Dynamic interactions between submaximal leg effort and dyspnoea during incremental CPET: implications for exercise tolerance in COPD

<bold>Background:</bold> Adding the severity of peripheral and respiratory symptoms across submaximal exercise intensities may enhance our ability to predict exercise tolerance in COPD. <bold>Aim</bold>: To determine the best approaches to quantify the cumulative burden of activity-related symptoms vis-à-vis peak work rate (WR) and O₂ uptake (VO₂) in COPD of varied severity. <bold>Methods:</bold> An AI-based software (<italic>DyVe-X</italic>) classified the dynamic burden of CR10 Borg leg effort and dyspnoea across increasing work rates during cardiopulmonary exercise testing (CPET) in 354 patients. These metrics were compared with peak symptom burden (“mild”=both scores≤2, “severe”=both>5 and “moderate”= any other combination). <bold>Results:</bold> Neither peak WR nor peak VO₂ differed between patients according to the combined peak symptom burden (<italic>p></italic>0.05). Conversely, both variables progressively decreased with the severity of dynamic symptom burden (<italic>p</italic><0.001; <bold>Figure</bold>). Controlling for COPD stage, “severe” dynamic symptom burden -but not “severe” peak symptom burden – predicted “severe” impairment in peak WR (<50% pred; OR (95% CI)= 3.69 (2.36-5.76)) and peak VO₂ (<60 % pred; 3.56 (2.23-5.68))(<italic>p</italic><0.001), <fig><object-id>erj;64/suppl_68/PA1676/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusions:</bold> Combining the dynamic assessment of leg effort and dyspnoea severity throughout incremental CPET strongly predicts peak exercise capacity in COPD. Both symptoms should be addressed to enhance exercise tolerance in this patient population.