Body segment parameters of Paralympic athletes from dual-energy X-ray absorptiometry

Estimating body segment parameters from three-dimensional human body scans

Body segment parameters are inputs for a range of applications. Participant-specific estimates of body segment parameters are desirable as this requires fewer prior assumptions and can reduce outcome measurement errors. Commonly used methods for estimating participant-specific body segment parameters are either expensive and out of reach (medical imaging), have many underlying assumptions (geometrical modelling) or are based on a specific subset of a population (regression models). Our objective was to develop a participant-specific 3D scanning and body segmentation method that estimates body segment parameters without any assumptions about the geometry of the body, ethnic background, and gender, is low-cost, fast, and can be readily available. Using a Microsoft Kinect Version 2 camera, we developed a 3D surface scanning protocol that enabled the estimation of participant-specific body segment parameters. To evaluate our system, we performed repeated 3D scans of 21 healthy participants (10 male, 11 female). We used open source tools to segment each body scan into 16 segments (head, torso, abdomen, pelvis, left and right hand, forearm, upper arm, foot, shank and thigh) and wrote custom software to estimate each segment’s mass, mass moment of inertia in the three principal orthogonal axes relevant to the center of the segment, longitudinal length, and center of mass. We compared our body segment parameter estimates to those obtained using two comparison methods and found that our system was consistent in estimating total body volume between repeated scans (male p = 0.1194, female p = 0.2240), estimated total body mass without significant differences when compared to our comparison method and a medical scale (male p = 0.8529, female p = 0.6339), and generated consistent and comparable estimates across a range of the body segment parameters of interest. Our work here outlines and provides the code for an inexpensive 3D surface scanning method for estimating a range of participant-specific body segment parameters.

Baseball Pitching Arm 3-D Inertial Parameter Calculations from Body Composition Imaging and a Novel Overweight Measure for Youth Pitching Arm Kinetics

Many baseball pitching studies have used inverse dynamics to assess throwing arm kinetics as high and repetitive kinetics are thought to be linked to pitching injuries. However, prior studies have not used participant-specific body segment inertial parameters (BSIPs) which are thought to improve analysis of high-acceleration motions and overweight participants. This study's objectives were to 1) calculate participant-specific BSIPs using DXA measures, 2) compare inverse dynamic calculations of kinetics determined by DXA-calculated BSIPs (full DXA-driven inverse dynamics) against kinetics using the standard inverse dynamics approach with scaled BSIPs (scaled inverse dynamics), and 3) examine associations between full DXA-driven kinetics and overweight indices: body mass index (BMI) and segment mass index (SMI). Eighteen participants (10-11 years old) threw 10 fastballs that were recorded for motion analysis. DXA scans were used to calculate participant-specific BSIPs (mass, center of mass, radii of gyration) for each pitching arm segment (upper arm, forearm, hand), BMI, and SMI. The hypotheses were addressed with t-tests and linear regression analyses. The major results were that 1) DXA-calculated BSIPs differed from scaled BSIPs for each pitching arm segment, 2) calculations for shoulder, but not elbow, kinetics differed between the full DXA-driven and scaled inverse dynamics analyses, and 3) full DXA-driven inverse dynamics calculations for shoulder kinetics were more strongly associated with SMI than with BMI. Results suggest that using participant-specific BSIPs and pitching arm SMIs may improve evidence-based injury prevention guidelines for youth pitchers.

The Application of Medical Imaging on Disabled Athletes in Winter Paralympic Games: A Systematic Review

Purpose: the purpose of this study was to summarize the application and effects of current medical imaging in sports for the disabled, to provide a feasible reference for future imaging medical services and biomechanical modeling for winter Paralympic athletes. Methods: An electronic search was conducted among Google Scholar, ScienceDirect, and Web of Science databases, using the following keywords, “Disability,” “Winter Olympics” and “Medical Imaging.” Inclusion and exclusion criteria were used to screen all identified studies. Of the 374 identified studies, 10 studies were included. Results: Most studies have reported on the application of medical imaging technology in the diagnosis of disability (n =6) and only a few have focused on biomechanical modeling (n = 3) and disability classification (n = 1). However, only 3 studies were involved in winter Paralympic athletes. The results of this study indicate that medical imaging technology can effectively diagnose and prevent the occurrence of injuries in disabled athletes. Conclusion: It is important to use medical imaging to understand the injury mechanism of winter Paralympics athletes and to develop injury prevention strategies. However, only a few studies have focused on the application of medical imaging technology to the winter Paralympic. The results of this study can provide a feasible reference for the medical treatment and training of athletes in the Winter Paralympic Games.

