• Exercise
• short burst
• oxygen therapy

We read with great interest the recently published article by Moore et al1 and we would like to make the following remarks.

Desaturation with exercise is still a hotly debated issue, and the papers that deal with the effectiveness of oxygen therapy during exercise in patients with chronic obstructive pulmonary disease who desaturate have not shown any benefit.2 3 It should nevertheless be pointed out that there are different types of desaturating patients with exercise. Indeed, we recently published a paper4 the results of which clearly show that only patients who desaturate before 1 min—early desaturators—during the 6-minute walking test are associated with an important desaturation during daily life activities. This is why we believe that desaturation with exercise research has to take into account whether the patients are early or late desaturators in order to reach sound clinical conclusions. Along the same lines, the effectiveness of oxygen therapy in these patients can differ according to the type of patients (early or late desaturators).