Segment angle. In walking the maximum thigh segment angle (52 deg.) occurs at the end of the swing phase, which is consistent with the maximum hip flexion. The minimum angle occurs when the cat changes from stance to swing phases (9 deg). The stance phase is from the minimum angle to the maximum angle. Heel strike, when the paw is put back onto the ground, is the minimum angle. Toe off, when the toe lifted off the ground for the next step cycle, is the maximum angle. The total range of motion is 43 deg.
In trotting the thigh segment angles are similar to walking, but the cycle time is shorter for trotting. The thigh segment angle is greatest (54 deg) at the end of the swing phase. The angle is smallest (4 deg) during the change from stance to swing. The total range of motion is 50 deg.
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Figure 3. Thigh angle during walking (left) and trotting (right). The thigh angle is calculated from the vertical to the thigh at the proximal end. As the angle increases, flexion increases. Positive values in the chart correspond to clockwise rotation of the angle. | |
Segment velocity. The maximum angular velocity in walking is 200 deg/sec and the minimum is -133 deg/sec. For trotting the maximum was 433 deg/sec and the minimum is -233 deg/sec. The peak velocity occurs sooner in trotting, at 65% of the cycle. In walking it occurred at 75% of the cycle. The minimum velocity occurred at the beginning of the cycle for both movements.
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Figure 4. Thigh angular velocity in walking (left) and trotting (right). Positive velocity represents clockwise rotation (hip flexion). | |
Joint angle1. In walking, the minimum knee angle (maximum flexion) is 67 deg. and the maximum knee angle (extension) is 108 deg. The range of motion is 41 deg. Both occur during the swing phase. In trotting, the minimum joint angle in the knee is 59 deg. while the maximum joint angle is 121 deg. The range of motion is 62 deg. The minimum angle occurs at the beginning of the swing phase and maximum angle is at the end of the swing phase.
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Figure 5. Knee angle in walking (left) and trotting (right). The joint angle is clockwise from the thigh to the leg segment. As the angle increases extension increases. As the angle decreases, the leg flexes and the knee is in flexion. Increasing angle corresponds to extension, while decreasing angle corresponds to flexion. | |
Joint angle 2. In walking, the minimum ankle angle (dorsiflexion) is 70 deg. while the maximum ankle angle is 115 deg. The range of motion is 45 deg. In trotting, the minimum ankle joint is 45deg. and the minimum ankle joint angle is 116 deg. The range of motion is 71 deg. For both movements, the maximum angle, corresponding to plantarflexion, occurred at the beginning of the swing phase and the minimum angle, corresponding to dorsiflexion, occurred in the middle of the swing phase.
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Figure 6. Ankle angle in walking (left) and trotting (right). The angle is calculated by measuring counterclockwise from the leg segment to the paw segment. Increasing angle corresponds to plantar flexion, while decreasing angle corresponds to dorsiflexion. | |
Angle-Angle Plot. During stance phase of the walking gait, the knee angle remains fairly constant while the thigh extends from 43 deg. to 9 deg. While the knee reverses in a neutral position, the thigh angle moves from flexion to extension back to flexion. During the trotting movement, both the knee and thigh angles have large ranges of motion. The knee angle ranges from 60 deg. to 120 deg. and the thigh angle ranges from 5 deg. to 55 deg. The knee moves from a neutral position through flexion to extension, while the thigh angle moves from a neutral position through extension to flexion. In walking, the time in which the joints are most highly coordinated occurs during the swing phase. This is more noticeable in the trotting movement.
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Figure 7. Coordination of knee and ankle in walking (left) and trotting (right). The open-headed arrows represent the direction of the movement. | |
