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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.

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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.

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John Gleaves

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.

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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.

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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.

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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.

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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.

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Toshimasa Yanai and James G. Hay

The purpose of this study was to test the hypothesis that, in human running at a given speed, runners select the combination of cycle rate (CR) and cycle length (CL) that minimizes the power generated by the muscles. A 2-D model of a runner consisting of a trunk and two legs was defined. A force actuator controlled the length of each leg, and a torque actuator controlled the amplitude and frequency of the backward and forward swing of each leg. The sum of the powers generated by the actuators was determined for a range of CRs at each of a series of speeds. The CR and CL vs. speed relationships selected for the model were derived from a series of CR and CL combinations that required the least power at each speed. Two constraints were imposed: the maximum amplitude of the forward and backward swing of the legs (±50°) and the minimum ground contact time needed to maintain steady-state running (0.12 sec). The CR vs. speed and CL vs. speed relationships derived on the basis of a minimum power strategy showed a pattern similar to those reported for longitudinal (within-subjects) analyses of human running. The anatomical constraint set a limit on the maximum CL attainable at a given speed, and the temporal constraint made CL decrease at high speeds. It was concluded that the process for selecting CL-CR combinations for human running has characteristics similar to the process for solving a constrained optimization problem.

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Jacob Buus Andersen and Thomas Sinkjaer

Due to the complexity of applying a well-defined stretch during human walking, most of our knowledge about the short latency stretch reflex modulation in humans is based on H-reflex studies. To illuminate the difference between the two methodologies, both types of reflexes were evoked in the same subjects, same experiment. Stretch reflexes were evoked via a stretch device capable of evoking stretch reflexes of the human soleus muscle during walking. H-reflexes were elicited by an electrical stimulation of the tibial nerve at the popliteal fossa at the knee. A significantly different modulation of the two reflexes was found in the late stance where the stretch reflex decreased in relation to the H-reflex. This was consistent with an unloading of the muscle spindles during the push-off in late stance, suggesting a complex alpha-gamma coactivation, if any, at this time of the step. The soleus stretch reflex and H-reflex were compared during the stance phase of walking and sitting at matched soleus EMG activity. No difference was found in the amplitude of the stretch reflex. However, there was a significant decrease of the H-reflex during the stance phase of walking, consistent with a task-specific presynaptic mediated reflex control. It is proposed that the short latency stretch reflex during walking is not sensitive to such a presynaptic inhibition.

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Jürgen Konczak, Kai Brommann and Karl Theodor Kalveram

Knowledge of how stiffness, damping, and the equilibrium position of specific limbs change during voluntary motion is important for understanding basic strategies of neuromotor control. Presented here is an algorithm for identifying time-dependent changes in joint stiffness, damping, and equilibrium position of the human forearm. The procedure requires data from only a single trial. The method relies neither on an analysis of the resonant frequency of the arm nor on the presence of an external bias force. Its validity was tested with a simulated forward model of the human forearm. Using the parameter estimations as forward model input, the angular kinematics (model output) were reconstructed and compared to the empirically measured data. Identification of mechanical impedance is based on a least-squares solution of the model equation. As a regularization technique and to improve the temporal resolution of the identification process, a moving temporal window with a variable width was imposed. The method's performance was tested by (a) identifying a priori known hypothetical time-series of stiffness, damping, and equilibrium position, and (b) determining impedance parameters from recorded single-joint forearm movements during a hold and a goal-directed movement task. The method reliably reconstructed the original angular kinematics of the artificial and human data with an average positional error of less than 0.05 rad for movement amplitudes of up to 0.9 rad, and did not yield hypermetric trajectories like previous procedures not accounting for damping.