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) performed over a 10m course. In their correspond-ence, the shorter course length is consid-ered as one specific protocol deviation from the ATS statement1 that does not represent a conventional 6MWT. What is the ‘con-ventional ’ 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 state-ment.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 6MWTsince 2002, of which 6 are for course lengths othe