The Squat Jump (SJ) starts with the athlete in a 90° squat position, holds for ≥2 seconds, then jumps maximally upward with no downward dip. Removing the countermovement isolates concentric output, stripping out the elastic and reflex contributions of the stretch-shortening cycle.
The SJ is typically 4–10 cm lower than the same athlete's CMJ. The ratio CMJ ÷ SJ (Eccentric Utilization Ratio, EUR) indexes how much an athlete relies on the stretch-shortening cycle — an EUR significantly above 1 suggests strong reactive ability; close to 1 suggests the athlete is mostly relying on raw concentric strength.
Hardest part of the protocol is enforcing "no countermovement" — video or a coach watching from the side catches the dip.
Where it's used
Lab and field testing batteries, alongside CMJ to compute EUR.
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