Article

# Trunk density profile estimates from dual X-ray absorptiometry.

Department of Health and Human Performance, Texas A&M - Commerce, P.O. Box 3011, Commerce, TX 75429, USA.

Journal of Biomechanics (Impact Factor: 2.72). 02/2008; 41(4):861-7. DOI:10.1016/j.jbiomech.2007.10.022 Source: PubMed

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**ABSTRACT:**As accurate body segment inertial parameters (BSIPs) are difficult to obtain in motion analysis, this study computed individual BSIPs from DXA scan images. Therefore, by co-registering areal density data with DXA grayscale image, the relationship between pixel color gradient and the mass within the pixel area could be established. Thus, one can calculate BSIPs, including segment mass, center of mass (COM) and moment of inertia about the sagittal axis (Ixx). This technique calculated whole body mass very accurately (%RMSE of < 1.5%) relatively to results of the generic DXA scanner software. The BSIPs of elite male and female swimmers, and young adult Caucasian males (n = 28), were computed using this DXA method and 5 other common indirect estimation methods. A 3D surface scan of each subject enabled mapping of key anthropometric variables required for the 5 indirect estimation methods. Mass, COM and Ixx were calculated for seven body segments (head, trunk, head + trunk, upper arm, forearm, thigh and shank). Between-group comparisons of BSIPs revealed that elite female swimmers had the lowest segment masses of the three groups (p < 0.05). Elite male swimmers recorded the greatest inertial parameters of the trunk and upper arms (p < 0.05). Using the DXA method as the criterion, the five indirect methods produced errors greater than 10% for at least one BSIP in all three populations. Therefore, caution is required when computing BSIPs for elite swimmers via these indirect methods, DXA accurately estimated BSIPs in the frontal plane. Key PointsElite swimmers have significantly different body segment inertial parameters than young adult Caucasian males.The errors computed from indirect BSIP estimation methods are large regardless whether applied to elite swimmers or young adult Caucasian males.No indirect estimation method consistently performed best.Journal of sports science & medicine 01/2013; 12(4):761-75. · 0.89 Impact Factor - [show abstract] [hide abstract]

**ABSTRACT:**Human modeling and the biomechanical analysis of human movement require the accurate estimation of body segment parameters for various populations and individuals. In this study, the body characteristics of adult Koreans were investigated using three-dimensional range scan data for 40 males and 40 females aged between 18 and 59 years obtained from the SizeKorea anthropometric database. Each subject was divided into 16 segments, and the mass-inertial parameters of each segment were calculated under the assumption of a uniform density distribution for the segment. The length and at least one circumference of each segment were determined from the scan data for that segment. Nonlinear regression equations were then derived based on the segment lengths and circumferences. The body segment parameters of Korean adults can be estimated using these equations if the required dimensions are measured directly or derived from an anthropometric database.Applied ergonomics 01/2011; 42(2):297-308. · 1.11 Impact Factor - [show abstract] [hide abstract]

**ABSTRACT:**Classical models to estimate the head and trunk (HT) moments of inertia (I) are limited to populations from which the anthropometric measures were obtained. The purposes of this study were to determine if the angular momentum technique can be used to estimate subject-specific HT's I values and test its validity and sensitivity. Twenty-three adults who participated in this study were divided into three morphological groups according to their body mass index (BMI). Using the proposed technique, the HT's I values were estimated for the whole sample and compared to three well-known methods to test its validity. The sensitivity of the proposed method was verified while applied to individuals with different BMI (i.e., lean, normal, and obese). The angular momentum technique gave I values within the range of those of the three methods for the entire sample. Statistical differences were identified between the lean and obese groups in relative radii of gyration for the anteroposterior and mediolateral axes ( P<0.05). Since the proposed technique makes no assumption on the mass distribution and segments' geometry, it appeared to be more sensitive to body morphology changes in estimating the HT's I values in lean and obese subjects compared to the classical methods.IEEE transactions on bio-medical engineering 12/2010; 58(5):1278-85. · 2.15 Impact Factor

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