Body Segment Inertial Parameters of Toddlers

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Jackson, Erika
Body Segment Inertial Parameters , Anthropometrics , Toddler , Body Segment Parameters , Photogrammetric
Body segment inertial parameters (BSIPs) are required to study human kinetics and to model the human form. The purpose of this study was to determine the BSIPs in toddlers using the photogrammetric method. Twelve male and twelve female toddlers (1.5-3years) were photographed in two planes, front and side, with reflective markers placed at the joint centres. The subjects were also weighed and had their height measured. Jensen’s elliptical model was used to segment the images and zone the segments in 3mm thick slices. The segment masses, centre of mass (COM) locations and radii of gyration (ROGs) about the three principal axes were calculated and normalized in a percent form. Segment mass proportion of the head was found to decrease as the child ages while the mass proportion of the thigh increases. The trunk’s mass proportion increased with body mass index. These trends follow those found in the literature. The COM locations of segments were compared to the literature. The COM location of the head moves distally as the child ages. The COMs of the thigh and shank move proximally as muscle mass is developed. ROGs were highly variable due to posture variability from a population who found the photogrammetric protocol difficult to follow. To minimize positional errors, all subjects were analyzed together. The arm, forearm, thigh and shank were found to be similar to the literature while the hand and foot differed due to protocol difficulties. The ROGs of the head, neck and trunk could not be compared to the literature due to segmenting differences. The estimated total body mass was compared to the measured mass using a scale. The average error was 1.7% (SD=2.9%). Despite some challenges and limitations of working with toddlers, the study was able to collect BSIPs of toddlers and provide data for a frequently overlooked population. The results of this study provide important data for those studying the biomechanics of toddlers or developing models of toddlers.
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