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The quality of turning in Parkinson's disease: a compensatory strategy to prevent postural instability?

Mellone S, Mancini M, King LA, Horak FB, Chiari L - J Neuroeng Rehabil (2016)

Bottom Line: Subjects with PD had slower turns and did not widen the distance between their feet for turning, compared to control subjects.Dynamic stability was smaller in the PD, compared to the healthy group, particularly for fast turning angles of 90°.The slower turning speeds and larger turning angles in people with PD might reflect a compensatory strategy to prevent dynamic postural instability given their narrow base of support.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical, Electronic and Information Engineering "Guglielmo Marconi", University of Bologna, Bologna, Italy.

ABSTRACT

Background: The ability to turn while walking is essential for daily living activities. Turning is slower and more steps are required to complete a turn in people with Parkinson's disease (PD) compared to control subjects but it is unclear whether this altered strategy is pathological or compensatory. The aim of our study is to characterize the dynamics of postural stability during continuous series of turns while walking at various speeds in subjects with PD compared to control subjects. We hypothesize that people with PD slow their turns to compensate for impaired postural stability.

Method: Motion analysis was used to compare gait kinematics between 12 subjects with PD in their ON state and 19 control subjects while walking continuously on a route composed of short, straight paths interspersed with eleven right and left turns between 30 and 180°. We asked subjects to perform the route at three different speeds: preferred, faster, and slower. Features describing gait spatio-temporal parameters and turning characteristics were extracted from marker trajectories. In addition, to quantify dynamic stability during turns we calculated the distance between the lateral edge of the base of support and the body center of mass, as well as the extrapolated body center of mass.

Results: Subjects with PD had slower turns and did not widen the distance between their feet for turning, compared to control subjects. Subjects with PD tended to cut short their turns compared to control subjects, resulting in a shorter walking path. Dynamic stability was smaller in the PD, compared to the healthy group, particularly for fast turning angles of 90°.

Conclusions: The slower turning speeds and larger turning angles in people with PD might reflect a compensatory strategy to prevent dynamic postural instability given their narrow base of support.

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Related in: MedlinePlus

Subjects with PD have their body COM and ECOM outside their base of support for longer duration during fast turns. Group means (±SEM) for the % of turning duration in which COM a or ECOM b fall outside the lateral base of support in 90 ° turns and matched speeds. p-value: *:p < 0.05; **:p < 0.01
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Fig4: Subjects with PD have their body COM and ECOM outside their base of support for longer duration during fast turns. Group means (±SEM) for the % of turning duration in which COM a or ECOM b fall outside the lateral base of support in 90 ° turns and matched speeds. p-value: *:p < 0.05; **:p < 0.01

Mentions: However, these results do not take into account the fact that subjects with PD completed the task at slower speeds compared to healthy subjects, nor the differences that might arise from turning at different angles. For these reasons, we looked at the same measures but matching for actual speed of navigating the path, and selecting specific turns within the path. Selected turns were 90, 135, and 180° because these turns were always performed with a consistent pattern within and between trials. Figure 4 shows that, at matched speed, subjects with PD significantly spend more time with the COM (or ECOM) outside the lateral MOS during turning 90° at fast matched speeds (>65 cm/s) compared to control subjects.Fig. 4


The quality of turning in Parkinson's disease: a compensatory strategy to prevent postural instability?

Mellone S, Mancini M, King LA, Horak FB, Chiari L - J Neuroeng Rehabil (2016)

Subjects with PD have their body COM and ECOM outside their base of support for longer duration during fast turns. Group means (±SEM) for the % of turning duration in which COM a or ECOM b fall outside the lateral base of support in 90 ° turns and matched speeds. p-value: *:p < 0.05; **:p < 0.01
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4837520&req=5

Fig4: Subjects with PD have their body COM and ECOM outside their base of support for longer duration during fast turns. Group means (±SEM) for the % of turning duration in which COM a or ECOM b fall outside the lateral base of support in 90 ° turns and matched speeds. p-value: *:p < 0.05; **:p < 0.01
Mentions: However, these results do not take into account the fact that subjects with PD completed the task at slower speeds compared to healthy subjects, nor the differences that might arise from turning at different angles. For these reasons, we looked at the same measures but matching for actual speed of navigating the path, and selecting specific turns within the path. Selected turns were 90, 135, and 180° because these turns were always performed with a consistent pattern within and between trials. Figure 4 shows that, at matched speed, subjects with PD significantly spend more time with the COM (or ECOM) outside the lateral MOS during turning 90° at fast matched speeds (>65 cm/s) compared to control subjects.Fig. 4

Bottom Line: Subjects with PD had slower turns and did not widen the distance between their feet for turning, compared to control subjects.Dynamic stability was smaller in the PD, compared to the healthy group, particularly for fast turning angles of 90°.The slower turning speeds and larger turning angles in people with PD might reflect a compensatory strategy to prevent dynamic postural instability given their narrow base of support.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical, Electronic and Information Engineering "Guglielmo Marconi", University of Bologna, Bologna, Italy.

ABSTRACT

Background: The ability to turn while walking is essential for daily living activities. Turning is slower and more steps are required to complete a turn in people with Parkinson's disease (PD) compared to control subjects but it is unclear whether this altered strategy is pathological or compensatory. The aim of our study is to characterize the dynamics of postural stability during continuous series of turns while walking at various speeds in subjects with PD compared to control subjects. We hypothesize that people with PD slow their turns to compensate for impaired postural stability.

Method: Motion analysis was used to compare gait kinematics between 12 subjects with PD in their ON state and 19 control subjects while walking continuously on a route composed of short, straight paths interspersed with eleven right and left turns between 30 and 180°. We asked subjects to perform the route at three different speeds: preferred, faster, and slower. Features describing gait spatio-temporal parameters and turning characteristics were extracted from marker trajectories. In addition, to quantify dynamic stability during turns we calculated the distance between the lateral edge of the base of support and the body center of mass, as well as the extrapolated body center of mass.

Results: Subjects with PD had slower turns and did not widen the distance between their feet for turning, compared to control subjects. Subjects with PD tended to cut short their turns compared to control subjects, resulting in a shorter walking path. Dynamic stability was smaller in the PD, compared to the healthy group, particularly for fast turning angles of 90°.

Conclusions: The slower turning speeds and larger turning angles in people with PD might reflect a compensatory strategy to prevent dynamic postural instability given their narrow base of support.

Show MeSH
Related in: MedlinePlus