Assessing age-related proprioceptive changes through active and passive tasks: implications for stroke assessment

<i>Objective.</i>Voluntary control of motor actions requires precise regulation of proprioceptive and somatosensory functions. While aging is known to impair sensory processing, its effect on proprioception remains unclear. Previous studies report conflicting findings on whether passive proprioception (i.e. during externally driven movements) declines with age, and research on age-related changes in active proprioception (i.e. during voluntary movements) remains limited, particularly in the upper limb. Understanding these changes is critical for identifying and preventing impairments that may affect movement performance and mobility, particularly in neurological conditions such as stroke or Parkinson's disease.<i>Approach.</i>We refined a robotic protocol to assess upper-limb active proprioception and validated its robustness and reliability over multiple sessions. Using this protocol, we compared the performance between young and elderly neurologically healthy adults during both active and passive proprioceptive tasks.<i>Main results.</i>Elderly participants exhibited a significant decline in accuracy when sensing limb position in both active and passive proprioceptive tasks, whereas their precision remained unchanged. These findings indicate that aging primarily affects proprioceptive accuracy rather than variability in position sense.<i>Significance.</i>Our findings contribute to the ongoing debate on age-related proprioceptive decline and highlight the importance of distinguishing between active and passive proprioception. Furthermore, our validated robotic protocol provides a reliable tool for assessing proprioception, with potential applications in studying neurological conditions in clinical settings.