Effect of gait speed on gait rhythmicity in Parkinson's disease: variability of stride time and swing time respond differently

Silvi Frenkel-Toledo² , Nir Giladi¹^,2^,3 , Chava Peretz¹^,2 , Talia Herman¹^,2 , Leor Gruendlinger¹ and Jeffrey M Hausdorff¹^,2^,4

¹Movement Disorders Unit, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel

²Department of Physical Therapy, Sackler School of Medicine, Tel-Aviv University, Israel

³Department of Neurology, Sackler School of Medicine, Tel-Aviv University, Israel

⁴Division on Aging, Harvard Medical School, Boston, MA, USA

author email corresponding author email

Journal of NeuroEngineering and Rehabilitation 2005, 2:23doi:10.1186/1743-0003-2-23


Published:	31 July 2005

Abstract

Background

The ability to maintain a steady gait rhythm is impaired in patients with Parkinson's disease (PD). This aspect of locomotor dyscontrol, which likely reflects impaired automaticity in PD, can be quantified by measuring the stride-to-stride variability of gait timing. Previous work has shown an increase in both the variability of the stride time and swing time in PD, but the origins of these changes are not fully understood. Patients with PD also generally walk with a reduced gait speed, a potential confounder of the observed changes in variability. The purpose of the present study was to examine the relationship between walking speed and gait variability.

Methods

Stride time variability and swing time variability were measured in 36 patients with PD (Hoehn and Yahr stage 2–2.5) and 30 healthy controls who walked on a treadmill at four different speeds: 1) Comfortable walking speed (CWS), 2) 80% of CWS 3) 90% of CWS, and 4) 110% of CWS. In addition, we studied the effects of walking slowly on level ground, both with and without a walker.

Results

Consistent with previous findings, increased variability of stride time and swing time was observed in the patients with PD in CWS, compared to controls. In both groups, there was a small but significant association between treadmill gait speed and stride time variability such that higher speeds were associated with lower (better) values of stride time variability (p = 0.0002). In contrast, swing time variability did not change in response to changes in gait speed. Similar results were observed with walking on level ground.

Conclusion

The present results demonstrate that swing time variability is independent of gait speed, at least over the range studied, and therefore, that it may be used as a speed-independent marker of rhythmicity and gait steadiness. Since walking speed did not affect stride time variability and swing time variability in the same way, it appears that these two aspects of gait rhythmicity are not entirely controlled by the same mechanisms. The present findings also suggest that the increased gait variability in PD is disease-related, and not simply a consequence of bradykinesia.