Which description accurately defines the stretch-shortening cycle?

• A. Concentric contraction only
• B. Rapid shortening (concentric) followed by a brief amortization (isometric) followed by concentric contraction
• C. Rapid lengthening (eccentric) followed by relaxation
• D. Isometric contraction only

Answer: (C)

The stretch-shortening cycle is a sequence where a rapid eccentric stretch is followed by a brief amortization phase, and then a powerful concentric contraction. The key idea is that the quick lengthening stores elastic energy in the muscle–tendon system and, with a short pause, this energy plus reflex mechanisms are released to produce a stronger subsequent shortening.

This is best described by a rapid lengthening (eccentric) that is quickly followed by a brief amortization (isometric) phase, then a concentric contraction. That combination uses the stored energy and the stretch reflex to boost force, which is why it yields greater power than a single concentric action or a stretch without the subsequent shortening.

Descriptions that involve only concentric contraction, only isometric contraction, or a rapid lengthening without a follow-up shortening don’t capture the whole sequence and the performance benefits of the stretch-shortening cycle.