S6 The utility of eccentric cycling for people with COPD: acute cardiorespiratory and metabolic responses

BackgroundEccentric cycling (ECC) may be an attractive exercise modality in COPD due to lower cardiorespiratory demand and perception of effort compared to conventional concentric cycling (CON) at equivalent mechanical workloads. However, it is unknown whether ECC can be performed by individuals with COPD at an intensity able to induce metabolic adaptation.Methods13 individuals with COPD (mean ± SD age 64 ± 9 years, FEV1%pred 45 ± 19%, BMI 24 ± 4 kg.m-2, O2peak15 ± 3 ml.kg-1.min-1) and 9 age matched controls (FEV1%pred 102 ± 13%, BMI 28 ± 5 kg.m-2, O2peak23 ± 5 ml.kg-1.min-1), performed up to six 4-minute bouts of ECC and CON at matched mechanical loads of increasing intensity. In addition, 12 individuals with COPD underwent quadriceps muscle biopsies (vastus lateralis) before and immediately after 20 minutes of ECC and CON at 65% peak power. Modalities were compared using linear mixed models.ResultsThe gradient of the slope of O2 (ml.min-1)/Power (Watts) during ECC was 2.8-fold and 3.3-fold lower than CON for COPD and control participants, respectively. At matched mechanical loads, minute ventilation, heart rate, systolic blood pressure, RER (all p