EVERY time I do my sprints, I end up pulling a hamstring. In HS I never pulled a hamstring. Besides warm up, why is this happening? I may never be able to do sprints without pulling a hamstring.
Your Hammies are prolly not strong enough. Lack of flexibility could also be a cause. go train em. but take care not to do too much. Since traumatizing them only makes them shorter and weaker. Try Good mornings / snatch grip deadlifts / reeverse hypers / good ole SQ and Deads / stay off the leg curls !!!
Sounds like you’ve got an imbalance going between quads and hams. If the hams aren’t at least 66% as strong as the quads, you’re susceptible to pulls. Prioritize those suckers. Maybe throw in a hamstring specialization day, or at least work them first on leg day.
With respect to jerom, indeed use leg curls. As both he and TC mentioned they are probably weak in relation to the rest of your legs (especially the quads). The reason for using both leg curls and hip extensor movements in working the hamstrings is that the hamstrings are involved in hip extension (in movements such as dead lifts, good mornings, romanian dead lifts, and to an extent squats), and knee flexion movements (such as leg curls). However, there are really only two good ways to effectively overload the knee flexion function and that is to either sprint (hence your cramping) or do leg curls. Try TC’s hamstring first workout from issue 29, also not too long ago Charles posted three movements in Poetry in Motion, that all worked the hamstrings well. Also, flexibility is key when training the lower body, and the hamstrings are the muscles that most people lack flexibility in.
I want to defend my statement of no leg curls. Try this:
Westside barbell style sled dragging. attach a weight to your belt and walk forward. mimics sprinting pretty well but with controlled movements. Of course it is hard to prepare for sprinting cause the stretch shortening puts stresses on your hams not easily done voluntarily in training.
I would agree with the need to train both aspects of knee function, if the desire is for maximal leg size. However, the hamstring does not really flex the knee in sprinting, the fact that it pulls to an acute angle is more of a function of momentum, combined with the movement of the knee forward. To summarize, knee curls will help you gain hamstring size, but will not do a whole lot in gain sprint speed/function.
If possible, dragging the sled would be an excellent way to work the hams, as this would overload both hamstring functions, as does sprinting. The pull in sprinting isn’t just momentum unless your pretty slow or have awful form. In fact, the pull (i.e., knee flexion) comes when the ball of the foot strikes the track as the knee flexion gives the hip extension function of the ham string and glute a leverage advantage. That is why many sprinters utilize the plyometric exercise “butt kicks” in their routine. Now, after stating how important it is to work both functions, i would say that for optimal speed and power that the hip extension function of the hams is the most important.