Joint Position. The linear displacement of the elbow was nearly identical between the two bowstrokes. The bowstroke of the bent endpin cello had a horizontal and vertical displacement of 0.17m and 0.16m, respectively. In comparison, the straight endpin cello had a larger horizontal displacement of 0.18m and a smaller vertical displacement of 0.15m.
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Figure 8. Linear displacement of the elbow in bowstroke with bent endpin (left) and straight endpin (right). Increasing values represent movement to the right in the horizontal direction and upward movement in the vertical direction. The blue line represents the horizontal position and the red line represents the vertical position. | |
Joint velocity. The linear velocity of the elbow was identical between the two movements. The maximum horizontal (right) velocity of both the bent endpin and straight endpin cello bowstrokes was 0.19 m/s. In addition, both cellos had the same maximum upward velocity of 0.19 m/s.
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Figure 9. Linear velocity of the elbow in bowstroke with bent endpin (left) and straight endpin (right). Positive values represent movement to the right in the horizontal direction and upward movement in the vertical direction. The blue line represents the horizontal velocity and the red line represents vertical velocity. | |
Center of mass. The center of mass for both bowstrokes was found in the same area. In both examples, it was located medially to the elbow joint. The center of mass was calculated during full extension of the elbow. The bowstroke involving the bent endpin cello had a center of mass 0.04m to the right and 0.0m above the elbow joint. The center of mass in the straight endpin cello bowstroke was present 0.04m to the right and 0.0m above the elbow joint. Both graphs were taken at peak extension.
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Figure 10. Location of the center of mass (COM) in the movement with bent endpin (left) and straight endpin (right). Body segments shown are the upper arm, forearm, and hand. | |
