Figure 11. Open and closed-kinetic-chain eccentric quasi-isometric quadriceps contractions.

Eccentric quasi-isometric (EQI) quadriceps resistance training can be completed on a leg press with a decline ankle-wedge (a-c) or knee extension machine (d-f) by (1) performing a concentric contraction to externally load the surgical knee/limb (a, d), (2) performing a yielding/holding isometric contraction to the point of volitional fatigue/failure (b, e), and (3) continuing to maximally resist the ensuing eccentric contraction throughout the prescribed range of knee motion. Black arrows, contraction direction; black lines, approximate tibial and femoral bone markers; green shading, concentric contractions; red shading, ensuing eccentric contractions as part of the EQI contraction; white asterisk, heel wedge; white circle, estimated center of joint rotation; yellow shading, depiction of large external knee flexion moment during yielding/holding isometric contractions