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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

Minimum distance between the ankles is smaller in subjects with PD than control subjects. Comparison of mean a and minimum b distance between the ankles in healthy and PD subjects across the 3 requested speeds of trial execution. Group means (±SEM) are reported. t-test p-value: *:p < 0.05
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Fig3: Minimum distance between the ankles is smaller in subjects with PD than control subjects. Comparison of mean a and minimum b distance between the ankles in healthy and PD subjects across the 3 requested speeds of trial execution. Group means (±SEM) are reported. t-test p-value: *:p < 0.05

Mentions: The minimum distance between the ankles during turns was significantly different between groups, (F = 10, p = 0.007), and across velocities (F = 3.3, p = 0.05), see Fig. 3. Specifically, the minimum distance between the two feet was significantly shorter in PD, compared to healthy subjects, at slow, preferred and fast speeds. These smaller distances between the feet in subjects with PD still hold when matching for actual speed. However, the mean distance between the ankles while turning was significantly different across velocities (F = 25, p < <0.001) with an interaction effect (F = 5, p = 0.02), but not between groups (group effect F = 3, p = 0.1), see Fig. 3.


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)

Minimum distance between the ankles is smaller in subjects with PD than control subjects. Comparison of mean a and minimum b distance between the ankles in healthy and PD subjects across the 3 requested speeds of trial execution. Group means (±SEM) are reported. t-test p-value: *:p < 0.05
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Minimum distance between the ankles is smaller in subjects with PD than control subjects. Comparison of mean a and minimum b distance between the ankles in healthy and PD subjects across the 3 requested speeds of trial execution. Group means (±SEM) are reported. t-test p-value: *:p < 0.05
Mentions: The minimum distance between the ankles during turns was significantly different between groups, (F = 10, p = 0.007), and across velocities (F = 3.3, p = 0.05), see Fig. 3. Specifically, the minimum distance between the two feet was significantly shorter in PD, compared to healthy subjects, at slow, preferred and fast speeds. These smaller distances between the feet in subjects with PD still hold when matching for actual speed. However, the mean distance between the ankles while turning was significantly different across velocities (F = 25, p < <0.001) with an interaction effect (F = 5, p = 0.02), but not between groups (group effect F = 3, p = 0.1), see Fig. 3.

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