In our pilot study already mentioned, which had included a similar population of people with COPD, we found the mean baseline 6MWD to be 365 m, with a standard deviation of 74 m.30 The acknowledged minimal clinical important difference (MCID) at that time was reported as 54 m.32 To achieve this difference in exercise capacity, for power of 0.8 and level of significance of 0.05, using a two-sided t-test for our primary outcome of 6MWD, we calculated that the cur¬rent study would require 31 participants in each arm to allow demonstration of superiority for the active intervention by this amount. Allowing for the 25% dropout rate seen in the pilot, we estimated a total of 78 participants needed to be recruited, with 1:1 randomization to the exercise intervention arm of the CDSMP plus a single supervised exercise session versus the CDSMP alone.