FIG. 18:  The Table in this Figure summarizes the results of the study by Casaburi et al.^[14]  The group that exercised at a high work rate increased their exercise duration from 6.6 min to 11.4 min, a statistically significant difference (P<0.005) and almost a doubling of exercise capacity.  The group that worked at a low rate but for longer increased their exercise capacity only a little bit, and these differences in exercise capacity were significant between the two groups (P<0.05). 

The three upper rows of the Table show data at isotime (i.e., equal energy-expenditure levels), the high work rate training group reduced their mean lactate from 6.0 to 4.0 mmol/L, compared with a significantly lower (P<0.005) drop in the low work rate group, indicating that there was a physiologic benefit from high-intensity exercise training in patients with COPD.

This was a small study with 19 patients, but it showed that COPD patients who were thought to be pump limited and unable to get a physiologic benefit from exercise could, in fact, have a dose-related physiologic benefit from exercise.  So although it was a such a small study, it had a large impact.