I understand that it is the eccentric contractions that cause Delayed onset muscle soreness. So why is that the day after sprint training my hamstrings feel like hell. In my humble opinion it seems that the only resisted part of the stride where the hamstrings are concerned is the concentric contraction.
Am I wrong is the resisted part the eccentric contraction too or is it that concentric contractions can cause DOMS but to a lesser degree.
It is not actually true that eccentric contractions cause DOMS, it is thought that DOMS results from the inflammatory response that is typically associated with eccentric contraction.
That being said, during a sprint the hamstring will be subjected to eccentric contractions. As you stride forward, the hamstring is lengthening. As you make the transition from striding forward to the power stroke the hams may be eccentrically contracting. As the leg is fully extended, the hamstring may also be on the descending limb of the length tension curve making it more susceptible to injury or microtrauma. Therefore you may be inducing the eccentric contraction induced muscle injury which leads to DOMS.
There are other factors though that could lead to the DOMS phenomenon other than the purely biomechanical though. The high calcium transients associated with high metabolic states can stimulate calcium dependent proteases. It is also possible that the metabolites of the muscular activity could serve to attract neutrophils to the area and this would ultmately lead to DOMS. I suspect though, since the DOMS is isolated in the hams, that the biomechanical contribution is the primary component.