Patients with COPD Walk with a More Periodic Step Width Pattern as Compared to Healthy Controls

Patients with chronic obstructive pulmonary disease (COPD) are at increased risk for falls and demonstrate deficits in the mediolateral direction during standing balance. The purpose of this study is to quantify both amount and temporal structure of spatiotemporal variability while walking at various speeds. Eleven COPD patients and 11 healthy controls walked at their selfselected pace on a treadmill while spatiotemporal parameters were recorded. Both amount (standard deviation (SD)) and coefficient of variation (CV)) and temporal structure of variability were quantified from 238 steps of continuous walking at the five speeds. Step length, step time, and step width time series generated. A main effect of speed for SD and CV of step length and step time was found. No main effect for group was found indicating that patients with COPD are able to adapt the amount of variability as their healthy counterparts. Rather, the only main effect for COPD patients as compared to controls was observed in the temporal structure of variability of step width. Patients with COPD demonstrate alterations in control of the step width variability temporal pattern. Importantly, our results may be of clinical importance since alterations in step width variability are associated with diminished control in the medio-lateral plane of motion and have been implicated as a predecessor to falling and predictive of future falls. This gait abnormality may provide a mechanism for the observed higher incidence of falls in patients COPD as compared to controls