Age-related changes in proprioception are of limited size, outcome-dependent and task-dependent

Our ability to sense the position and movement of our limbs is essential for all activities of daily living. This ability arises from the signal sent by muscle spindles to the brain. While there is clear evidence for age-related changes in the quantity of muscle spindles and in their sensitivity, behavioral assessment of age-related changes in position sense have produced mixed findings even though it is taken as textbook knowledge that proprioception declines with age. Yet, study results are difficult to compare since there is no golden standard for assessment of proprioception. Therefore, we measured upper limb proprioception across several standard proprioceptive tasks together with key factors that could influence behavioral results such as touch, motor function, and cognition in 37 young (19-32 years old) and 35 older (53-71 years old) adults. We tested age-related differences in behavioral outcomes and their associations across tasks. Our results showed that age-related effects were variable, ranging from tasks where older participants performed better to tasks where they exhibit large age-related declines. Age-related declines in position sense are outcome-dependent, sometimes requiring large samples to detect small effects. The results were confirmed by meta-analysis based on data from hundreds of participants tested in our laboratory on the exact same tasks. Associations between outcome variables across or within proprioceptive tasks were overall negligible to weak. In conclusion, age-related changes in proprioception are limited in size, task- and outcome-dependent, and current tasks used to assess proprioception do not provide consistent evidence of age-related impairment in upper limb proprioception.