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The purposes of this study were to investigate the effects of fatigue location and age on changes in postural control induced by localized muscle fatigue, as well as the patterns of recovery post-fatigue. Groups of 16 younger (18-25 years) and 16 older (55-65 years) participants performed submaximal isotonic fatiguing exercises involving the unilateral ankle plantar flexors, knee extensors, and shoulder flexors, and bilateral lumbar extensors. Postural control was assessed during quiet upright stance, from center-of-pressure and center-of-mass time series obtained before and after the fatiguing exercises. Acute effects of fatigue differed between joints, with the most substantial effects evident at the lower back, followed by the ankle. Neither knee nor shoulder fatigue resulted in significant effects on postural control. Significant acute effects of fatigue were found only among the younger group. Recovery of postural control post-fatigue was influenced by age, being more rapid in the younger group, but not by fatigue location. Along with existing evidence, these results may facilitate the development of strategies to prevent occupational falls.

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Measures of human sway during upright standing are frequently used as indirect measures of the postural control system. The objective of this study was to assess the reliability of several center-of-pressure-based sway measures. Test-retest reliability was determined both within-days (under different visual and surface conditions) and between-days (5 different days). Intraclass Correlation Coefficient (ICC), Standard Error of Measurement (SEM), Minimal Metrically Detectable Change (MMDC), and Coefficient of Variation (CV) were used as reliability indices. Mean velocity was found to be the most reliable measure among those evaluated. Overall, between-day reliability indices were better than within-day reliability. When subjects were standing on a compliant surface, several measures exhibited better reliability under ‘eyes open’ condition. These results can be useful in guiding the selection of postural sway measures and appropriate number of replications to improve sway assessment.

We examined the effects of three control strategies on postural control in the presence of muscle fatigue induced by a simulated occupational task. The findings can facilitate the development of future strategies or practical interventions to reduce falling risk and prevent falls.

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Localized muscle fatigue has been demonstrated to compromise postural control, yet potential differential effects of the site of fatigue have not been determined. In this study, the effects of short-term induced fatigue in four muscle groups (shoulder, torso, knee, and ankle) on standing sway were determined. Sixteen young participants were required to perform fatiguing sub-maximal isotonic exercises. Postural sway was recorded using a force plate before and after the exercises. Fatigue induced at the ankle and torso was found to have largest adverse effects on postural control. These results have implications for the control of fatigue-related falls and the design of future experiments.