Percentage of decline in individual proprioceptors in older adults

[Purpose] Although standing balance and functions of each proprioceptor decline with age in older adults, data regarding the types and percentages of proprioceptors susceptible to decline are unavailable. In this study, we investigated the rate of decline in each proprioceptor area in older adults and also the effect of aging on the association between postural balance and proprioception. [Participants and Methods] This study performed between November 2012 and July 2022 included both young and older adults. Vibration stimuli were applied to the gastrocnemius and lumbar multifidus muscles at 30-250 Hz to assess the effects of the easily attenuated proprioceptors. The independent t-test showed a decline in proprioception in older adults. A χ² test was performed to determine proprioceptors that were susceptible to attenuation in older adults. [Results] The results revealed that many older adults had reduced muscle spindles (low and high frequencies) in their lower legs and trunk (low frequency). [Conclusion] Proprioceptive ability is lower in older adults than in younger individuals. Therefore, activation programs to treat the reduced intrinsic receptive responsiveness may be required for rehabilitation of older adults.