Postural stability during low-intensity respiratory loading in pre-COPD and healthy adults: a cross-sectional study

Pre-COPD is characterized by the presence of respiratory symptoms and/or structural abnormalities, without spirometry-confirmed airflow limitation. However, pre-COPD may be associated with extrapulmonary manifestations that are not apparent at rest. The aim of this study was to assess postural stability through center of pressure (CoP) dynamics during low-intensity inspiratory and expiratory loading between adults with pre-COPD and healthy adults.

This cross-sectional observational study included 31 volunteer adults (17 with pre-COPD, 14 healthy adults; mean age 47.9 years). CoP was calculated from ground reaction forces and torques recorded with a force plate during quiet standing across three breathing conditions (without, inspiratory, and expiratory loads). Respiratory loads were set at 10% of the individuals' maximal inspiratory and expiratory pressures. CoP mean amplitude (m^-1) and velocity (m^-1·s^-1) in anteroposterior and mediolateral directions, normalized by the base of support area, were calculated from a 30-second period, averaged across three trials.

During inspiratory loading, all mean velocity outcomes were significantly higher in adults with pre-COPD compared to healthy adults (anteroposterior: p = 0.002, 95% CI [0.991, 4.014]; mediolateral: p < 0.001, 95% CI [0.971, 3.324]; total: p = 0.002, 95% CI [1.314, 5.270]). Although mean amplitude showed no overall group difference, significant load × group interaction revealed that adults with pre-COPD exhibited a greater postural disturbance during inspiratory loading than healthy adults. Expiratory loading only significantly differentiated groups for mediolateral velocity (p = 0.034, 95% CI [0.096, 2.292]).

During quiet standing, low-intensity inspiratory loading was associated with increased CoP differences between adults with pre-COPD and healthy adults.