Figure 3. Thigh angle in the recumbent bike (left) and upright bike (right). Thigh angle is calculated from the vertical. 0 degrees corresponds to anatomical position. Negative values represent counter clockwise rotation.
Segment angle. Segment angle. On the recumbent bike, the thigh rotated in a counter clockwise direction during the first phase and in a clockwise direction during the second phase. The maximum thigh angle of -140 degrees occurred at the end of the first phase at the point of maximum flexion, and the minimum thigh angle of -90 degrees occurred at the beginning of the movement at the point of maximum extension; range of motion was 50 degrees. In the upright bike, the thigh rotated in a counter-clockwise direction during the first phase and in a clockwise direction during the second phase. The maximum angle of -73 degrees occurred at the end of the first phase and the minimum angle of -10 degrees occurred at the beginning of the movement; range of motion was 63 degrees.
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Figure 3. Thigh angle in the recumbent bike (left) and upright bike (right). Thigh angle is calculated from the vertical. 0 degrees corresponds to anatomical position. Negative values represent counter clockwise rotation. | |
Segment velocity. The maximum angular velocity of the thigh segment for the recumbent bike revolution was 117 degrees/sec and occurred during the second phase. The minimum velocity was -133 degrees/sec and occurred during the first phase. In the upright bike revolution, both the maximum and minimum angular velocities were less than the recumbent revolution. The maximum and minimum velocities were both 83 degrees/sec (maximum is positive and minimum is negative).
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Figure 4. Thigh angular velocity in the recumbent bike (left) and the upright bike (right). Positive velocity values represent a clockwise rotation. | |
Joint angle1. The knee joint started in extension, moved into flexion during the first phase and back into extension during the second phase on both bicycles. Both the recumbent and upright maximum and minimum angles were similar. The maximum angles for the recumbent and upright revolutions were 161 degrees and 160 degrees respectively, and occurred at the beginning and end of each revolution. The minimum angles for the recumbent and upright revolutions were 67 degrees and 60 degrees respectively. The minimum angle for the recumbent revolution (maximum flexion) occurred at 2.5 seconds into the movement, 50% of the cycle. The minimum angle for the upright revolution (maximum flexion) occurred at 2.0 seconds into the movement, 40% of the cycle. The recumbent bike elicited a range of motion of 94 degrees and the upright bike elicited a range of motion of 97 degrees.
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Figure 5. Knee joint angles in the recumbent bike (left) and the upright bike (right). Knee angle is calculated counter clockwise from the thigh segment. Anatomical position corresponds to 185 degrees (full extension). Knee flexion occurs as the angle decreases. | |
Joint angle 2. The hip joint started in extension, moved into flexion during the first phase and back into extension during the second phase. The minimum angles (maximum extension) for the recumbent and upright revolutions were 240 degrees and 194 degrees respectively, and occurred at the beginning and end of each revolution. The maximum angle for the recumbent revolution (maximum flexion) was 297 degrees and occurred at 2.9 seconds into the movement, 58% of the cycle. The maximum angle for the upright revolution (maximum flexion) was 264 degrees and occurred at 2.4 seconds into the movement, 48% of the cycle. The recumbent bike elicited a range of motion of 57 degrees, and the upright bike elicited a range of motion of 70 degrees.
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Figure 6. Hip angles in the recumbent bike (left) and the upright bike (right). Hip angle is calculated counter clockwise from trunk segment. Anatomical position corresponds to 180 degrees. Angles greater than 180 correspond to hip flexion. | |
Angle-Angle Plot. Coordination between the knee and hip joints was similar for both the recumbent and upright stationary bikes. In general, the knee flexed while the hip flexed (down and right diagonal in Fig. 7). Starting from an extended position, the knee and hip flexed while the pedal moved toward the body (back for recumbent and up for upright) and both knee and hip extended as the pedal moved away from the body back to the starting position. The primary difference in the knee-hip coordination was the amount of flexion the hip experienced. While the knee range of motion remained nearly the same for both bikes, the hip joint was in a much more flexed position throughout the revolution performed on the recumbent bike.
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Figure 7. Coordination of knee and hip angles in the recumbent bike (left) and the upright bike (right). Arrows indicate direction of movement. Starting position is at the tail of the arrow. | |
