Objective: To evaluate experimentally the effects of prolonged sedentary inactivity on Parkinson’s disease (PD) motor function.

Background: A frequently described but hitherto unreported symptom among PD patients is that of temporary slowness of movement following a period of prolonged sitting. PD patients report a generalised slowness characterised by difficulty arising from sitting and walking, which improves spontaneously after 2 to 15 minutes. This phenomenon seems to occur at all stages of PD, irrespective of medication state, and can be clinically significant with regard to patient mobility and function. We propose the term Stasis Induced Akinesia (SIA) to describe this novel phenomenon.

Method: To assess the SIA phenomenon, a rater-blinded randomised controlled study was performed using validated clinical assessment tools. 19 PD patients and 6 healthy age-matched controls were included in this study. Patients were assessed ON medication and evaluated before and at 0 Mins, 5 Mins and 15 Mins after randomly being assigned to either sit or stand for an hour using the Timed Up-and-Go (TUG), the Timed 20 Metre Walk, and the MDS-Unified Parkinson’s Disease Rating Scale 3 (MDS-UPDRS3). The nonparametric Friedman’s test was used to determine the change in mobility over time.

Results: A significant worsening in mobility was observed in PD patients assigned to sitting from a mean baseline TUG time of 10.70±3.12 seconds to a time of 12.61±5.68 seconds immediately post-intervention (18% increase, p=0.019). This was corroborated by the Timed 20 Metre Walk, from a mean baseline time of 18.34±4.84 seconds to a time of 19.95±6.47 seconds at 0 Mins (9% increase, p=0.003). Similarly, there was significant worsening in motor symptoms amongst PD patients assigned to sitting, as measured using the MDS-UPDRS3, from a mean baseline score of 12.90±5.69 to a score of 18.30±8.38 after intervention (42% increase, p=0.001).

Conclusion: We observed in support of SIA a temporary worsening in motor function amongst PD patients after a period of sedentary inactivity but no worsening after an equal period of standing. SIA may be an under-recognised contributor to motor disability, particularly because it appears to occur even in the best medication state. Further validation of SIA is necessary to understand its pathophysiology and develop strategies to minimise its functional impact.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-randomised-rater-blinded-study-of-motor-consequences-of-inactivity-in-parkinsons-disease-revealing-a-new-phenomenon-stasis-induced-akinesia/