get full knee motion after a hamstring injury.

Studies show muscles can heal but it’s a slow process with a high rate of re-injury. The
formation of scar tissue seems to slow up the recovery process of injured muscle.

Fibrous scar tissue forms when the body sends too much growth factor to the injured
muscle. Some growth factor is needed to stimulate new cell growth. These new cells fill
in the damaged area.

Too much of the growth factor TGF-beta leads to too much fibrosis. Fibrous scar tissue
prevents full recovery of the injured muscle resulting in a loss of motion. Physical
therapy can help in some cases. The use of deep heat, friction massage, and stretching
may help restore flexibility. A program if resistance training can help restore full
strength.