Don't have anything organized to post right now. The off-season, for many of our teams here, is in full effect, so life is pretty busy to say the least. So I am pulling this from my notebook where I jot down notes and ideas. Sorry if it is scattered...
Some notes I've made on some of possibilities as to why the hamstrings can become strained. Something I've dealt with personally on numerous occasions. It amazes me the simplistic approach people still take with these nagging injuries... the hamstrings are not necessarily weak! And leg curls and "you need to stretch more" are not the answer!
-The quad-to-hamstring ratio is a bunch of bull.
-The hamstrings are almost always NOT weak, just overworked. They now not only the flex the knee, extend the hip (overworked here), eccentrically control the knee, but also are being looked to for stability at the hip.
-Need to check if the glutes work (synergistic muscle), however we need to take it steps further than this because it is always much deeper. Sometimes the glutes are active, just in an inefficient position to help.
-Question needs to be asked: Why don't the glutes fire; why are the hip flexors tight, short, and/or overactive or even tight, short, and underactive?
-Check motor patterns (what are the athlete's habitual patterns; this is the key).
-Could be and most often is, poor stability and motor control in the lumbar spine.
-Jammed joints, arthrokinetic reflex inhibition of muscles, capsular adhesions.
-Poor thoracic mobility/extension with over-activity of upper trapezius, levator scapulae, scalenes; this creates faulty head position which often times affects eye position. (this all helps to create an extensor reflex, throwing off the mechanics of proper sprint pattern.
-Ankle mobility/motor control. Foot strike position which can be caused and usually is, by lumbopelvic positioning and rhythm.
-Internal vs. external rotation balance in the hip. A good balance is need between the two, but lack of controlled internal rotation will not allow the glute to get a pre-stretch to allow it to concentrically produce force. This is how quality movement is made; muscles need a pre-stretch to work efficiently.
-Quality hip internal rotation consists of adequate hip abductor activation and again, lumbar stability.
-Lumbar instability is usually greater on the same side as the affected limb (Functional Movment Screen rotary stability test).
-Contralateral rotation of the torso from affected limb (arises from habitual patterns).
-Motor skill as it relates to stride mechanics: chasing or pulling center of gravity when at absolute speed.
-Athletes with chronic pulls need continual reinforcement of efficient motor patterns, "cueing" exercises, along with soft-tissue work to release some of the fascial restrictions that have been built up over time.
-Foot strike patterns; striking the ground with the midfoot as opposed to the forefoot and rearfoot. Midfoot striking creates efficiency in running/sprinting. Allows for elasticity, reducing the need for concentric work. Is it because of an ankle issue or is it because of bad lumbopelvic positioning?
And these are just of few of the possible reasons.