High body mass index (BMI) and low cardiorespiratory fitness (CRF) are important modifiable risk factors for heart failure (HF). While the individual contributions of CRF and BMI toward risk for HF are well established, the interrelationship between BMI and CRF in modifying long-term HF risk is more complex and not well understood. In this review, we discuss and summarize the available evidence-base on individual and joint contributions of obesity and low CRF toward HF risk, including the potential mechanisms through which these lifestyle risk factors may lead to HF. We also discuss the role of interventions aimed at intentional loss of weight or CRF improvement as potential HF preventive strategies. Finally, the article also highlights the modifying effects of CRF on survival in relation to the obesity paradox in patients with established HF.
Keywords: Cardiorespiratory fitness; Exercise; Heart failure; Obesity; Physical activity.