Is stiffness not a bad thing?
It depends on the definition of stiffness and most on this panel would advocate elasticity over stiffness.
Results from a study by Kubo (2000) indicate that the elasticity of the tendon structures of both the VL and MG are similar between both sprinters and untrained persons. Fukashiro (2002) agreed somewhat in that black and white athletes had similar tendon elasticity (assuming that black athletes are superior runners- LOL) suggesting that elasticity is not related to faster running. Interestingly black athletes have much greater muscle stiffness which should be detrimental to high velocity tasks.
I’m exploring the theory that muscle pre-activity in preparation for landing increases tendon stiffness or more likely muscle-tendon reactivity. The tendon is crimped under no tension and early contraction of muscle (and shortening thereof) reduces the slackness of the tendon thereby increasing the rate at which force can be produced against the ground upon contact. However the timing of such contraction is critical and must be skillfully tuned.
Your thoughts on stiffness/elasticity?