Good point. Multi joint muscle groups like the hamstrings behave uniquely. During the descent of the squat the hip flexes and knee flexes which could suggest that their is not significant change in length in the hamstrings. Keep in mind however there is more than just muscle at play. The hamstrings are a more effective knee flexor than hip extensor so as the knee flexes, portions of the hamstring are shortening while more proximal portions are “lengthening”. Now is this more of the fascial components that reach up into the sacrotuberous ligament and sacrum? I am not sure. It may just be a superficial view that during hip flexion, the hip extensors change in length, but we could also look at the biceps femoris long head which does not flex the knee. This portion of the hamstring does not flex the knee but does extend the hip and eccentrically decelerates femoral internal rotation, particularly during hip flexion. It does lengthen in the sagital plane on the descent of the squat. It should allow some internal rotation of the femur as well as the hip flexes. Maybe I should have been more specific? A great conversation piece Fabian:)

Eric

Sorry for the long delay in my response. I feel that full range of motion dips for anyone is unhealthy for the anterior capsule of the shoulder and upper cervical region. However, for advanced users such as yourself who have the awareness to maintain a safe range of motion, there can absolutely be a benefit. Thanks for the post!

Eric

when doing a squat, the hamstrings are not really lenghtened, aren’t they?
they just change their relative position to the femur under activity.

Or am I wrong?

Perhaps it’s a matter, much like with other exercises, of awareness of one’s position and doing the exercise correctly.