Anticipatory and Compensatory Postural Adjustments in Response to External Lateral Shoulder Perturbations in Subjects with Parkinson’s Disease

Abstract

The purpose of this study was to investigate the anticipatory (APA) and compensatory (CPA) postural adjustments in individuals with Parkinson’s disease (PD) during lateral instability of posture. Twenty-six subjects (13 individuals with PD and 13 healthy matched controls) were exposed to predictable lateral postural perturbations. The electromyographic (EMG) activity of the lateral muscles and the displacement of the center of pressure (COP) were recorded during four time intervals that are typical for postural adjustments, i.e., immediately before (APA1, APA2) and after (CPA1 and CPA2) the postural disturbances. The magnitude of the activity of the lateral muscles in the group with PD was lower only during the CPA time intervals and not during the anticipatory adjustments (APAs). Despite this finding, subjects with PD exhibit smaller COP excursions before and after the disturbance, probably due to lack of flexibility and proprioceptive impairments. The results of this study suggest that postural instability in subjects with PD can be partially explained by decreased postural sway, before and after perturbations, and reduced muscular activity after body disturbances. Our findings can motivate new studies to investigate therapeutic interventions that optimize the use of postural adjustment strategies in subjects with PD.

Postural Responses to Sudden Horizontal Perturbations in Tai Chi Practitioners

“…Previously, Tai Chi training has been shown to improve postural control during standing [ 1 , 2 ] and walking [ 3 ], as well as the ability to recover balance after a slip [ 3 ]. The present study indicated that it could also offer an effective approach to counteract the deterioration of reactive postural control, which is seen in older adults [ 25 ] and patients with neuromuscular diseases [ 20 , 26 , 27 ]. Importantly, previous studies have already demonstrated that performing Tai Chi is safe and effective for Parkinson’s disease [ 6 ] and multiple sclerosis [ 28 ] patients.…”

“…Because adaptations to stability training are highly task-specific [ 17 ], it could be expected that reactive postural responses to external perturbations at this level are improved with Tai Chi training. Applying sudden external perturbations (by suddenly applying or releasing a load) to the upper body has been also extensively used to study postural control [ 18 , 19 , 20 , 21 , 22 ]; however, to the best of our knowledge, no study to date has examined reactive postural responses to external upper body perturbations in Tai Chi practitioners.…”

Neurophysiological analysis of the clinical pull test

“…Recently, more precisely calibrated truncal perturbations have been attempted in the laboratory with motors and pendulums (de Azevedo et al 2016; Di Giulio et al 2016). In contrast, motion tracking is a relatively simple technique (albeit still requiring specialized equipment), and this has been previously employed to assess the “push and release test” (an alternative to the more widely used pull test) (Jacobs et al 2006; Smith et al 2016).…”

“…Platform translation involves intense “bottom up” perturbations, generating an initial lower limb response as occurs when slipping on a wet floor (Horak et al 1997). In contrast, the pull test employs a “top down” perturbation, with initial displacement and response of the trunk, as may occur when bumped in a crowd, and this generates a different pattern of motor recruitment (Colebatch et al 2016; de Azevedo et al 2016; Di Giulio et al 2016; Govender et al 2015).…”

Temporal pattern in the muscles of the upper limbs and the trunk in the archery

“…APA is a pre-programmed action starting voluntarily (1,3) and reflect a feedforward control and the changes are seen in the background activity of muscles (29,62,63), it is related on previous experiences and learning of subject (64). APA are the changes in the activity of the postural muscles before postural disturbance self-generated, for example, before the rapid APA and CPA magnitude depends on direction and degree of postural disturbances classified as either internal (generated by forces and torques developed during the movement of subject) or external (produced by forces around the subject), but is not limited to this (64). It is known that the magnitude of APA depends on the direction and magnitude of disturbance and body stability.…”