Abstract
In this study, 30 younger adults and 18 older adults completed a visual inverted pendulum (VIP) balancing task. The VIP paradigm was utilized to simulate two types of sudden changes in peripheral sensorimotor function that are known to change gradually with age and to degrade bipedal balance. We increased delays between joystick commands and VIP motion to simulate increased reflex delays and decreased the magnitude of joystick commands to simulate decreased muscle strength. These sudden peripheral changes were introduced to assess age-related capacity for cognitive compensation. Younger adults performed significantly better than older adults with respect to the number of pendulum falls, the mean pendulum velocity, the number of destabilizing joystick commands, and the number of corrective reactions. A post-hoc analysis empirically defined additional performance variables correlated to the number of falls, including the number of intermittent joystick commands, the mean pendulum angular position, and the number of anticipating joystick commands. All these performance variables demonstrated age-related differences in cognitive compensation processes. Older adults showed compensation for the simulated factors that are similar to the real longer reflex delays and weaker commands they experience on average. Lastly, the post-hoc analysis of balancing processes showed that performance variables associated with more falling were correlated with higher fear of falling among older adults. The findings imply that fear of falling interacts with common capacity for balancing that underlies both real falls and the inverted pendulum falls.