Segment angle. The thigh segment motion in both the standing and sitting positions is similar in time and are the same general shape. However, the maximum and minimum angles of motion differ greatly. The maximum clockwise angle for the sitting biking position is -30 degrees, while the maximum clockwise angle for the standing biking position is 5 degrees. The maximum counterclockwise angle for the sitting biking position was -68 degrees, while the maximum counterclockwise angle for the standing biking position was - 40 degrees. The range of motion for the sitting biking position was 37 degrees, and the range of motion for the standing biking position was 46 degrees.
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Figure 3. Thigh angle during the seated biking position (left) and the standing biking position (right). The thigh angle is calculated from the vertical axis about the hip joint. Anatomical position corresponds to zero degrees. Increasing values indicate clockwise rotation. | |
Joint angle 1. The motion of the knee joint angle during the sitting biking position and the standing biking position differ in the maximum flexion and extension angles, but exhibit similar ranges of motion. The maximum extension angle for the sitting biking position was 154 degrees, and for the standing biking position, the maximum extension angle was 166 degrees. The maximum flexion angle for the sitting biking position was 77 degrees, and for the standing biking position the maximum flexion angle was 90 degrees. The range of motion for the sitting position was 77 degrees, and for the standing position the range of motion was 76 degrees.
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Figure 4. Knee joint angle during the sitting biking position (left) and the standing biking position (right). Knee angle is calculated as the angle between the thigh and the leg. Anatomical position corresponds to 180 degrees. Increasing values represent extension. | |
Joint angle 2. The hip joint motion in the sitting and standing biking positions displays similar ranges of motion and maximum extension and flexion angles. The maximum flexion angle for the sitting biking position was 225 degrees, and for the standing biking position the maximum flexion angle was 253 degrees. The maximum extension angle for the sitting biking position was 197 degrees, and for the standing biking position the maximum extension angle was 199 degrees. The range of motion for the hip joint sitting position was 58 degrees, while for the standing position the range of motion was 53 degrees.
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Figure 5. Hip joint angle during the sitting biking position (left) and the standing biking position (right). Hip joint angle is calculated as the angle between the trunk and the thigh. Anatomical position corresponds to 180 degrees. Increasing values represent flexion. | |
Joint velocity. The knee flexion velocities of the standing and sitting biking positions are similar, whereas the knee extension velocities vary by over 300 degrees/s. The maximum extensor velocity for the sitting position was 221 degrees/s, and the maximum extensor velocity for the standing position was 562 degrees/s. The maximum flexor velocity for the sitting biking position was -264 degrees/s, while the maximum flexor velocity for the standing biking position was -274 degrees/s.
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Figure 6. Knee joint angular velocity in the sitting biking position (left) and the standing biking position (right). Positive values represent extensor velocity. | |
Angle-Angle Plot. The hip's angular motion differs between the standing and sitting biking positions. The sitting position involves a smaller range of motion, while the standing biking position entails a larger range of motion. For the sitting biking position, the movements are completely decoupled. The hip and knee motions in the standing biking position are coupled because the knee and hip are always (except at the switching points) moving with respect to each other during the biking movements. For both the sitting and standing biking positions, there is a lack of coordination at the turning points of the movement. The open oval shapes of both graphs indicate that the joints reach their maxima and do not switch simultaneously, meaning that there is a lack of intersegmental coordination at the switching point. The diagonal lines in the standing biking position angle-angle diagram indicate that there is coordination between the hip and the knee joint.
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Figure 7. Coordination of hip angle and knee angle in the sitting biking position (left) and standing biking position (right). | |
