Segment angle. Segment Angle. The absolute angle of the trunk was analyzed for one complete crunch via the conventional crunch and the abdominal leg raise. The abdominal leg raise showed a smaller range of motion (3 deg) progressing from 3 degrees (anatomical position) to 6 degrees (peak flexion at height of crunch) and then back to 2 degrees (human error may have accounted for the change in the initial position). The maximum angle (where the knees reached mid torso level) occurred at the clockwise to counterclockwise motion. The conventional crunch had a greater range of motion (30 deg) progressing from 89 degrees (anatomical position) to 60 degrees (peak flexion at height of crunch) and then back to 89 degrees. The minimum angle (most upright position) occurred at the transition from counterclockwise to clockwise motion.
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Figure 3. The trunk segment angle (thoracic spine and lumbar spine) during the abdominal leg raise (left) or the conventional crunch (right). The segment angle is calculated from the vertical. The anatomical position for the abdominal leg raise (left) is 0 degrees. The anatomical position for the conventional crunch (right) is 90 degrees. Increasing values represent clockwise rotations.
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Joint angle 1. Range of motion at the hip joint was greater in the abdominal leg raise (107 deg) than during the conventional crunch (28 deg). Peak hip extension was greater in magnitude during the abdominal leg raise (180 deg) and during the conventional crunch (101 deg). Maximum extension for the conventional crunch and the abdominal leg raise occurred at the initial and final position of the movements. Peak hip flexion was also greater during the abdominal leg raise (287 deg) which occurred at 1.45s (53% of total time). In the conventional crunch peak flexion occurred at (129 deg) which occurred at 1.32s (34% of total time).
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Figure 4. Hip joint angles in the abdominal leg raise (left) and the conventional crunch (right). The joint angle is calculated by the relative positions of the shoulder, hip, and knee joint markers. 180 degrees corresponds to anatomical position for abdominal leg raise (left). 90 degrees corresponds to anatomical position for the conventional crunch. For both movements, increasing angles represent flexion.
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Joint angle 2. Range of motion of the knee joint was greater during the abdominal leg raise (112 deg) then the conventional crunch (-9 deg). Peak knee extension is greater in magnitude during the abdominal leg raise (165 deg) due to the continuous flexion of the knees in the conventional crunch. Maximum extension for the abdominal leg raise occurred at the initial and at the end of the motion. Peak knee flexion during the abdominal leg raise (53 deg) occurred at 1.42s (52% of the total time). Peak knee flexion during the conventional crunch (268 deg) occurred at 1.98s (51% of the total time). It should be noted that peak angles for these two movements are measured relative to two different axis.
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Figure 5. Knee joint angle in the abdominal leg raise (left) and the conventional crunch (right). The joint angle is calculated by the relative positions of the ankle, knee, and hip. 180 degrees corresponds to the anatomical position for the abdominal leg raise (left). 270 degrees corresponds to the anatomical position for the conventional crunch (right). In the abdominal leg raise (left), increasing angles represent extension. In the conventional crunch (right), increasing angles represent flexion.
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Joint velocity. The joint angular velocity was different between the two movements. Peak velocity in the ascent phase (flexion) was greater in the abdominal leg raise (281 deg/s) than during the conventional crunch
(46 deg/s). Peak descent (extension) velocity was -371 deg/s in the abdominal leg raise which was greater than the peak descent velocity for the conventional crunch (-62 deg/s).
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Figure 6. Hip joint angular velocity in the abdominal leg raise (left) and the conventional crunch (right). For both the abdominal leg raise (left) and the conventional crunch (right) positive velocity represents flexion.
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Angle-Angle Plot. The motions of the hip and knee joint angles were coupled in the abdominal leg raise. In the abdominal leg raise as the knee angel decreased (flexion) the hip angle increased (flexion). The hip flexion increased with a decrease in knee angle. In this movement the knees were moving towards the mid torso. As the knee angle remained constant the hip angle decreased (flexion). The upper torso was elevated and brought towards the knees.
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Figure 7. Coordination of hip joint and knee joint angles in the abdominal leg raise (left) and the conventional crunch (right). The arrows indicate the start and end of each movement. In the abdominal leg raise (left) the two joint angles are coupled and are diagonally oriented in a negative slope. In the conventional crunch (right) the hip joint angle is changing and the knee joint angle is held relatively constant. | |
