Young and Older Adults Exhibit Proactive and Reactive Adaptations to Repeated Slip Exposure

Background. A previous study found that, with repeated exposure to slipping during a sit-to-stand task, fall incidence decreased at a similar exponential rate in young and older adults. This study investigated the adaptations responsible for this decrease. Methods. Slips were induced, using bilateral low-friction platforms, during a sit-to-stand in 60 young and 41 older healthy safety-harnessed adults. Participants underwent 5 slips, then a 6th slip (reslip) after 3–4 nonslipping trials. Between-trial adjustments in body center of mass state at seat-off were examined and correlated to the likelihoods of falling and stepping. Changes in reactive response between the first slip and reslip were investigated. Results. With repeated slipping, both young and older adults adjusted to increase their center of mass anterior position and forward velocity at seat-off (p