From the results obtained in the biomechanical analysis, the two foot jump is more capable of optimizing performance than the one foot jump based on the maximum vertical displacement of each. In comparison, there is a distinct height advantage for the two foot jump. The height advantage is a result of differences in the thigh segment velocities as well as the knee and ankle angles between the two jumps.
The segment velocity analysis showed a greater clockwise rotation of the thigh in the preparatory and descending phases of the two foot jump. Other noteworthy differences between the two movements occur in the preparatory and descending phases. In the preparatory phase of the two foot jump, there was greater knee flexion and greater ankle dorsiflexion. In the descending phase, greater ankle plantarflexion was observed. Also, in the two foot jump, greater clockwise rotation of the thigh segment angle and the resulting counterclockwise rotation in the descending phase were attributable to the subsequent generation of contractile properties of jumping. The greater angles of the knee and the ankle are necessary to generate the additional muscle torque responsible for the larger vertical displacement in the two foot jump. Muscle torque is a product of the muscle force and the moment arm. Lengthening the moment arm allows for greater muscle torque.
Limitations in the movement we chose as well as technical restraints in the biomechanical analysis may have affected the results obtained. For example, if we chose to compare the differences between a one foot and two foot jump starting from a standstill (without the two step approach) the results may have differed. Also, the joint markers were placed on each frame of the movements by hand, so they are only as accurate as the human eye and the computer mouse will allow. Finally, the video was digitized at 30 frames/s. If the video was digitized at a higher frame per second, the movement would be analyzed more accurately.
Bobbert, Maarten F., Gerritsen, Karen G.M., Litjens, Maria C.A., and Van Soest, Arthur. Why is countermovement jump height greater than squat jump height? Medicine & Science in Sports & Exercise. Vol.28 No.11: 1402-1412, November 1996.
Holloszy, John 0. Exercise and Sport Sciences Reviews : Volume 24. Baltimore: Williams & Wilkins, 1996, pp. 192-194.