Acute effects of localized muscle fatigue on postural control and patterns of recovery during upright stance: influence of fatigue location and age.

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.