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Pirjo Kejonen, Kari Kauranen, Ahti Niinimaa and Heikki Vanharanta

Context:

Balance evaluation and training are typically included in rehabilitation after sport injuries.

Objective:

To evaluate and compare the maximal velocities and accelerations of balancing movements during 2-leg stance with eyes open and closed. The effect of age on the measured values was also evaluated.

Design:

Cross-sectional study.

Participants:

100 healthy, randomly selected subjects (50 men, 50 women; age 31–80 years).

Setting:

Body-movement values were measured with the Mac Reflex motion-analysis system.

Intervention:

Subjects stood barefoot.

Main Outcome Measures:

ANOVAs were used to explain the body movements. The location of measurement, presence or absence of vision, and subjects’ age and gender were used as explanatory variables.

Results:

With eyes closed, all measured body parts had significantly higher maximal velocity and acceleration values than with eyes open. Age seemed to affect the acceleration values.

Conclusion:

Visual information was found to significantly influence movement values. Exercises should be done under various conditions to improve standing balance abilities.

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Rebecca Avrin Zifchock, Kristamarie Pratt, Allison Brown and Howard Hillstrom

The purpose of this study was to compare the magnitude of knee kinematic coupling between genders and among open- and closed-chain tasks. A secondary purpose was to compare the consistency of knee kinematic coupling between genders and among open- and closed-chain tasks. Vector-coding methods were used to quantify coupling in the sagittal and transverse planes of the knee between full extension and 20 degrees of flexion as 10 males and 10 females walked, ascended and descended stairs, and performed a passive pendulum leg drop. An ANOVA showed no main effect of gender. There was a main effect of task, where coupling during the stance phase of walking was significantly greater than each of the other tasks. Intraclass correlation values suggested that males were slightly more consistent than females. A general lack of divergence between genders may be related to the tasks analyzed in this study. It is possible that more strenuous tasks may elicit larger differences.

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Vanessa R. Yingling, H. John Yack and Scott C. White

This study investigated whether rearfoot motion at heel contact during running attenuates the magnitude of the impact force traveling through the body. Fifteen subjects completed running trials for two conditions:(a) running on a treadmill at a self-selected speed and a cadence of 160 steps/min and (b) running at the same speed and cadence but with rearfoot motion limited by a medial wedge inserted into the subject's shoe. A paired t test was used to test for differences between conditions in the peak accelerations of each accelerometer and the time to peak of the tibia acceleration. The predominant impact frequency and amplitude of the frequency peak were also tested for significant differences. No significant difference was found in the variables compared between the two conditions. The results demonstrated that restriction of rearfoot motion using a medial wedge during the initial 15% of the stance phase has no effect on the characteristics of the impulse wave at the tibia.

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Robert N. Marshall, David J. Paterson and Paul Glendining

Approximately 25 runners were filmed at the 24.9- and 41.0-km points in the 1987 Everest Marathon. Their finishing times ranged from 4:53:10 to 7:14:37. Leg length, step lengths, step frequencies, knee angles at impact, and ankle-to-hip angles at impact were determined for each runner who appeared in both films (N = 20). The slopes at the two filming sites were −21.8% and −26.8%, considerably steeper gradients than have previously been studied. When compared to data from other downhill running studies at −10% gradient, these athletes had slightly slower speeds, shorter step lengths, straighter legs on impact, and greater minimum knee angles during stance. The results suggest that the runners used a variety of techniques to minimize the effects of ground impact while still allowing for the competitive aspect of the race, considerable variation in footing and terrain, and personal safety.

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Garry D. Wheeler

The biological area of adapted physical activity research has traditionally been dominated by the positivist or rational empirical paradigm, or the scientific method. Underlying assumptions of the inquirer and inquired’s objectivity and independence have generated much criticism. Researchers have argued that the scientific method produces an impoverished view of reality and that claims to an objective and value-free stance are ideological and mythical. Critique of rational-empiricism, the scientific method, present science, or the received-view may be understood at three levels: intraparadigmatic, extraparadigmatic, and intramethod. Dr. Shephard (1998) addresses the latter in his paper and as such, his is a method-based approach. A methodological analysis, however, requires examining the underlying tacit assumptions of the scientific method. In this paper, critique of the scientific method is offered and justification of the critique examined. Proposed alternatives include an expansionist view of research, inclusion of subjective elements, triangulated designs, and empowerment of subjects.

