Robert O. Andres

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Preferred stride frequency (PSF) of human walking has been shown to be predictable as the resonant frequency of a force-drive harmonic oscillator (FDHO). The purpose of this study was to determine whether walking at the PSF and FDHO leads to minimal metabolic and mechanical costs. Subjects walked on a level treadmill at the PSF, FDHO, and frequencies above(More)
For more than a century the phenomenon of postural sway has attracted the attention of neurologists, control engineers, and otoneurologists, because body sway provides a global assessment of the sensorimotor systems involved in postural control. This article presents an overview of the history of body sway studies, highlighting some of the shortcomings of(More)
Twenty women were asked to generate forces using a dynamometer that were consistent with one of three different work-rest schedules (a low-, medium-, and high-force schedule). Each work-rest schedule consisted of 6 identical blocks of 10 work-rest cycles. Each of the 10 work-rest cycles lasted 1 min. The first work-rest cycle in each block consisted of a(More)
A study was conducted to investigate the effects of a re-usable semirigid ankle orthosis on the support phase of the walking stride in both pre- and post-exercise conditions. Ten young, adult males were required to complete ten trials in each of four orthosis/no orthosis and pre-/post-exercise conditions. Data were collected via a force platform and a high(More)
Five healthy male subjects walked on a control surface (level concrete), and two sloped rock surfaces (walking ballast-rock about 1.9 cm across; main line ballast-rock about 3.8 cm across) while their rearfoot motion (defined throughout as ankle inversion/eversion as seen from the frontal plane) was measured to determine if the different walking surfaces(More)
The loss of a significant portion of a lower extremity causes changes in the usual pattern of human ambulation. These changes have been documented kinematically, kinetically and metabolically, giving insight into the costs of limb amputation relative to ambulatory efforts. The role of the prosthetist is to provide a limb substitute to achieve the best gait(More)
Pushing and pulling during manual material handling can increase the compressive forces on the lumbar disc region while creating high shear forces at the shoe-floor interface. A sagittal plane dynamic model derived from previous biomechanical models was developed to predict L5/S1 compressive force and required coefficients of friction during dynamic cart(More)
Repetitive motion disorders of the upper extremities are the primary cause of lost time in hand-intensive industries. Typical remedies include the introduction of job aids and the redesign of the job. An alternative approach is considered here. Procedures are developed that can be used to determine the parameters of a job (e.g., the rate of work and the(More)
OBJECTIVE This study examined the impact of two common sizes of ballast on gait biomechanics. The terrain was designed to simulate a railroad work setting to investigate the variation in gait kinetics and muscle activation while walking. BACKGROUND Research and epidemiology suggest a potential link between walking surface characteristics and injury.(More)