Practice-related improvements in posture control differ between young and older adults exposed to continuous, variable amplitude oscillations of the support surface

Abstract

Healthy older adults were repeatedly exposed to continuous, variable amplitude oscillations of the support surface to determine 1) whether age affects the capacity for postural motor learning under continuous perturbation conditions with limited predictability and 2) whether practice leads to modifications in the control strategy used to maintain balance in older adults. During training, a translating platform underwent 45-second trials of constant frequency (0.5 Hz) and seemingly random amplitude oscillations (range ± 2 to 15 cm). The middle 15 seconds of each trial contained the same sequence of oscillation amplitudes. This repeated middle segment was used for analyses because young adults in Van Ooteghem et al (2008) experienced the same segment, allowing group comparisons to be made in the present study. To examine learning, participants performed a retention test following a 24-hour delay. Kinematic data were used to derive spatial and temporal measures of whole body centre of mass (COM), trunk, thigh, and shank segment orientation, and ankle and knee angle from performance during the repeated middle segment. Results showed that with training, older adults maintained the capacity to learn adaptive postural responses in the form of improved temporal control of the COM and minimization of trunk instability at a rate comparable to young adults. With practice however, older adults maintained a more rigid, ‘platform-fixed’ control strategy which differed from young adults who shifted toward ‘gravity-fixed’ control that minimized their COM motion. This study provides important insight into the ability of older adults to demonstrate longer-term improvements in postural regulation.

Can augmented feedback facilitate learning a reactive balance task among older adults?

“…Participants in this study were healthy older adults with no known problems with balance. Other studies among healthy older adults reported improved performance and learning with practice of standing on a moving platform using similar pseudo-random waveforms to those used in the current study (Van Ooteghem et al 2009;Van Ooteghem et al 2010). However, it is possible that, for participants in the current study, the task was not sufficiently challenging for participants to show improvement throughout the acquisition period.…”

What is the most effective type of audio-biofeedback for postural motor learning?

“…This finding supports the hypothesis that ABF resulted in significant postural motor learning during the experiment, resulting in motor retention even in control trials without ABF. However, as Van Ooteghem et al [13] recently showed, improvements in postural control including change of postural strategy may occur also as a consequence of pure spontaneous learning.…”

“…It is not clear how specific biofeedback should be (amplitude and/or direction or alarm threshold) to maximize improvement in sway during stance. It is often difficult to determine how much postural stability benefits from biofeedback since it is always superimposed upon a large practice effect due to spontaneous motor learning [13]. In this study, we evaluate the effects of different types of postural sway information from ABF and the interaction between improvements from ABF and spontaneous motor learning during perturbed stance.…”

Anticipatory postural control during arm movements and floor translation

“…The postural disturbance evoked by anteroposterior floor oscillations is periodic and continuous. Subjects can acquire sensory information and anticipate the postural disturbance associated with the floor oscillation, and can therefore easily improve postural stability [26][27][28][29] . The improvement is brought by the control of individual body segments with minimum postural muscle activity 30) .…”