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Ana M. F. Barela, José A. Barela, Natália M. Rinaldi and Diana R. de Toledo

This study examined the influence of both optic flow characteristics and intention on postural control responses. Two groups of 10 adults each were exposed to the room’s movement either at 0.6 cm/s (low velocity group) or 1.0 cm/s (high velocity group). All the participants stood in the upright stance inside of a moving room and were informed about the room movement only after the fourth trial as they were asked to resist to its influence. Results revealed that participants from both groups were influenced by the imposed visual stimulus in the first trials, but the coupling strength was weaker for the high velocity group. The request to resist the visual influences decreased visual influences on body sway, but only for the low velocity group. These results indicate that intention might play a role in stimulus influences on body sway but it is stimulus dependent.

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Pamela C. Allison, Becky W. Pissanos, Adrian P. Turner and Denise R. Law

The constructivist theoretical tenet, that individuals create meaning based on the interaction of their previous knowledge and beliefs with currently experienced phenomena, served as the orientating framework for inquiry into a physical education teacher education program that emphasizes development of skillful movers as the primary goal of physical education. Epistemological stances on movement skillfullness held by 25 beginning preservice teachers were explored. Data were collected in a directed reflective format. Inductive data analysis revealed that these preservice teachers see above average ability, task commitment, and creativity as characteristic of being skillful. Their constructs of skillfulness were developed in contexts that include the human body in action, intermesh of movements, whole pattern of performance, presence of movement, the sociocultural event, and skillfulness as a backdrop for teaching. These findings informed the dialectic between teacher education faculty and students by creating avenues for shared understandings of the epistemological bases of the program.

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Jessie M. Huisinga, Kendra K. Schmid, Mary L. Filipi and Nicholas Stergiou

Patients with multiple sclerosis (MS) experience abnormal gait patterns and reduced physical activity. The purpose of this study was to determine if an elliptical exercise intervention for patients with MS would change joint kinetics during gait toward healthy control values. Gait analysis was performed on patients with MS (n = 24) before and after completion of 15 sessions of supervised exercise. Joint torques and powers were calculated, while also using walking velocity as a covariate, to determine the effects of elliptical exercise on lower extremity joint kinetics during gait. Results show that elliptical exercise significantly altered joint torques at the ankle and hip and joint powers at the ankle during stance. The change in joint power at the ankle indicates that, after training, patients with MS employed a walking strategy that is more similar to that of healthy young adults. These results support the use of elliptical exercise as a gait training tool for patients with MS.

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Valérie Michel-Pellegrino, David Hewson, Jean-Yves Hogrel and Jacques Duchêne

The aim of this study was to analyze differences in biomechanical parameters between elderly and control participants when stepping up, to evaluate control of balance. Eleven control and 14 elderly participants performed a step from an initial static posture onto a 7-cm-high force plate. For the spontaneous-velocity condition, elderly participants performed a slower progression velocity than control participants. Elderly participants spent proportionally more time in stance phase, with a corresponding decrease in swing phase, than the control participants, irrespective of movement velocity. In contrast, at spontaneous velocity the parameters related to ground-reaction force (GRF) showed that anteroposterior and mediolateral forces at toe-off of the support limb and the slope of vertical force during weight transfer were significantly smaller for the elderly than for control participants. These GRF parameters depended on the stepping-up velocity. The elderly develop a spatiotemporal strategy and reduced movement velocity to control support balance.

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Raviraj Nataraj, Musa L. Audu, Robert F. Kirsch and Ronald J. Triolo

This pilot study investigated the potential of using trunk acceleration feedback control of center of pressure (COP) against postural disturbances with a standing neuroprosthesis following paralysis. Artificial neural networks (ANNs) were trained to use three-dimensional trunk acceleration as input to predict changes in COP for able-bodied subjects undergoing perturbations during bipedal stance. Correlation coefficients between ANN predictions and actual COP ranged from 0.67 to 0.77. An ANN trained across all subject-normalized data was used to drive feedback control of ankle muscle excitation levels for a computer model representing a standing neuroprosthesis user. Feedback control reduced average upper-body loading during perturbation onset and recovery by 42% and peak loading fby 29% compared with optimal, constant excitation.