This was a crossover, randomised study. The randomisation was done in 10patient blocks
with sealed opaque envelopes, and the choice of intervention was only known by the examiner at the
time of testing after the inclusion of the patient in the study (concealment of randomisation). On the
first evaluation day, the individuals performed forced spirometry and a symptomlimited incremental
exercise test on a cycloergometer. On the second day, individuals were randomised and underwent
two endurance tests while performing control breathing (CB) and PLB. CB represents the patient’s
baseline respiration, without the interference of any ventilatory strategy. The patients had a 1h
recovery period between tests, and there was a 1week interval between the first and the second
evaluation days.