Fig. 6:  The relationship of dyspnea, physical activity, and COPD can be illustrated from a small study done in 1999 by a colleague, Sue Lareau.^[2]  Lareau and colleagues followed 34 male patients with COPD for 5 years in a Veterans Administration (VA) clinic setting.  Their lung function was measured using spirometry on them looking at their lung function and their physical activity was assessed with the Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ-M), which counts what kind of activities people with COPD do.  Lareau et all documented that over this 5-year period the mean FEV₁ decreased by about 230 mL, a drop of about –46 mL per year, which is not unusual in COPD.  However, the dyspnea, which was not related to any kind of activity measurement, did not change over this interval.  What is interesting is that then looking at the activities the patients reported with the PFSDQ-M, they reported an average 5.5 fewer activities over the 5 years, including stopping mowing the lawn, ironing, going to bars, gardening, auto and home repair, and walking a distance of one mile. 

For physicians and patients, the point here is that exertional dyspnea does not exist without exertion.  If you simply ask patients if they are short of breath, they may not necessarily think their symptoms are all that severe, but because of the distressing symptom of exertional dyspnea in patients with COPD, they often ratchet down their physical activity to avoid a distressing symptom.