Oxygen utilization during moderate-intensity resistance and aerobic exercise in arrhythmogenic cardiomyopathy: the central role of the periphery

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AIMS: To quantify central oxygen delivery (O2D), peripheral oxygen extraction, and muscle diffusive oxygen conductance (DmO2) during upper-extremity resistance and lower-extremity aerobic exercise in patients with arrhythmogenic cardiomyopathy (ACM). METHODS AND RESULTS: Nineteen patients with ACM underwent invasive cardiopulmonary exercise testing with right heart and radial artery catheterization. Participants performed 1-min isometric handgrip (IM-HG) and bicep curl (BC) exercise at 70% maximal voluntary contraction, and 20- and 40-min supine cycling (CYC-20, CYC-40) at the first ventilatory threshold. Exercise pulmonary hypertension, defined by a cardiac output to mean pulmonary artery slope >3 mmHg/L/min, did not occur (mean 0.67 mmHg/L/min). Whole-body oxygen uptake (V̇O2) increased significantly across all modes (P < .001); however, central O2D did not increase significantly during IM-HG or BC and rose only modestly during cycling. In contrast, peripheral O2 extraction and DmO2 increased significantly across all modalities (P < .001). Dominance analysis revealed that DmO2 accounted for 77% of the variance in V̇O2 pooled across all conditions, whereas O2D accounted for only 23%. CONCLUSIONS: Moderate-intensity isometric and dynamic resistance and aerobic exercise in ACM is mediated by a predominantly peripheral, rather than central, physiological stress in our small ACM sample. This may provide preliminary results for a physiological rationale for safe exercise in this population.

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