Isokinetic testing of quadriceps function in COPD: feasibility, responsiveness, and minimal important differences in patients undergoing pulmonary rehabilitation.

This was a retrospective analysis of routine records from one rehabilitation centre, and it included patients referred for pulmonary rehabilitation who were more severe and dyspnoeic, so results may not apply to milder COPD or other settings. The pulmonary rehabilitation program was multicomponent and patient-tailored, and individual exercise training parameters were not retained, so the study cannot show which component caused any quadriceps change. Responsiveness and MIDs were calculated only for patients with correct baseline and post PR tests, so patients who failed the test criteria are not represented in those estimates. MIDs were distribution-based only because correlations with 6-minute walk distance and CAT scores were below 0.3, so they may not reflect patient-important change. Total work correlated strongly with peak torque and may partly reflect strength rather than endurance, so it should not be treated as a pure endurance measure. No control group or randomisation was used, so pre-post changes cannot be attributed to pulmonary rehabilitation alone.

The BASES consortium was financially supported by Lung Foundation, the Netherlands. Jana De Brandt was funded by the Flemish government and an FWO grant. Franssen received grants and personal fees from AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline, Novartis, and TEVA outside the submitted work. van den Borst received personal lecture fees from AstraZeneca and Boehringer Ingelheim. Other authors declared no conflict of interest.

Do not read the total work increase as proof that quadriceps endurance improved. The rehabilitation program was multicomponent, and the work fatigue indexes did not change.