Unusual Step Patterns May Contribute to Falls in COPD Patients

Patients with chronic obstructive pulmonary disease (COPD) have a higher risk of falls, which a new study suggests could be explained by their altered walking patterns compared with healthy controls. These patients may benefit from exercises to improve balance during pulmonary therapy, the researchers suggested.

The study, which is to be published in the Annals of the American Thoracic Society, involved 40 patients, half with COPD and half without, who were asked to walk on a treadmill for 3 minutes at 3 different speeds. Sensors recorded the length, width, and time of each step, and the variability of these measures within the study groups.

Across all 3 speed conditions, the researchers observed that the patients with COPD walked with a longer mean duration of time between steps, but this timing varied more than that of the control group. They also walked with a narrower step width, while their variability in width from step-to-step was decreased. Finally, the researchers noticed that the patients with COPD increased their step width as the walking speed increased, while the control group started with wider steps and walked more narrowly as the treadmill went faster.

Prior research on older populations, not specifically people with COPD, has demonstrated that step width variability, whether it is too little or too much, is associated with having fallen in the past year. Studies have also linked a higher variability in step time to a higher fall risk.

In discussing the potential mechanisms behind falls, the authors of this study hypothesized that these changes in gait among COPD patients, particularly the decreased variation in step width, might signal that they have a hard time compensating for instability. The narrower steps make a “cross-over” walking pattern more likely, which also increases the danger of falling.

To explain why these factors particularly affect those with COPD, the researchers cited studies that showed patients with COPD often demonstrate muscle fatigue and weakness, and their ankle movement is biomechanically different than that of healthy people. They also referenced research that showed patients with COPD have a harder time adjusting their balance in the medio-lateral plane of motion.

This last mechanism provides an opportunity to mitigate the risk of falling, as COPD patients would likely benefit from learning strategies for medio-lateral control and balance recovery. These exercises could be incorporated during pulmonary rehabilitation or as part of an at-home regimen to improve balance, suggested the study authors.

“The increased step time variability and decreased step width variability demonstrated by patients with COPD in the current study may provide a mechanism that could account for, at least part of, the increased fall risk in this population,” the researchers concluded.