RESULTS: Angular Kinematics

Segment angle. The upper-arm segment motion is different in the standard and incline bench press. The maximum clockwise angle of the standard bench press was 147 degrees and the maximum counterclockwise angle was -4 degrees, consequently the range of motion of the movement was 151 degrees. The maximum clockwise angle of the incline bench press was 172 degrees and the maximum counterclockwise angle was 7 degrees, consequently the range of motion of the movement was 165 degrees.

Figure 3. Upper-arm segment angle during the standard bench press (left) and the inclined bench press (right). The upper-arm angle is calculated from the vertical axis about the shoulder joint. Anatomical position corresponds to 90 degrees. Increasing values represent clockwise rotation.

Joint angle 1. The motion of the shoulder joint was different for the standard bench press and the inclined bench press. The maximum flexion angle for the standard bench press was 90 degrees, the maximum extension angle was 240 degrees, and the resulting range of motion of the movement was 150 degrees. The maximum flexion angle for the incline bench press was 242 degrees, the maximum extension angle was 411 degrees, and the resulting range of motion was 169 degrees.

Figure 4. Shoulder joint angle during the standard bench press (left) and the inclined bench press (right). The shoulder joint angle is calculated as the angle of the upper-arm segment and the torso segment. Anatomical position corresponds to 180 degrees for the standard bench press and 360 degrees for the incline bench press. Increasing values represent extension.

Joint angle 2. The elbow joint angle for the standard bench press and incline bench press was different. The maximum flexion angle for the standard bench press was 37 degrees, maximum extension angle was 184 degrees, and the resulting range of motion was 147 degrees. The maximum flexion angle for the incline bench press was 29 degrees, the maximum extension angle was 180 degrees, and the resulting range of motion was 151 degrees.

Figure 5. Elbow joint angle during the standard bench press (left) and the inclined bench press (right). Elbow joint angle is calculated as the angle between the forearm and the upper-arm segment. Anatomical position corresponds to 180 degrees. Increasing values represent extension.

Joint velocity. The angular velocity of the shoulder joint during the standard bench and the incline bench press depicted a similar sinosodial curve. The maximum flexion angular velocity for the standard bench press was &endash;480 deg/s, and maximum extension angular velocity was 512 deg/sec. The maximum flexion angular velocity for the incline bench press was &endash;523 deg/sec, and the maximum extension angular velocity was 348 deg/sec.

Figure 6. Shoulder joint angular velocity in the standard bench press (left) and the inclined bench press (right). Positive values represent extensor velocity.

Angle-Angle Plot. The coordination of the elbow joint and shoulder joint was similar for both the standard bench press and incline bench press. The motion was inversely coupled in both the standard bench press and incline bench press. In other words, as the shoulder joint was flexing the elbow joint was extending and vice versa. This can be determined from Figure 7. For example, in the standard bench press, the elbow joint is around 200 degrees when the shoulder was around 100 degrees. This can be analyzed as the elbow joint in extension while the shoulder joint is in flexion. Analysis of the angle-angle plots for the standard bench press and the incline bench press showed a higher degree of de-coupling in the standard bench press, as indicated by more area within the lines of the plot, than the incline bench press.

Figure 7. Coordination of shoulder angle and elbow angle in the standard bench press (left) and incline bench press (right).