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Joseph B. Lesnak, Dillon T. Anderson, Brooke E. Farmer, Dimitrios Katsavelis and Terry L. Grindstaff

different testing methods was determined using a Pearson product–moment correlation coefficient. Linear regression was used to develop a prediction equation, and Bland–Altman plots with limits of agreement calculations were used to validate the prediction equation. The sample was randomly divided evenly

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Robert K. Jensen, Tina Treitz and Han Sun

The purpose of the study was to use the elliptical cylinder model adapted for infants (Sun & Jensen, 1994) with a cross-sectional sample to select appropriate multiple linear regression equations for predicting masses and nonlinear regression equations for predicting principal moments of inertia (Yeadon & Morlock, 1989). The linear and nonlinear predictions were evaluated with an independent cross-validation sample of infants and a sample where inertias ranged below and above the cross-sectional sample. The cross-validation for masses was compared to a cross-validation of four linear regressions for masses developed by Schneider and Zernicke (1992). It is recommended that the linear regression equations developed in this study be used to predict infant segment masses. It is also recommended that the nonlinear regression equations developed in this study be used to predict the principal moments of inertia of all infant segments, other than head Ix and lower trunk Ix and Iy.

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Robert K. Jensen and Paula Fletcher

The segment principal moments of inertia of a sample of 7 elderly males and 12 elderly females were estimated using a model based on stacked elliptical cylinders at 2-cm intervals. Apart from the thigh, all male parameters were larger than female parameters. The largest differences were for the lower trunk and hand and for the forearm. The inertia parameters of the thigh for the males were about 12% smaller than the females. Nonlinear estimations of segment principal moments were then determined. The effect of the differences was tested by cross validating cadaver results against the elliptical model results. The regressions were then cross validated using an independent sample of 6 subjects. The standard errors of fit given as a percentage of the mean, Sf, were smaller than the cross validation results for the cadaver regressions and the differences were attributed to differences between cadavers and living subjects.

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Kai-Yu Ho, Brenda Benson Deaver, Tyrel Nelson and Catherine Turner

that typically has a lower camera sampling frequency than other computer-based 2D motion analysis. As individuals with ACLR may exhibit more knee valgus 2 and there is limited data regarding the reliability/validity of using MAA to measure knee movement, it is necessary for validation of using a MAA

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Sergio Jiménez-Rubio, Archit Navandar, Jesús Rivilla-García, Víctor Paredes-Hernández and Miguel-Ángel Gómez-Ruano

can help interpret the actual physical exertion of the player and give meaningful information about the adequacy of workloads in training and competition. Different authors have validated RTP criteria following hamstring strain injuries, 21 but no one has used performance parameters from competition

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Monna Arvinen-Barrow, Nathan Maresh and Jennifer Earl-Boehm

.1136/bjsports-2012-091203 23064083 21. Glazer DD . Development and preliminary validation and the Injury-Psychological Readiness to Return to Sport (I-PRRS) scale . J Athl Train . 2009 ; 44 : 185 – 189 . PubMed ID: 19295964 doi:10.4085/1062-6050-44.2.185 10.4085/1062-6050-44.2.185 19295964 22. Brewer BW

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Wei Liu, Jill Whitall and Thomas M. Kepple

Functional arm reaching involves multilinked joints: shoulder, elbow, and wrist. We propose that induced position analysis is a useful analytical tool for multijoint coordination of arm reaching. This method was used to compute the contributions of the net joint moment to the hand position when reaching forward. We describe the method and give examples of validating this model with motion capture data. The shoulder and elbow were prime movers of the arm: both acted together with an “overshoot” and “undershoot” pattern respectively to move the hand forward into the final position.

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David Werner, John Willson, Richard Willy and Joaquin Barrios

Frontal plane knee alignment can influence the development and management of various knee pathologies. Valid and reliable clinical methods for assessment are needed. The primary purposes of this study were to assess the validity and reliability of inclinometer-based frontal plane tibial orientation as a limb alignment measure, and secondarily to establish normal values in healthy individuals. Frontal tibial orientation was validated per moderately strong correlation to radiographic knee alignment. Intra- and interrater reliability were excellent. The normative mean was approximately 7°. In summary, inclinometer-based frontal tibial orientation is a valid and reliable clinical measure of frontal plane knee alignment.

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Shawn S. Kao, Richard W. Sellens and Joan M. Stevenson

A wind tunnel test was conducted to empirically determine the relationship between the Magnus force (M), spin rate (ω), and linear velocity (V) of a spiked volleyball. This relationship was applied in a two-dimensional mathematical model for the trajectory of the spiked volleyball. After being validated mathematically and empirically, the model was used to analyze three facets of play that a coach must address: the importance of topspin, possibility of overblock spiking, and optimum spiking points. It was found that topspin can increase the spiking effectiveness dramatically in many ways. It was also found that a shot spiked from about 2 m behind the net has the least possibility of being blocked.

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Thomas D. Brown

Numerical approximation of the solutions to continuum mechanics boundary value problems, by means of finite element analysis, has proven to be of incalculable benefit to the field of musculoskeletal biomechanics. This article briefly outlines the conceptual basis of finite element analysis and discusses a number of the key technical considerations involved, specifically from the standpoint of effective modeling of musculoskeletal structures. The process of conceiving, developing, validating, parametrically exercising, and interpreting the results of musculoskeletal finite element models is described. Pertinent case study examples are presented from two series of finite element models, one involving total hip implant dislocation and the other involving femoral head osteonecrosis.