Postural control learning dynamics in Parkinson’s disease: early ‎improvement with plateau in stability, and continuous progression in ‎flexibility and mobility

Background: Balance training improves postural control in Parkinson’s disease (PD). However, a systematic approach for the development of individualized, optimal training programs is still lacking, as the learning dynamics of the postural control in PD, over a training program are poorly understood.Methods: We explored the learning dynamics of the postural control in PD, during a balance-training program, in terms of the clinical, posturographic, and model-based measures. Twenty patients with PD participated in a balance-training program, 3 days a week, for 6 weeks. Clinical tests assessed functional balance and mobility pre-training, mid-training, and post-training. Center-of-pressure (COP) was recorded at four time-points during the training (pre-, week 2, week 4, and post-training). COP was used to calculate the sway measures and to identify the parameters of a patient-specific postural control model, at each time-point (stability and flexibility degree). The posturographic and model-based measures constituted the two sets of stability- and flexibility-related measures.Results: Mobility- and flexibility-related measures showed a continuous improvement during the balance-training program. In particular, mobility improved at mid-training and continued to improve to the end of the training, whereas flexibility-related measures reached significance only at the end. The progression in the balance- and stability-related measures was characterized by early improvements over the first three to four weeks of training, and reached a plateau for the rest of the training. Conclusions: The progression in balance and postural stability is achieved earlier and susceptible to plateau out, while mobility and flexibility continues to improve during balance training.