Effects of prior hamstring injuries

Previous hamstring injury is associated with altered biceps femoris associated muscle activity and potentially injurious kinematics.

“Previously injured athletes demonstrated significantly reduced biceps femoris muscle activation ratios with respect to ipsilateral gluteus maximus, ipsilateral erector spinae, ipsilateral external oblique, and contralateral rectus femoris in the late swing phase. We also detected sagittal asymmetry in hip flexion, pelvic tilt, and medial rotation of the knee effectively putting the hamstrings in a lengthened position just before heel strike." 

The biomechanics of running in athletes with previous hamstring injury: A case-control study. C. Daly¹, U. McCarthy Persson², R. Twycross-Lewis¹, R. C. Woledge^1,† andD. Morrissey^1,
http://onlinelibrary.wiley.com/d…/10.1111/sms.12464/abstract