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The objectives of this study were to assess the within-day and between-day reliability of several center of pressure (COP)-based measures of postural sway and identify whether there were age-related differences in reliability. Thirty-two healthy individuals (16 younger and 16 older) participated. COP was recorded during quiet upright stance on 4 different(More)
Localized muscle fatigue has received growing attention as a potential design variable and exposure metric in research towards prevention of musculoskeletal disorders in the workplace. While fatigue during sustained static work has been investigated extensively, effects during tasks comprising work-rest cycles are less clear. Work-rest models for static(More)
Measurements of human strength can be important during analyses of physical activities. Such measurements have often taken the form of the maximum voluntary torque at a single joint angle and angular velocity. However, the available strength varies substantially with joint position and velocity. When examining dynamic activities, strength measurements(More)
Traditional electromyographic (EMG) measures (e.g., amplitude, mean and median frequencies of the power spectra) have demonstrated inconsistent abilities in monitoring localized muscle fatigue at relatively low effort levels. In the present study, several alternative EMG-based fatigue indices were evaluated, derived using a logarithmic representation of the(More)
Falls from heights resulting from a loss of balance are a major concern in the occupational setting. Previous studies have documented a deleterious effect of lower extremity fatigue on balance. The purpose of this study was to investigate the effect of lumbar extensor fatigue on balance during quiet standing. Additionally, the effects of fatigue rate on(More)
The purpose of this study was to investigate the influence of fatigue time and fatigue level on the increases in postural sway during quiet standing. Centre of pressure-based measures of postural sway were collected both before and after fatiguing participants using three different fatigue levels and two different fatigue times. Results showed increasing(More)
Most existing evidence regarding the effects of age on muscular fatigue has focused on prolonged isometric contractions, repeated maximum dynamic contractions and individuals beyond traditional retirement age (>65 years). In the present study, age-related differences in muscle fatigue during submaximal dynamic efforts were examined. There were 24 younger(More)
UNLABELLED Many workers experience combined physical and mental demands in their jobs, yet the contribution of these demands to the development of musculoskeletal disorders is unclear. The purpose of this study was to investigate muscle- and task-dependent responses to concurrent demands during intermittent static work. Twenty-four participants performed(More)
The use of electromyographic measures, in concert with modeled or empirical representations of muscle physiology, is a common approach for estimation of muscle force. Existing models of the lumbar musculature have allowed model parameters to vary for an individual subject. While this approach improves apparent predictive ability, it loses some degree of(More)
In this study, the main and interactive effects of obesity and age on functional performance were assessed during intermittent exertions involving the upper extremity. The prevalence of obesity has doubled over the past 30 years and this increase is associated with higher health care costs, rates of workplace injury, and lost workdays. Obesity and aging can(More)