Perturbation-based balance training for individuals with freezing of gait

In the current study, we conducted a randomized controlled clinical trial to assess the effect of a multisession training program based on sudden AP or ML perturbations of body balance on immediate and persistent postural response gains in individuals with PD+FoG. In addition, individuals with PD+FoG receiving muscular resistance training (RT) were employed as controls for possible gains not associated specifically with PBT, like physical activity leading to gains in muscular function and social interaction. We hypothesized that a multisession program of PBT through varied and unpredictable perturbations leads to persistent stability gains of reactive postural responses as reflected by decreased values of center of pressure (CoP) amplitude/velocity and decreased numbers of experimental near-falls. In an exploratory approach, we also tested the generalization of reactive postural responses to a context of reacting to perturbations while involved cognitively with mental operations or responding to a perturbation of higher magnitude than those experienced during training.
As the main findings, PBT led to balance stability gains in reactive responses, as indicated by decreased CoP (a) ML displacement amplitude, (b) AP/ML peak velocity, and (c) AP/ML time to peak displacement in response to perturbations. Performance gains in ML perturbations persisted over the rest interval of 30 days. PBT also led to reduced numbers of near-falls in responses to platform perturbations. Results showed no transfer either to a cognitive-motor dual-task or to faster-than-trained support base displacements.
Conclusions. A training program based on sudden balance perturbations led to persistent stability gains in reactive postural responses to different unpredictable perturbations applied when standing on a moveable platform. PBT also led to lower numbers of falls, better scores in qualitative global evaluation of body balance and reduction of fear of falling. No evidence of generalizability of performance gains to dual tasking or increased perturbation magnitude was found.

Therapeutic applicability. From a therapeutic perspective, we showed that a PBT program can lead to gains in the ability to recover body balance following an unpredictable perturbation. This increased resilience to perturbations threatening upright stance could potentially reduce the risk of falls in individuals with PD+FoG. Lack of drop-outs during the program and no cases of adverse effects are positive aspects favoring the adoption of this therapeutic strategy in clinical practice.