Most previous standing long jump studies have been based on the assumption of twodimensional sagittal plane motion. The purpose of this study was to investigate the validity of this assumption. Standing long jump trials were collected using six adult male subjects. Each subject stood with a foot on each of two force plates and performed eight standing long jumps for maximal distance. Inverse dynamics analyses were performed for the two-dimensional (2D) and three-dimensional (3D) models and the joint moments, powers, and work values were compared. The differences between these models with respect to the validity of the common planar jumping assumption were analyzed.

Good agreement was observed between the 2D and 3D methods for the lower body, with little difference in the moments, power, and work for the ankle, knee, hip, and lower back. For the upper body, the moments and work were similar, however significant differences were observed in power generation resulting from the two methods. There were also significant moments and power generated about the abduction/adduction axis for the shoulder. An approximately equal amount of work was found to be performed about the abduction/adduction and flexion/extension axes at the shoulder. The 3D model was also found to capture significant differences between the left and right sides of the body that were not able to be observed with the 2D model.

The results of this study show that a planar motion assumption should be sufficient for most studies of the standing long jump. However, in cases where upper body motion is being studied or small increases in performances are vital, a 3D model may be more appropriate as it more accurately represents the motion of the upper body and is better able to show the differences in performance between the two sides of the body