Peak ankle moment and power generation during the push-off phase of human walking contribute to leg swing initiation and forward acceleration of the body’s center of mass, thereby playing a pivotal role in regulating step lengths and walking speeds. 1 Unfortunately, aging and many gait pathologies
Katie A. Conway, Randall G. Bissette and Jason R. Franz
Edited by Mark Latash
It is suggested that the famous problem of motor redundancy is inapplicable to human voluntary movements. Such notions as “the elimination of biomechanical degrees of freedom” should not be used in human movement studies. During natural movements, elements within apparently redundant sets are all involved in solving motor tasks. The abundance of elements is a keystone forming the foundation of motor synergies. It allows natural movements to display both flexibility and stability.
Joel A. Vilensky and Brian L. O'Connor
In this paper we review the literature on stepping in nonhuman and human primates with complete transection of the spinal cord and consider these data relative to the principle of “encephalization” of motor functions with ascension in phylogeny. We conclude that techniques useful for producing self-generated stepping behavior in nonprimates with complete spinal cord transection may not be successful in humans and other higher primates with complete transection.
Yuhei Inoue, Jose M. Plehn-Dujowich, Aubrey Kent and Steve Swanson
Despite the escalation of football coaches’ salaries at National Collegiate Athletic Association (NCAA) Football Bowl Subdivision (FBS) institutions, little empirical investigation has been undertaken to identify the determinants of their compensation. As such, the purpose of this study is to explain how the level of coaching compensation is determined based on three theoretical perspectives in managerial compensation: marginal productivity theory, human capital theory, and managerialism. The analysis of compensation data of head football coaches at FBS institutions in 2006–2007 shows that the maximum total compensation of these coaches increases with their past performance. The results further reveal that coaches with greater human capital tend to receive a compensation package where bonuses account for a smaller proportion of the maximum total compensation. Overall, these findings mostly confirm the predictions drawn from managerial productivity theory, human capital theory and managerialism.
Paul G. Taylor, Michael Small, Kwee-Yum Lee, Raul Landeo, Damien M. O’Meara and Emma L. Millett
Entropy is an effective tool for investigation of human movement variability. However, before applying entropy, it can be beneficial to employ analyses to confirm that observed data are not solely the result of stochastic processes. This can be achieved by contrasting observed data with that produced using surrogate methods. Unlike continuous movement, no appropriate method has been applied to discrete human movement. This article proposes a novel surrogate method for discrete movement data, outlining the processes for determining its critical values. The proposed technique reliably generated surrogates for discrete joint angle time series, destroying fine-scale dynamics of the observed signal, while maintaining macro structural characteristics. Comparison of entropy estimates indicated observed signals had greater regularity than surrogates and were not only the result of stochastic but also deterministic processes. The proposed surrogate method is both a valid and reliable technique to investigate determinism in other discrete human movement time series.
Human performance enhancement is one of kinesiology’s many vibrant topics for inquiry. Though philosophers in kinesiology departments have offered some contribution to this topic, this paper argues that philosophers could improve their relevance by better engaging the existing scientific research. Rather than simply defending their place at the table, this paper proposes that philosophers build upon existing contributions to the ethics of human enhancement by increasing their scientific literacy. At the same time, this paper argues that certain patterns in philosophical discussions of human enhancement do not connect with scientific researchers. The paper concludes that ultimately philosophers must become more conversant with the language of science if they are going to continue contributing to central questions within the field of kinesiology.
Heon-Jeong Kim and Bernard J. Martin
Simulation of human movements is an essential component for proactive ergonomic analysis and biomechanical model development (Chaffin, 2001). Most studies on reach kinematics have described human movements in a static environment, however the models derived from these studies cannot be applied to the analysis of human reach movements in vibratory environments such as in-vehicle operations. This study analyzes three-dimensional joint kinematics of the upper extremity in reach movements performed in static and specific vibratory conditions and investigates vibration transmission to shoulder, elbow, and hand along the body path during pointing tasks. Thirteen seated subjects performed reach movements to five target directions distributed in their right hemisphere. The results show similarities in the characteristics of movement patterns and reach trajectories of upper body segments for static and dynamic environments. In addition, vibration transmission through upper body segments is affected by vibration frequency, direction, and location of the target to be reached. Similarities in the pattern of movement trajectories revealed by filtering vibration-induced oscillations indicate that coordination strategy may not be drastically different in static and vibratory environments. This finding may facilitate the development of active biodynamic models to predict human performance and behavior under whole body vibration exposure.
Fabien Cignetti, Sébastien Caudron, Marianne Vaugoyeau and Christine Assaiante
There is evidence that adolescence is a critical period in development, most likely involving important modifications of the body schema and of the sensorimotor representations. The present study addressed this issue, by investigating the differences between adolescents and adults regarding the integration of proprioceptive information at both perceptual and postural levels and the visual recognition of human movement. Proprioceptive integration was examined using muscle-tendon vibration that evoked either a postural response or an illusory sensation of movement. The ability to recognize human movement was investigated from a paradigm where the participants had to discern between human movements performed with and without gravity. The study produced three main findings. First, the adolescents had larger postural responses to tendon vibrations than the adults, with visual information enabling them to reduce this exaggerated postural reaction. Second, the adolescents had a greater illusory perception of movement compared with the adults. Third, the adolescents had the same perceptual ability as adults in the human movement perception task. In conclusion, we were able to highlight notable differences between adolescents and young adults, which confirms the late maturation of multisensory integration for postural control and the privileged visual contribution to postural control.
Li-Xin Guo, Zhao-Wen Wang, Yi-Min Zhang, Kim-Kheng Lee, Ee-Chon Teo, He Li and Bang-Chun Wen
The aim of this study is to investigate the effect of material property changes in the spinal components on the resonant frequency characteristics of the human spine. Several investigations have reported the material property sensitivity of human spine under static loading conditions, but less research has been devoted to the material property sensitivity of spinal biomechanical characteristics under a vibration environment. A detailed three-dimensional finite element model of the human spine, T12– pelvis, was built and used to predict the influence of material property variation on the resonant frequencies of the human spine. The simulation results reveal that material properties of spinal components have obvious influences on the dynamic characteristics of the spine. The annulus ground substance is the dominant component affecting the vertical resonant frequencies of the spine. The percentage change of the resonant frequency relative to the basic condition was more than 20% if Young’s modulus of disc annulus is less than 1.5 MPa. The vertical resonant frequency may also decrease if Poisson’s ratio of nucleus pulposus of intervertebral disc decreases.
John H. Challis
Segmental moment of inertia values, which are often required to perform mechanical analyses of human movement, are commonly computed using statistical models based on cadaver data. Two sets of equations for estimating human limb moments of inertia were evaluated: linear multivariable equations and nonlinear equations. Equation coefficients for both sets of equations were determined using the cadaver data of Chandler et al. (1975). A cross-validation procedure was used to circumvent the problem of model evaluation when there is limited data with which to develop and evaluate the model. Moment of inertia values for the longitudinal axes were predicted with similar degrees of accuracy with either set of equations, while for the transverse axes the nonlinear equations were superior. An evaluation of the influence of the accuracy of moment of inertia estimates on resultant joint moments for three activities showed that the influence of these errors was generally small.