[b]Length Tension Curve.[/b]
At shortened lengths： active contraction dominates force generation.
Just beyond its resting length： passive tension begins to contribute and active tension is compromised.
At more elongated lengths： passive tension accounts for most of the total force.
The graph is s perfect depiction of why passive tension is not a significant contributor at top speed running. At maximal speeds, the force production times approach the limit of human muscle contraction time so there is barely enough time to achieve peak tension in the whole muscle. When the muscle does activate it is better to have considerable overlap of cross bridges which implies that operating at the extreme ranges of joint movement would penalise force production. Stiffness at maximal speeds is due to muscle contraction not tendons. Still good tendons help transfer force production to the bones and whilst tendon ‘hypertrophy’ may seem like a strategy to facilitate this, in reality the tendon is strong enough and more importance should be placed to the alignment of tendon fibers which requires good recovery time and recovery/repair techniques.