Human Gait Study
Many students wear heavy backpacks to carry their personal belongings. This places additional weight on the human body, shifting their center of mass and leading to changes in gait. To better quantify these effects, a motion capture study was conducted to analyze how backpack weight leads to changes in posture and joint dynamics. A backpack at 20% of the weight of the subject lead to 5.88 degrees of additional forward lean, decreased stride length by 10.1%, and promoted greater external rotation in the ankles.
Human gait describes body dynamics associated with walking and running. In this study, we used a Qualisys motion capture camera system (similar to systems used in sports video game development) to analyze the effects of a weighted backpack on a subject’s gait motion.
The motion capture system consists of a 12-camera system that captures the position of retroreflective markers in space as a function of time. There are two types of markers used in this study, anatomical, which locate joints, and cluster, which is a system consisting of three markers used to identify the location and orientation of the limbs and other body features. The combined use of these markers addresses key sources of noise within the data allowing for greater modelling capabilities. MATLAB was used to post-process the data, calculating joint angles using transformation matrices and Euler angles. The image below highlights the marker sets that were used for this analysis. Base line tests were conducted to establish the unweighted gait for the subject, and then compared to tests cases that gradually increased the weight of the backpack.
The degrees of freedom knee joints were analyzed to understand how the added weight affects flexion, internal rotation, and abduction. While in the ankle, dorsiflexion, internal rotation, and inversion were tracked. Additionally, the adjustment in the trunk angle (angle between chest and the ground) of the subject was of particular interest due to the anticipated forward leaning response often used to counter the increased moment about the spine.
A more detailed report of this study and its findings are shown below.