The subjects in this study were overweight or obese. This is consistent with the general population in the USA, where more than one third of adults are obese. It is also consistent with other clinical studies of pulmonary rehabilitation in the USA.48–50 Subjects were excluded if they reported difficulty with walking and/or required an assistive device to walk, thereby limiting some of the potential effects of joint problems associated with obesity. The small size in each group limited our ability to explore the relationship between obesity and PA response to the intervention, but it appears that BMI did not influence response to the intervention.