Distribution and Prediction Models of Maximum Expiratory Time during Lung-Conduction Exercise in Adults with Normal Pulmonary Function

Objectives: Maximum expiratory time during lung-conduction exercise (LCE), derived from Donguibogam, has been proposed as a candidate indicator of exercise performance. This study examined its distribution in adults with normal pulmonary function and developed prediction models.Methods: Maximum expiratory time was measured in 78 adults (39 men and 39 women) during LCE using a sensor-equipped mask. Its associations with age, height, and pulmonary function were examined, and prediction models were developed using age, sex, and height.Results: The median maximum expiratory time was 18.6 seconds in men and 14.2 seconds in women. Log-transformed means did not differ by sex (Welch t-test, p=0.077), and log-transformed maximum expiratory time was negatively correlated with age (r=-0.24) and positively correlated with height (r=0.24), forced vital capacity (FVC) (r=0.27), and forced expiratory volume in 1 second (FEV1) (r=0.28) (all p<0.05). The mean prediction model was significant (p=0.04) but explained limited variance (R²=0.129).Conclusions: This study presents preliminary reference data on maximum expiratory time during LCE in adults with normal pulmonary function, which may inform future studies of Korean medicine pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD).