Maximal walking capacity measured by ISW was increased in the PEPR group. The difference between groups in ISW performance was 51 m, which exceeds the minimum clinically important difference for this test.31 Assessor blinding was not possible for all patients; however, the ISW is externally paced and reproducible and practice walks were also performed. A randomised trial of pulmonary rehabilitation in the UK reported a similar mean increase of 71 m in stable disease. Selfreported dyspnoea on the Borg scale suggested a degree of desensitisation to exertional dyspnoea associated with this improvement. Alternatively, improvement in peripheral muscle function and hence lactate production, particularly from the quadriceps,32 33 could provide a physiological explanation for reduced ventilatory drive. Quadriceps endurance properties were not measured. No significant change in static pulmonary function was observed, but many patients struggled to perform adequate gas transfer or body plethysmography measurements following exacerbation. Dynamic inspiratory capacity measurements were not performed.34