Background: During postural control, older adults are more dependent on proprioception than are young adults. Ankle proprioception, which plays an important role in maintaining postural balance, decreases with age. Published studies are insufficient to establish a significant age difference in postural sway resulting from the known age-related decrease in ankle proprioception and do not examine various detailed test conditions.Objects: The present study aimed to compare ankle proprioception between older and younger groups along dimensions of position vs. force proprioception and dorsiflexion vs. plantarflexion. The present study also aimed to compare postural sway between young and older women during quiet standing under two sensory conditions. Methods:We recruited seven young women aged 21-24 and seven older women aged 60-63. Ankle proprioception was assessed as the accuracy of the joint position sense (JPS) and the force sense (FS). Postural sway was assessed using center-of-pressure measurements recorded during quiet standing under two sensory positions: eyes open and eyes closed with head tilted back.Results: Older women had lower JPS in dorsiflexion and lower FS in plantarflexion than did younger women. We found no significant age differences in JPS in plantarflexion or in FS in dorsiflexion. We observed a main effect of group on postural sway in two sway parameters out of three. We observed significant differences in JPS with dorsiflexion, and in FS with plantarflexion. Conclusion:Proprioception for ankle plantar flexor decreased more significantly with aging than did that for ankle dorsiflexor, accounting for the impaired postural balance observed in older women.

Background: Older adults use different ankle muscle activation patterns during difficult static balance conditions. It has been suggested that this is related to a decline in proprioception with age, resulting in reduced postural balance. However, the association between proprioception and ankle muscle activity during quiet standing has not been directly assessed.Objects: This study aimed to investigate the effects of age and sensory condition on ankle muscle activity and the association between ankle proprioception and ankle muscle activity. Methods:We recruited 10 young women and 9 older women. Ankle proprioception was evaluated using joint position sense (JPS) and force sense (FS) divided by dorsiflexion and plantarflexion. The electromyographic activity of the tibialis anterior (TA) and gastrocnemius (GCM) muscles was collected during quiet standing.Results: Older women activated GCM muscle more than young during quiet standing and when performing difficult tasks. Older women had more errors in JPS dorsiflexion and FS plantarflexion than did young. The GCM muscle activity is related to JPS dorsiflexion and FS plantarflexion. Conclusion:Lower proprioception of the GCM with age leads to increased muscle activity, resulting in reduced postural balance. There was no difference in TA proprioception or muscle activity among older women with frequent physical activity. Laughton et al. [14] found an association between postural balance and plantar flexor muscle activity in older adults who are vulnerable to falls. Benjuya et al. [13] found that older adults demonstrated significantly higher levels of ankle muscle activ-