Segment angle. The range of motion varied for the two push-ups because the upper arm segment had to form a greater angle to reach the correct downward position (chest almost parallel to the floor) during the knee push-up. For both push-ups, the maximum angle was achieved at the most downward position of the push-up and the minimum angle was achieved at the starting position. Although the minimum angles were similar for both push-ups, the maximum angles were different by 20 degrees. During the knee push-up the minimum angle was -1 degree and the maximum was -100 degrees. For the regular push-up the minimum angle was 2 degrees and the maximum angle was -80 degrees. The maximum angle was achieved at peak counterclockwise rotation and the minimum angle was achieved at peak clockwise rotation. The range of motion for the upper arm during the knee push-up was 99 degrees and 82 degrees for the regular push-up.
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Figure 3. Upper arm angle during the knee push-up (left) and regular push-up (right). Upper arm angle is measured from the vertical axis. When the upper arm is at zero degrees it is in the vertical position perpendicular to the ground. Decreasing values represent counterclockwise rotation, while increasing values represent clockwise rotation of the upper arm for both figures. | |
Joint angle 1. The range of motion was the same for the two push-ups even though the shoulder joint had to form a greater angle to reach the correct downward position (chest almost parallel to the floor) during the knee push-up. During the knee push-up the peak extension angle was achieved at the start position of the push-up and the peak flexion angle was achieved at the most downward position. The peak extension angle was 57 degrees and the peak flexion angle was -23 degrees. During the regular push-up the peak extension and flexion angles were achieved at the same positions as the knee push-up trial. The peak extension angle was 77 degrees and the peak flexion angle was -3 degrees. The maximum (peak extension) angles were achieved at peak clockwise rotation and the minimum (peak flexion) angles were achieved at peak counterclockwise rotation. The range of motion for both types of push-ups was 80 degrees.
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Figure 4. Shoulder joint angle during knee push-up (left) and regular push-up (right). Joint angle is measured between the trunk and the upper arm segments. When the upper arm is at zero degrees it is in the vertical position perpendicular to the ground. Decreasing values represent flexion in a counterclockwise direction, while increasing values represent flexion in the clockwise direction for both figures. | |
Joint angle 2. The range of motion varied for the two push-ups because the elbow joint had to form a greater angle to reach the correct downward position (chest almost parallel to the floor) during the knee push-up. During the knee push-up the peak extension angle was achieved at the start position of the push-up and the peak flexion angle was achieved at the most downward position. The peak extension angle was 189 degrees and the peak flexion angle was 73 degrees. During the regular push-up the peak extension and flexion angles were achieved at the same positions as the knee push-up. The peak extension angle was 196 degrees and the peak flexion angle was 85 degrees. The maximum (peak extension) angles were achieved at peak clockwise rotation and the minimum (peak flexion) angles were achieved at peak counterclockwise rotation. The range of motion for the upper arm during the knee push-up was 116 degrees and 111 degrees for the regular push-up.
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Figure 5. Elbow joint angle during knee push-up (left) and regular push-up (right). Joint angle is measured between the forearm and the upper arm segments. When the upper arm is at zero degrees it is in the vertical position perpendicular to the ground. Increasing angle represents extension and decreasing angle represents flexion. | |
Joint velocity. Peak flexion velocity at the shoulder joint during the knee push-up was 173 degrees, while during the regular push-up this velocity was 237 degrees per second. Peak extension velocity during the knee push-up was -152 degrees per second, while during the regular push-up this velocity was -189 degrees per second.
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Figure 6. Shoulder angular velocity during knee push-up (left) and regular push-up (right). Positive velocity values represent extension, while negative velocity values represent flexion, for both figures. | |
Angle-Angle Plot. Coordination between the shoulder angle and the elbow angle were similar. The elbow angle was the same in both push-ups. The shoulder angle was greater in the regular push-up. During the regular push-up movement the shoulder and elbow joint values remained positive. During the knee push-up movement the shoulder and elbow joint values remained positive. In both cases the elbow angle changed linearly in relation to the shoulder angle.
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Figure 7. Coordination of shoulder and elbow angles during knee push up (left) and regular push up (right). Arrows indicate direction of rotation, and start position. | |
