This study evaluated the efficacy of tiotropium/olodaterol vs tiotropium on lung function, exercise capacity, and physical activity in patients with COPD.A total of 184 patients aged ≥40 years with COPD (Global Initiative for Chronic Obstructive Lung Disease stage II-IV) received tiotropium/olodaterol for 6 weeks, then tiotropium for 6 weeks, or vice versa. The primary endpoint was inspiratory capacity (IC) at peak post-dose.Adjusted mean IC after 6-week treatment was 1.990 L with tiotropium/olodaterol vs 1.875 L with tiotropium (difference: 115 mL; 95% CI: 77, 153; p<0.0001). Forced expiratory volume in 1 s (difference: 105 mL; 95% CI: 88, 123), forced vital capacity (difference: 163 mL; 95% CI: 130, 197), and slow vital capacity (difference: 134 mL; 95% CI: 91, 176) improved with tiotropium/olodaterol (all p<0.0001). Adjusted mean 6-min walk distance was similar between treatments in the overall population but was significantly increased with tiotropium/olodaterol in the subgroup with Global Initiative for Chronic Obstructive Lung Disease stage III/IV at baseline (difference: 18.1 m; 95% CI: 2.3, 33.9; p=0.0254). In a post hoc analysis, tiotropium/olodaterol improved the values for ≥2.0 metabolic equivalents (difference: 5.0 min; 95% CI: 0.4, 9.7; p=0.0337).Tiotropium/olodaterol significantly improved IC compared with tiotropium and potentially enhanced the exercise capacity in COPD patients. A slight improvement in physical activity of relatively more than moderate intensity was also seen with tiotropium/olodaterol.