In a recent study, Forward and Backward Walking in Parkinson Disease: A Factor Analysis, Protokinetics’ gait analysis and software assessment systems, the ZENO walkway mat and PKMAS, were used to capture footfall data and extract gait parameters for a test group of sixty-two patients between 45 and 85 years of age with idiopathic Parkinson disease (PD) and eleven healthy age-matched controls. Gait dysfunction is frequently used to assess the quality of life, risk of falling and even mortality in PD.
The purpose of this study was to explore the additive value of backwards walking in a clinical setting and to elucidate the similarities and differences in immediate (1 hour) gait response to Levodopa in forward and backward walking conditions.
Participants with Parkinson’s Disease completed walking tasks both on and off Levodopa, a prodrug of dopamine used to control bradykinetic symptoms associated with PD, such as a slowed ability to start and continue movements and impaired ability to adjust the body’s position. Bradykinesia is frequently a symptom of neurological disorders and frequently occurs in Parkinson’s Disease.
The test subjects with PD were asked to withhold levodopa medications for 12 hours prior to the study session and performed the walking tasks in the OFF-medication state. Forward walking was performed, at their normal pace, by walking around a track for a total of five passes. Backward walking, being more complex to do, was performed at their normal pace. Participants were asked to walk down a 6.10 m × 1.22 m Zeno Walkway mat with embedded pressure sensors, without making loops, for a total of four passes. Forward and backward walking impairments were separately assessed, and the tests showed that backward walking in patients with PD showed greater impairment when compared with healthy controls.
The patients with PD were then asked to take 125% of their normal levodopa medication and a 1 hour wait period was given. The walking tasks were then repeated in the ON-medication state.
The differences in backward walking and forward walking in PD patients became clear in the absence of levodopa
In response to levodopa, step velocity, step length, step width, SD and walk ratio were not significantly different from the control subjects in forward walking but remained significantly different in backward walking. This may suggest that individuals with PD have larger deficits in backward walking compared to forward walking. Another explanation could be that backward walking is a more complex walking task.
While Levodopa significantly modifies spatial aspects of forward walking in individuals with PD, such as velocity and stride length, temporal parameters of gait, like cadence and swing time, are non-responsive. The effect of levodopa on backward walking in PD is less clear.
In forward walking, the gait parameters that significantly improved between the Parkinson’s Disease subjects (OFF vs. ON) were: step velocity, step velocity CV, step length, step length CV, step width SD, step time SD, step time asymmetry, stance time, stance time SD, stance time CV, GVI and walk ratio. Of these parameters, those that were not significantly different from controls (PD ON vs. controls) were: step velocity, step velocity CV, step length, step width SD, step time SD, step time asymmetry, stance time, stance time SD, stance time CV and walk ratio.
The gait features that did not change OFF to ON and remained significantly different from controls were step length SD, step length asymmetry and swing time asymmetry. Finally, the gait parameters that were not significantly different across groups were: step velocity SD, step width, step time and swing time.
In backward walking, the gait parameters that significantly improved between the PD groups (OFF vs. ON) were step velocity, step velocity SD, step velocity CV, step length, step length SD, stance time SD, and walk ratio. Of these parameters, those that were not significantly different from controls (PD ON vs. controls) were: step velocity CV, step length SD, stance time SD, and walk ratio.
The gait features that did not change OFF to ON and remained significantly different from controls were step length CV, step time SD, step time asymmetry, stance time CV, swing time asymmetry and GVI. Finally, the gait parameters that were not significantly different across all groups were step length asymmetry, step width, step time, stance time and swing time.
Across all groups and conditions, step width, step time and swing time remained unchanged.
The study demonstrates the similarity in gait domain factors in both forward and backward walking. While domains of gait are similar in both walking tasks, levodopa response is reduced in backward walking.
Read the study here: Forward and backward walking in Parkinson disease: A factor analysis.