Background: Individuals with COPD may experience ambulatory difficulty due to both effort intolerance arising from respiratory dysfunction and impaired balance control during walking. However, the trunk movement during walking has not been evaluated or adjusted for patients with COPD. The Lissajous index (LI) visually and numerically evaluates the left-right symmetry of the trunk movement during walking and is useful in clinical practice. In COPD patients, the LI is used as an indicator of the left-right symmetry of the trunk during walking. Here, we used the LI to evaluate the symmetry of COPD patients based on bilateral differences in mediolateral and vertical accelerations, and we investigated the correlation between the patients' symmetry evaluation results and their physical function.
Patients and methods: Sixteen stable COPD patients (all males; age 71.3±9.2 years) and 26 healthy control subjects (15 males; age 68.2±6.9 years) participated in this study. They performed the 10-minute walk test at a comfortable gait speed wearing a triaxial accelerometer, and we measured their trunk acceleration for the evaluation of symmetry. Motor functions were also evaluated in the patients with COPD.
Results: The average mediolateral bilateral difference and LI values of the COPD patients were significantly larger than those of the healthy subjects. The COPD patients' LI values were significantly correlated with their static balance.
Conclusion: The LI measured using a triaxial accelerometer during walking is useful in balance assessments of patients with COPD.
Keywords: Lissajou index; accelerometer; balance; chronic obstructive pulmonary disease; gait.