More plyometrics?
This phase is sometimes called the phase of amortization in which the athlete absorbs some of the forces and stops downward movement by the strong eccentric contraction of the muscles. The strong eccentric contraction prepares the muscles to switch to the concentric contraction in an explosive manner for takeoff.
When the athlete drops down to the floor, the body experiences an impact upon landing. The higher the height of the step-off platform, the greater are the impact forces upon landing. This creates a shock to the body which the body responds to by undergoing a strong involuntary muscular contraction to prevent the body from collapsing on the ground. This in turn produces great tension in the muscles and tendons which is then given back in a return upward movement. The faster the change in the muscular contractions, the greater is the power created and the resulting height attained.[16]
More specifically, the muscles and tendons undergo a stretch (eccentric contraction) on the landing which is needed to absorb some of the forces generated but most importantly, to withstand the forces that are produced by the shock that occurs on the landing. The greater the shock (forces experienced on landing), the stronger is the eccentric contraction which in turn, produces even greater tension. This tension which is potential force, is then given back in the return movement when the muscular contractions switch to the concentric or shortening regime.[17]