RESULTS: Angular Kinematics

Segment angle. As seen by the graphs, the trunk segment angle decreased more in the basketball shoe jump than in the jump with the strength shoes. The indicated greater flexion in the basketball shoe jump because anatomical position, at the start, is 0 degree and the trunk moves counterclockwise to the vertical axis. In the basketball shoe jump our subject started at a position slightly less than full extension (-5 deg) where as the jump with the strength shoes, our subject began in full extension (0 deg). The smallest angle on these graphs represented the maximum flexion of the trunk segment. Our subject showed greater flexion in the basketball shoe jump compared to the strength shoe jump, -60 deg to &endash;50 deg respectively. The time from extension to flexion and back to extension took the same amount of time in both jumps, but peaked at different angles.

Figure 3. Trunk angle during the basketball shoe jump (left) and the strength shoes jump (right). The trunk angle is calculated from the vertical axis about the hip. Anatomical position corresponds to zero degrees. Increasing values represent clockwise rotation.

Joint angle 1. The following graphs show that the ankle angle during the basketball shoe jump was much more stable than the ankle angle jumping in strength shoes. The jagged line representing strength shoe ankle angle movement shows that during the jump the ankle angle varied considerably more than with basketball shoes. Dorsiflexion is increasing angle values. At the start of the strength shoe jump the ankle angle was greater than 250 deg, the anatomical position value, which indicates dorsiflexion. Both jumps peaked at similar ankle angles (300 deg).

Figure 4. Ankle angle during the basketball shoe jump (left) and the strength shoe jump (right). Ankle angle is calculated as the angle between the foot and the leg. Anatomical position corresponds to 250 degrees. Increasing values represent dorsiflexion.

Joint angle 2. These graphs show that more knee extension occurred in the landing phase of the basketball shoe jump than the strength shoe jump. Increased knee flexion is indicated by decreasing angle values on the vertical axis. Beside this increased flexion in the basketball shoe landing, the peak knee extension and flexion angles were similar in both jumps. Both graph had peak flexion angles around 90 deg and peak extension at 200 deg, these angles were with respect to the anatomical starting position value of 180 deg on the vertical axis.

Figure 5. Knee angle during the basketball shoe jump (left) and the strength shoe jump (right). Knee angle is calculated as the angle between the leg and the thigh. Anatomical position corresponds to 180 degrees. Increasing values represent extension.

Joint velocity. The basketball shoes jump showed two distinct peaks, one for plantarflexion (negative values) and dorsiflexion (positive values). The strength shoe jump showed greater variablilty in illustrating peak velocities. The peak dorsiflexion velocity is greater for the basketball shoe jump, 700 degs/sec compared to the 500 deg/sec of the strength shoes. The plantarflexion values are the same for both jumps (-1000 deg/s).

Figure 6. Ankle angular velocity in the basketball shoe jump (left) and the strength shoe jump (right). Positive values represent dorsiflextion velocity.

Angle-Angle Plot. Illustrated in these graphs are knee angle and ankle angle turning point synchronization, which is indicated by the different joint angles switching their position simultaneously. Dorsiflexion (increasing horizontal values) occurred at the same time as knee flexion; plantarflexion and knee extension occurred simultaneously as well. Full extension was represented by +180 deg on the vertical axis. Anatomical starting position of ankle is represented by +250 deg on the horizontal axis. Both patterns are similar. A linear line for basketball shoes indicates more coordination between joints.

Figure 7. Coordination of knee angle and ankle angle in the basketball shoe jump (left) and the strength shoe jump (right).