| 1. Run |
| Criterion 1 |
Arms move in opposition to legs, elbows bent |
Arm-rotation direction is defined as the cross product of left/right upper-arm vectors (shoulder to elbow joint) in two consecutive frames
Leg-rotation direction is defined as the cross product of left/right upper-leg vectors (hip to knee joint) in two consecutive frames
Proportion of frames in which the dot product of the arm-rotation vector and leg-rotation vector is smaller than zero, with bending elbow at the same time, is above a threshold (48.6%) |
| Criterion 2 |
Brief period where both feet are off the ground |
Ground level is estimated on the basis of the subject’s standing position
Duration of both feet being off the ground is above a threshold (0.03s) |
| Criterion 3 |
Narrow foot placement with landing on heel or toe (i.e., not flat footed) |
Proportion of frames with foot angle is above a threshold (57.6%) |
| Criterion 4 |
Non-supporting leg bent to approximately 90° (i.e. heel close to buttocks) |
Mean average of the maximum left and right non-support leg bend angle is above a threshold (131.0°) |
| 2. Gallop |
| Criterion 1 |
Arms bent and lifted to waist level at takeoff |
Proportion of frames in which arms are above the waist level and elbows bend is above a threshold (78.8%) |
| Criterion 2 |
A step forward with the leading foot followed by a step with the trailing foot to a position adjacent to or behind the leading foot |
Motion direction vector is constructed by the mean hip positions (midpoint of left and right hip) of the current and previous frame. If foot direction vector (right to left foot) has the same direction as the motion direction vector, the left foot is the leading foot, and vice versa for different direction
Proportion of frames in which one foot is the leading foot is above a threshold (83.7%) |
| Criterion 3 |
Brief period where both feet are off the floor |
Ground level is estimated according to the subject’s standing position
Duration of both feet above ground is above a threshold (0.03s) |
| Criterion 4* |
Maintains a rhythmic pattern for a minimum of four consecutive gallops |
In a gallop, one leg is always the leading foot; that is, the legs are not crossing. One cycle of gallop is detected when distance between two feet increases and then decreases
Number of right-to-left or left-to-right gallop is 4 or above |
| 3. Hop |
| Criterion 1 |
Non-supporting leg swings forward in a pendular fashion to produce force |
Difference of the maximum and minimum value of leg swing angle is above a threshold (88.2°) |
| Criterion 2 |
Foot of non-supporting leg remains behind body |
Proportion of frames wherein the non-supporting leg is behind the hip is above a threshold (66.3%) |
| Criterion 3 |
Arms flexed and swing forward to produce force |
Proportion of frames wherein arm swings forward during takeoff is above a threshold (98.2%) |
| Criterion 4* |
Takes off and lands a minimum of three consecutive times on preferred foot |
A hop is counted during a single foot landing while the other foot is behind the hip
For criterion 4, number of hops with preferred foot is 3 or above
For criterion 5, number of hops with non-preferred foot is 3 or above |
| Criterion 5* |
Takes off and lands a minimum of three consecutive times on the other foot |
| 4. Leap |
| Criterion 1 |
Take off on one foot and land on the other foot |
Number of leaps with left or right leg take-off is 1 only |
| Criterion 2 |
A period where both feet are off the ground longer than running |
Duration of both feet above ground for a single leap is above a threshold (0.03s) |
| Criterion 3 |
Forward reach with the arm opposite the lead foot |
Right/left arm forward reach angle is above a threshold (40.9°) with left/right foot takeoff |
| 5. Horizontal Jump |
| Criterion 1 |
Preparatory movement includes flexion of both knees with arms extended behind body |
Maximum arm backward swing angle with bending leg is above a threshold (41.3°) |
| Criterion 2 |
Arms extended forcefully forward and upward, reaching full extension above the head |
Mean average of left and right arm forward swing angles is above a threshold (91.6°) |
| Criterion 3 |
Take off and land on both feet simultaneously |
Proportion of frames with time difference between the two legs in a takeoff/landing motion is less than 600ms is above a threshold (60.2%) |
| Criterion 4 |
Arms are thrust downward during landing |
Angle of both arms relative to the horizontal plane during landing (90° – Average angle between the upper arms and the negative Y axis) is above a threshold (10.74°) |
| 6. Slide |
| Criterion 1 |
Body turned sideways so shoulders are aligned with the line on the floor |
For a shoulder-direction vector (left to right shoulder joint) has the same direction as a motion vector (subtraction of the mean hip position of the previous frame and current frame), i.e., their dot product > 0, the motion is classified as being parallel to the shoulders
Proportion of frames motion with parallel shoulder is above a threshold (82.1%) |
| Criterion 2 |
A step sideways with the leading foot followed by a slide of the trailing foot |
In a slide, one leg is always in front of the other; that is, the legs are not crossing. One cycle of slide is detected when the distance between the two legs increases and then decreases.
Mean average number of left-to-right and right-to-left slides is 4 or above |
| Criterion 3 |
A minimum of four continuous step–slide cycles to the right |
Number of left-to-right slides is 4 or above |
| Criterion 4 |
A minimum of four continuous step–slide cycles to the left |
Number of right-to-left slides is 4 or above |