Understanding Age-Related Changes in Proprioception through Active and Passive Tasks

Voluntary control of motor actions requires precise regulation of proprioceptive and somatosensory functions. While aging has demonstrated to decline sensory processing functions, the effect of age on proprioception remains less clear. Indeed, previous studies contradict on whether passive proprioception (i.e., during externally driven movements) is affected over age. Moreover, no studies explored age-related modifications in active proprioception (i.e., during voluntary movements). Understanding these changes is critical to identify and prevent possible causes of reduced movement performances and mobility, in particular in age-related neurological conditions such as stroke or Parkinson disease. Here, we first refined a robotic protocol to assess upper-limb active proprioception and demonstrated the robustness and reliability of outcome measures over sessions. We then compared performances between young and elderly subjects during active and passive proprioceptive tasks. We found that while the two populations of subjects performed similarly in passive proprioception, elderly subjects acuity declined during active proprioception. Importantly, we confirmed that the decline could not be explained by impairments in voluntary motor control. Our data and robotic protocols further elucidate the debate over proprioception in elderly subjects and provide evidence that robust proprioceptive assessments should be an essential measurement in clinical settings. ### Competing Interest Statement The authors have declared no competing interest.