one trait and the whole organism ( Calder, 1982 ). Phylogenetic scaling examines the size relationships of organisms among various species, potentially extant and extinct species (e.g., chicken and Tyrannosaurus: Hutchinson & Garcia, 2002 ). The focus of this paper is to examine how geometric scaling
John H. Challis
Samantha L. Winter, Sarah M. Forrest, Joanne Wallace, and John H. Challis
accelerations, such as throwing or kicking. 1 , 2 Even during the swing-phase of gait, significant differences in resultant joint moments have been calculated as a result of using different methods of estimating the BSIPs of the thigh segment. 1 Geometric models are a cost-effective way of estimating subject
Jason Wicke and Genevieve A. Dumas
The geometric method combines a volume and a density function to estimate body segment parameters and has the best opportunity for developing the most accurate models. In the trunk, there are many different tissues that greatly differ in density (e.g., bone versus lung). Thus, the density function for the trunk must be particularly sensitive to capture this diversity, such that accurate inertial estimates are possible. Three different models were used to test this hypothesis by estimating trunk inertial parameters of 25 female and 24 male college-aged participants. The outcome of this study indicates that the inertial estimates for the upper and lower trunk are most sensitive to the volume function and not very sensitive to the density function. Although it appears that the uniform density function has a greater influence on inertial estimates in the lower trunk region than in the upper trunk region, this is likely due to the (overestimated) density value used. When geometric models are used to estimate body segment parameters, care must be taken in choosing a model that can accurately estimate segment volumes. Researchers wanting to develop accurate geometric models should focus on the volume function, especially in unique populations (e.g., pregnant or obese individuals).
Matthew A. Kilgas, Scott N. Drum, Randall L. Jensen, Kevin C. Phillips, and Phillip B. Watts
Rock climbers believe chalk dries the hands of sweat and improves the static coefficient of friction between the hands and the surface of the rock. The purpose of this study was to assess whether chalk affects geometric entropy or muscular activity during rock climbing. Nineteen experienced recreational rock climbers (13 males, 6 females; 173.5 ± 7.0 cm; 67.5 ± 3.4 kg) completed 2 climbing trails with and without chalk. The body position of the climber and muscular activity of the finger flexors was recorded throughout the trial. Following the movement sequence participants hung from a standard climbing hold until they slipped from the climbing structure, while the coefficient of friction and the ratio of the vertical forces on the hands and feet were determined. Although there were no differences in the coefficient of friction (P = .748), geometric entropy (P = .359), the ratio of the vertical forces between the hands and feet (P = .570), or muscular activity (P = .968), participants were able to hang longer after the use of chalk 62.9 ± 36.7 s and 49.3 ± 25.2 s (P = .046). This is advantageous because it may allow for prolonged rests, and more time to plan the next series of climbing moves.
Claire Waldock, Nick Milne, Jonas Rubenson, and Cyril Jon Donnelly
This study attempts to apply geometric morphometric techniques for the analysis of 3D kinematic marker-based gait data. As a test, we attempted to identify sexual dimorphism during the stance phase of the gait cycle. Two techniques were used to try to identify differences in the way males and females walk without the results being affected by individual differences in body shape and size. Twenty-eight kinematic markers were placed on the torso and legs of 6 male and 8 female subjects, and the 3D time varying coordinates of the kinematic markers were recorded. The gait cycle trials were time-normalized to 61 frames representing the stance phase of gait, and the change in the shape of the configuration of kinematic markers was analyzed using principal components analysis to produce ‘gait signatures’ that characterize the kinematics of each individual. The variation in the gait signatures was analyzed with a further principal components analysis. These methods were able to detect significant sexual dimorphism even after the effects of sexual body shape and size differences were factored out. We discuss insights gained from performing this study which may be of value to others attempting to apply geometric morphometric methods to motion analysis.
Alan Barr and David Hawkins
An anatomical database was constructed containing three-dimensional geometric representations of the structures comprising the lower extremity. The database was constructed by digitizing 100 high-resolution digital photographic images supplied from the National Library of Medicine’s Visual Human Male (VHM) project. These images were taken of sequential transverse cross-sectional slices of the leg. Slices were located 1 cm apart between a location approximately 3 mm below the superior aspect of the ilium and approximately 2 mm below the distal end of the fibula. Image Tool Software (v. 2.0) was used to manually digitize the perimeters of muscles, tendons, and bones of the pelvis, thigh, and shank from the right leg of the VHM. Additionally, the perimeter of the leg and the inner aspect of the superficial fat layer were digitized. The pelvis was digitized as a hemi-pelvis. Tissue perimeters were characterized using between 10 and 151 nodes within each slice; the number of nodes varied depending on the tissue’s size. Transverse cross-sectional slice number, structure identification, node number, and the two-dimensional coordinates of each node were stored in a data file. The information contained in this file is unique and provides a database that researchers can use to investigate questions related to tissue anatomy and movement mechanics that cannot be considered using existing musculoskeletal data sets.
John W. Chow, Warren G. Darling, and James C. Ehrhardt
The purpose of this study was to determine the coordinates of the origin and insertion, muscle volumes, lengths, lines of action, and effective moment arm of the quadriceps muscles in vivo using magnetic resonance imaging (MRI) and radiography for a pilot study involving musculoskeletal modeling. Two magnetic resonance scans were performed, and axial images were obtained for the left thigh of a female subject in the anatomical position to measure muscle volume, coordinates of the origin and insertion, and muscle belly length at the anatomical position of each quadriceps muscle. Six knee radiographs were used to determine the effective moment arm of the quadriceps force at different knee flexion angles. A combination of MRI and radiography data was used to compute the muscle lengths at different knee flexion angles. The coordinates of the vastus lateralis, muscle volumes of individual quadriceps muscles, and effective moment arms were clearly different from the corresponding values from cadaver data reported in the literature. These comparisons demonstrate the advantages of using personalized muscle parameters instead of those collected from cadavers and dry-bone specimens.
Nicola Taylor, David Giles, Micha Panáčková, James Mitchell, Joel Chidley, and Nick Draper
movement and tactical components are not part of such measures. The same is also true with the application of time–motion analysis 13 , 14 and indices of the fluency of the displacement of climbers’ center of mass, such as the geometric index of entropy. 15 , 16 As a result, to gain further insight into
Danny M. Pincivero, Rachael R. Polen, and Brittany N. Byrd
force production and estimates of arm volume. This approach of the present investigation focused on the following 2 major considerations: (1) that the relationship between the aforementioned variables need not be linear and (2) can a reasonable geometric representation of the limb housing the active
Mika R. Moran, Perla Werner, Israel Doron, Neta HaGani, Yael Benvenisti, Abby C. King, Sandra J. Winter, Jylana L. Sheats, Randi Garber, Hadas Motro, and Shlomit Ergon
environmental measures of the walking routes that the residents chose. Two types of environmental measures were examined: geometrical attributes and streetscape variables. Geometrical attributes included the route length (in meters) and slope (in degrees). The route slopes were calculated within a 2-m buffer