Importance of countermovement depth in stretching and shortening cycle analysis

The aim of this investigation was to determine the influences of force application related variables and center of mass displacement on jump height differences between squat jump (SJ) and countermovement jump (CMJ). Twenty six males performed three squat jumps and three countermovement jumps with a 90° knee flexion. The center of mass displacement during the upward movement phase and the average force were significantly greater in CMJ than in SJ. Both variables explained 75% of the differences in the flight height, having 30% more influence on the center of mass displacement. There were no differences in peak force. The results of this research suggest the need to examine the center of mass displacement during SJ and CMJ when a 90°of knee flexion criteria is established.