Many, many bodily joints and tissues need to function well to be able to fully bend forward. Poor hamstrings, though … they always get blamed!
To regain forward bending ability, I hardly ever loosen patients’ hamstrings. However, say a patient did simply need looser hamstrings - then clinical care is hardly needed. (Stretching is not rocket science!) With consistent home stretching, hamstring length better consistently improve.
In almost all cases, forward bending is limited because lumbar structures are moving improperly. Usually it’s that the joints themselves are misaligned. In other cases, compressed/adhered/trapped nerves create nerve tension that limits this movement (with or without contemporary joint malalignment).
Forward bending (lumbar flexion) is usually restored once we get the patients’ lumbar structures moving properly again. Importantly, using forward bending to achieve this is beneficial in only a small group of patients. More commonly I utilize lumbar extension or sidegliding.
So why do people say they “feel it” in their hamstrings? It’s either that they’re actually feeling the sciatic nerve(s) pull or that, in attempting to bend further, their body eeeks out more motion in the only structures it can – muscles and tendons – so they “feel it” there. Expert mechanical clinicians know better. --Laura