ABSTRACT
The stretch-shortening cycle (SSC) refers to when an eccentric (lengthening) muscle action is immediately followed by a concentric (shortening) muscle action. The SSC is utilised most frequently during athletic tasks (i.e., running, jumping, hopping) and it leads to superior muscle output (e.g., force) when compared to isolated concentric muscle actions. The two main mechanisms thought to be responsible for the potentiating effect of the SSC are stimulation of muscle stretch reflexes (e.g., muscle spindles) and storage and reutilisation of elastic energy in the muscle-tendon unit. The stiffness of the muscle-tendon unit acts to regulate muscle-tendon length changes during SSC actions, and thus influences muscle spindle activation and elastic energy storage and release. It can be gleaned, therefore, that muscle-tendon stiffness (MTS) influences SSC function, and thus the performance of athletic tasks that include the SSC. The primary aim of this chapter, therefore, isto describe the SSC and how MTS influences SSC function during athletic tasks both acutely and following different training programmes.
