Kinematics and postural muscular activity during continuous oscillating platform movement in children and adolescents

Abstract

The aims of this study were to (1) characterize anticipatory and reactive postural strategies in typically developing (TD) children and adolescents; (2) determine if TD youth shift from reactive to anticipatory mechanisms based on knowledge of platform movement; and (3) determine whether TD youth further modify postural strategies when additional information about the perturbation is provided. Sixteen typically developing youth aged 7-17 years stood with eyes open on a movable platform that progressively translated anteroposteriorly (20 cm peak-to-peak) through four speeds (0.1, 0.25, 0.5, and 0.61 Hz). Participants performed two trials each of experimenter-triggered and self-triggered perturbations. Postural muscle activity (1000 Hz) of the tibialis anterior, gastrocnemius, quadriceps and hamstrings and 3D whole body kinematics (100 Hz) were recorded. The Anchoring Index and marker-pair trajectory cross-correlations were calculated as indications of body stabilization. The number of steps taken to regain balance/avoid falling were counted. Transition states and steady states were analyzed separately. Generally, the higher frequencies resulted in more steps being taken, lower correlations coupled with greater temporal lags between marker trajectories, and postural muscle activity similar to older adults. The provision of self-triggered perturbations allowed participants to make the appropriate changes to their balance by use of anticipatory postural control mechanisms.

The Effects of a 5-Day Virtual-Reality Based Exercise Program on Kinematics and Postural Muscle Activity in Youth with Cerebral Palsy

“…The balance testing paradigm used was the same as that used previously in our lab (Mills & Sveistrup, 2018;Bugnariu & Sveistrup, 2006). Briefly, participants stood upright on an oscillating platform (anterior/posterior) with their eyes open, and barefoot with feet shoulderwidth apart.…”

Kinematics and postural muscular activity during continuous oscillating platform movement in children and adolescents with cerebral palsy

“…Anticipatory and reactive postural mechanisms have been identified as significant components necessary to maintain balance during both discrete and continuous perturbations [12,13]. These mechanisms develop gradually, but anticipatory processes are mastered much later than reactive mechanisms [14].…”

“…During locomotion, typically developing (TD) children start to depend on HSSS, which benefits visual input to balance, around the age of 7 years. We have previously characterized the AI strategies in TD youth when exposed to repeated, predictable perturbations [12]. However, it is unclear how youth with CP stabilize their head in this situation and whether the AI is related to inferior body segment coordination.…”

“…The oscillating platform paradigm is an experimental approach whereby both reactive and anticipatory postural control mechanisms are generated in order to deal with the same perturbation. Specifically, the initial perturbation elicits a reactive response mechanism and as the platform continues to oscillate, the participant can switch to an anticipatory mechanism [12,3]. Adaptations to the predictable oscillations can occur within just a few cycles of sinusoidal platform translations [18,3].…”

“…Sudden changes in the frequency of platform oscillation results in a new perturbation and the participant must use a reactive mechanism to respond to this change before switching again to the anticipatory mechanism once stabilized. Furthermore, when given control over when a change in frequency occurs, it is possible to make the appropriate changes to balance through the use of anticipatory postural control mechanisms prior to the onset of perturbation [12,3]. However, it remains unclear how postural impairments in youth with CP impact their ability to maintain balance and their ability to shift from one mechanism to the other.…”