CORRESPONDENCE Authors ’ response: what

determines which 6MWT is conventional? We thank the co-chairs of the joint American Thoracic Society (ATS) and the European Respiratory Society (ERS) task force for their comments on our paper and interest in our article on reference values for the 6-min walk test (6MWT) per-formed over a 10m course. In their corres-pondence, the shorter course length is considered as one specific protocol devi-ation from the ATS statement1 that does not represent a conventional 6MWT. What is the ‘conventional ’ 6MWT? Fourteen years ago, the ATS guidelines were published with the advice to test on a 30m course. However, at that time some studies used other course lengths, as was mentioned in the statement.1 Since then, more studies2–4 and healthcare providers have used a shorter course length due to space limitations. Moreover, 14 reference equations have been established for the 6MWT since 2002, of which 6 are for course lengths other than 30 m, rangin