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Video gait analysis is a process where a runner or walker is videotaped. An analyst with a computer watches the video at regular speed, slow motion, and stop motion to assess the individual's stride. Both athletes and people who have trouble walking benefit from video gait analysis. Athletes benefit from video gait analysis because the analyst can observe the stride, and show the athlete ways that they can move more efficiently, either to become faster or prevent injury. People who have trouble walking, benefit from video analysis because the analyst can point out movement and posture related issues that the person could correct through therapy.
Video gait analysis takes place in a lab equipped with multiple cameras, placed around a treadmill. The runner or walker has small reflective markers placed on different landmarks on his or her body, such as points on the knees, ankles, and pelvis. The patient walks or runs for roughly 30 seconds. The movement of the markers are tracked by the computer, which calculates force and trajectory at each point. A computer model provides the analyst a detailed analysis of the movement at each joint.
One of the common types of video gait analysis is to determine how a runner places his or her foot while running. The leg of a runner who has a neutral stride, moves in perfect alignment from knee to foot. The foot of an overpronator shifts to the inside during the running stride. A runner who underpronates will find his or her foot shifts to the outside while running. Once diagnosed, there are therapeutic shoes and inserts that can help neutralize the stride, and relieve stress from under or over-pronating.
One form of video gait analysis is used to determine a person's risk of falls. This method uses the gait abnormality rating scale (GARS). GARS analyzes 16 different parts of the body, five overall, seven on the trunk, upper body, and head, and four on the lower body. Each area is given a rating from zero, which is good, to three which is poor. The combined score provides a baseline to determine if the participant is at a high risk for falls.
A relatively new use for video gait analysis is in the field of biometrics. Biometrics is the process used to identify people, based on certain, unchanging aspects of their body or character. Gait analysis falls under behavioral biometrics, which also includes voice and typing rhythm. The other form of biometrics is physiological, which includes identity screenings such as palm and finger prints, DNA, and iris and facial recognition.