When is a hamstring strain not a hamstring strain?

We have always have found the quadratus femoris is one of, if not the, 1st hip muscle to become dysfunctional in hip pain patients. Perhaps it is due to it being the southern most stabilizer of the deep 6. Long known as an adductor, but also external rotator, we find it is employed eccentrically when the foot the planted and people rotate to the same side as weight bearing, or people take a “sudden stumble” while running. It often mimics an insertional hamstring strain with regards to location. We were happy to see it is getting some of the attention it deserves : )

http://www.anatomy-physiotherapy.com/articles/musculoskeletal/lower-extremity/hip/1528-function-of-the-quadratus-femoris-and-obturator-externus

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