Effects of Cooling on Ground Reaction Forces, Knee Kinematics, and Jump Height in Drop Jumps

This study investigated the effect of knee joint ice application on vertical ground reaction forces (VGRF), knee angle (KA), and jump height (JH) during a single-leg drop jump in 20 healthy participants randomly assigned to an experimental or control group. VGRF were measured using a force plate, KA was measured using an electrogoniometer, and JH was derived from VGRF. After the pretests, a crushed-ice bag was applied to the experimental group participants for 20 minutes, whereas the control group rested. All participants were retested immediately and again after 20 minutes of rest. Significant decreases in average braking phase VGRF (–0.18±0.14 body weight) and increases in contact time (51±39 ms) were found after icing. In addition, several nonsignificant trends toward force reduction were identified. These findings support the statement that when athletes return to competition after icing, an altered neuromuscular behavior might lead to potential re-injury situations.