Effect of high-intensity exercise on cerebral, respiratory and peripheral muscle oxygenation of HF and COPD-HF patients

•During high intensity exercise, HF patients with coexistence of COPD showed marked exercise impairments in Cox, Res and Pm when compared to patients only diagnosed with HF.•These findings demonstrate the negative impact of multimorbidity on exercise tolerance.•Thus, we highlight the novelty of our study, which may contribute to a better understanding of the metabolic, cardiorespiratory and clinical responses during high intensity constant workload exercises in this frequent multimorbidity phenotype.