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Karen P. DePauw

This study was undertaken to investigate the total body and segmental centers of mass of individuals with Down’s syndrome. The 40 subjects were divided equally by gender into the following age groups: (a) ages 6 to 10, (b) ages 11 to 18, (c) adult females, and (d) adult males. Data on mass centroid locations were collected through a photogrammetric technique. Frontal and right sagittal-view slide photographs on each subject were digitized and the data logged into a computer program. The program calculated the segmental mass centroid locations and total body center of mass. Differences in total body and segmental center of mass locations were found between individuals with Down’s syndrome (DS) and nonhandicapped individuals. Analysis of the data on the DS children indicated that the mean center of mass location for the total body was within the range reported for nonhandicapped children. The adult DS male and female subjects were found to have a lower total body center of mass when compared to existing data on nonhandicapped adults. It was also found that the segmental mass centroid locations for the head and trunk segment of DS subjects were consistently lower than those found in nonhandicapped individuals. This finding points to an overall lowering of the center of mass found with DS subjects.

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Samantha L. Winter, Sarah M. Forrest, Joanne Wallace and John H. Challis

comparing model predicted data with direct whole-body measurements and DXA-derived segmental mass data. The model was similar to that of Yeadon 9 but adapted such that an increased number of measurements are used with the intention of better approximating the trunk segment for female subjects. Note that

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John C. Garner, Chris MacDonald, Chip Wade, Andrea Johnson and M. Allison Ford

The primary objective of this study was to investigate the influence of segmental mass and body composition on the upper extremity biomechanics of overweight youth participating in baseball activities. The study used a regression framework to investigate the relationship between whole body, throwing arm segmental mass and body composition measures to kinetic variables about the shoulder and elbow. The multivariate regression results indicated a strong positive significant relationship between each of the mass variables to that of the moment variables about the shoulder and elbow. Participants who had a greater percentage of fat mass produced greater injury correlated moments about the shoulder and elbow.

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Marianne J. R. Gittoes and David G. Kerwin

This study aimed to gain insight into the individual and interactive effects of segmental mass proportions and coupling properties on external loading in simulated forefoot landings. An evaluated four-segment wobbling mass model replicated forefoot drop landings (height: 0.46 m) performed by two subjects. A comparison of the peak impact forces (GFzmax) produced during the evaluated landing and further simulated landings performed using modified (±5% perturbation) mass proportions and coupling properties was made. Independent segmental mass proportion changes, particularly in the upper body, produced a prominent change in GFzmax of up to 0.32 bodyweight (BW) whereas independent mass coupling stiffness and damping alterations had less effect on GFzmax (change in GFzmax of up to 0.18 BW). When combining rigid mass proportion reductions with damping modifications, an additional GFzmax attenuation of up to 0.13 BW was produced. An individual may be predisposed to high loading and traumatic and overuse injury during forefoot landings owing to their inherent inertia profile. Subject-specific neuromuscular modifications to mass coupling properties may not be beneficial in overriding the increased forces associated with larger rigid mass proportions.

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Matthew T.G. Pain and John H. Challis

This study had two purposes: to evaluate a new method for measuring segmental dimensions for determining body segment inertial parameters (BSIP), and to evaluate the changes in mass distribution within a limb as a consequence of muscular contraction. BSIP were calculated by obtaining surface data points of the body under investigation using a sonic digitizer, interpolating them into a regular grid, and then using Green’s theorem which relates surface to volume integrals. Four skilled operators measured a test object; the error was approximately 2.5% and repeatability was 1.4% (coefficient of variation) in the determination of BSIP. Six operators took repeat measures on human lower legs; coefficients of variation were typically around 5%, and 3% for the more skilled operators. Location of the center of mass of the lower leg was found to move up 1.7 cm proximally when the triceps surae muscles went from a relaxed state to causing plantar flexion. The force during an impact associated with such motion of the soft tissue of the lower leg was estimated to be up to 300 N. In summary, a new repeatable and accurate method for determining BSIP has been developed, and has been used to evaluate body segment mass redistribution due to muscular contraction.

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April J. Chambers, Alison L. Sukits, Jean L. McCrory and Rakié Cham

Age, obesity, and gender can have a significant impact on the anthropometrics of adults aged 65 and older. The aim of this study was to investigate differences in body segment parameters derived using two methods: (1) a dual-energy x-ray absorptiometry (DXA) subject-specific method (Chambers et al., 2010) and (2) traditional regression models (de Leva, 1996). The impact of aging, gender, and obesity on the potential differences between these methods was examined. Eighty-three healthy older adults were recruited for participation. Participants underwent a whole-body DXA scan (Hologic QDR 1000/W). Mass, length, center of mass, and radius of gyration were determined for each segment. In addition, traditional regressions were used to estimate these parameters (de Leva, 1996). A mixed linear regression model was performed (α = 0.05). Method type was significant in every variable of interest except forearm segment mass. The obesity and gender differences that we observed translate into differences associated with using traditional regressions to predict anthropometric variables in an aging population. Our data point to a need to consider age, obesity, and gender when utilizing anthropometric data sets and to develop regression models that accurately predict body segment parameters in the geriatric population, considering gender and obesity.

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Zachary Merrill, Grace Bova, April Chambers and Rakié Cham

arms from the torso, Zatsiorsky and de Leva use planes through the shoulder joint centers parallel to the sagittal plane, while Chambers uses planes perpendicular to the frontal plane through the acromion and axilla. To determine the in vivo trunk parameters, including trunk segment mass, COM, and

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Amy R. Lewis, William S.P. Robertson, Elissa J. Phillips, Paul N. Grimshaw and Marc Portus

maximum isometric force-generating capacity and (2) to compare anthropometric parameters used in the definition of the musculoskeletal model, against subject-specific mass values obtained using DXA. If a close agreement is observed, scaling DXA segment mass values against segment mass values obtained from

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Kevin Deschamps, Giovanni Matricali, Maarten Eerdekens, Sander Wuite, Alberto Leardini and Filip Staes

in each subarea was used as the CoP for each segment in the inverse dynamics calculation. Inertial parameter calculations of the foot segments were based on generic segmental mass calculations. 29 With respect to the IOR-3Segment_model1, the mass of the foot was distributed at 30%, 60%, and 10

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Robert D. Catena, Nigel Campbell, Alexa L. Werner and Kendall M. Iverson

.1016/j.jbiomech.2018.02.004 29463385 21. Jensen RK , Doucet S , Treitz T . Changes in segment mass and mass distribution during pregnancy . J Biomech . 1996 ; 29 ( 2 ): 251 – 256 . PubMed ID: 8849820 doi:10.1016/0021-9290(95)00042-9 10.1016/0021-9290(95)00042-9 8849820 22. Widen E