Estimating the Maximum Isometric Force Generating Capacity of Wheelchair Racing Athletes for Simulation Purposes

For the wheelchair racing population, it is uncertain whether musculoskeletal models using the maximum isometric force generating capacity of non-athletic, able-bodied individuals, are appropriate, as few anthropometric parameters for wheelchair athletes are reported in the literature. In this study, a sensitivity analysis was performed in OpenSim, whereby the maximum isometric force generating capacity of muscles was adjusted in 25% increments to literature defined values between scaling factors of 0.25x to 4.0x for two elite athletes, at three speeds representative of race conditions. Convergence of the solution was used to assess the results. Artificially weakening a model presented unrealistic values, and artificially strengthening a model excessively (4.0x) demonstrated physiologically invalid muscle force values. The ideal scaling factors were 1.5x and 1.75x for each of the athletes, respectively, as was assessed through convergence of the solution. This was similar to the relative difference in limb masses between dual energy X-Ray absorptiometry (DXA) data and anthropometric data in the literature (1.49x and 1.70x), suggesting that DXA may be used to estimate the required scaling factors. The reliability of simulations for elite wheelchair racing athletes can be improved by appropriately increasing the maximum isometric force generating capacity of muscles.

Mass distribution of wheelchair athletes assessed using DXA scans and biomechanical simulations

The anthropometries of elite wheelchair racing athletes differ to the generic, able-bodied anthropometries commonly used in computational biomechanical simulations. The impact of using able-bodied parameters on the accuracy of simulations involving wheelchair racing is currently unknown. In this study, athlete-specific mass segment inertial parameters of five elite wheelchair athletes were calculated using dual-energy X-ray absorptiometry scans. These were compared against commonly used anthropometrics parameters of data presented in the literature. A computational biomechanical simulation of wheelchair propulsion assessed the sensitivity of athlete-specific mass parameters using Kruskal-Wallis analysis, Mann-Whitney U analysis and Spearman correlations. Substantial between-athlete body mass distribution variances (thigh mass < 14.6% total body mass), and between-limb asymmetries (<62.4%; 3.1 kg) were observed. Compared to non-athletic able-bodied anthropometric data, wheelchair racing athletes demonstrated greater mass in the upper extremities (up to 3.8% total body mass), and less in the lower extremities (up to 9.8% total body mass). Computational simulations were sensitive to individual body mass distribution, with simulation outputs increasing by up to 12.5% when measured segment masses were 14.3% greater than the generic counterpart. These data suggest non-athletic, able-bodied mass segment inertial parameters are inappropriate for analysing elite wheelchair racing motion.

Inverse Dynamics Modeling of Paralympic Wheelchair Curling

Paralympic wheelchair curling is an adapted version of Olympic curling played by individuals with spinal cord injuries, cerebral palsy, multiple sclerosis, and lower extremity amputations. To the best of the authors' knowledge, there has been no experimental or computational research published regarding the biomechanics of wheelchair curling. Accordingly, the objective of the present research was to quantify the angular joint kinematics and dynamics of a Paralympic wheelchair curler throughout the delivery. The angular joint kinematics of the upper extremity were experimentally measured using an inertial measurement unit system; the translational kinematics of the curling stone were additionally evaluated with optical motion capture. The experimental kinematics were mathematically optimized to satisfy the kinematic constraints of a subject-specific multibody biomechanical model. The optimized kinematics were subsequently used to compute the resultant joint moments via inverse dynamics analysis. The main biomechanical demands throughout the delivery (ie, in terms of both kinematic and dynamic variables) were about the hip and shoulder joints, followed sequentially by the elbow and wrist. The implications of these findings are discussed in relation to wheelchair curling delivery technique, musculoskeletal modeling, and forward dynamic simulations.