Exercise training (ET) is widely used in patients with moderate-to-very-severe COPD to improve peripheral muscle function and thus exercise capacity and quality of life [9]. Unfortunately, the effects of ET in mild COPD are currently unclear. A recent systematic review identified three low-quality studies with different designs (retrospective, one group pre-posttest, and one randomized controlled trial) [10]. The authors found significant improvements in exercise capacity (effect size 0.87-1.82) and quality of life (effect size 0.24-0.86) after comparing pretest-posttest data and ET with usual care. Although these results are inconclusive and indicate that additional and more robust studies should be conducted [10], current recommendations to initiate ET include even mild disease if dyspnea or exercise limitation are present [11]. Since peripheral muscle mass and function improve with ET [9], the investigators hypothesize that this statement is correct and consequently ET will increase exercise capacity in dyspneic patients with mild COPD in comparison to usual care.