Fig. 5

Associations of Albuterol and outcomes in the subgroup with RV/TLC > 0.35 and ≥ 90% adherence. The effect of Albuterol on the outcome variables was examined with a repeated measure design using mixed-effect linear regression modeling with the random subject effect and fixed effect variables including age, sex, height, weight, and the corresponding baseline measure of the outcome variable. The number of participants (N), the summary statistics (mean ± standard deviation) for each outcome variables measured in the placebo visit and the albuterol visit as well as the resulted parameter estimate (PE) representing the adjusted difference and the corresponding 95% confidence interval (CI) are shown. In this subgroup analysis, N represents the number of participants in each arm of the study who met the adherence criteria of ≥ 90%. The dot-and-whisker plots represent the PE and 95% CI with colors black (scaled on the top) and red (scaled on the bottom) to distinguish outcomes in which higher versus lower values are preferable. The PE and 95% CI for the statistically significant associations were shown in bold. Abbreviations: VO₂: oxygen uptake; Watts: work stage completed in watts; V_E: minute ventilation value; RR: respiratory rate; V_T: tidal volume; VCO₂: carbon dioxide production; SpO₂: oxygen saturation; O₂-Pulse: oxygen uptake per heartbeat; EELV: end-expiratory lung volume; VFL: volume of the tidal breath that is flow limited on expiration; EFL: expiratory flow limitation; SF12: Short Form 12-Item Health Survey; IPAQ: International Physical Activity Questionnaire; MET: metabolic equivalent: MVPA: moderate to vigorous physical activities; PE: parameter estimate; CI: confidence interval