Exercise-based cardiac rehabilitation in individuals with heart failure with reduced ejection fraction (HFrEF) elicits clinically meaningful improvements in exercise capacity and quality of life while reducing hospital readmissions.1 Training dose is an important determinant of the response to cardiac rehabilitation, where both the volume and intensity of exercise performed are critical to the magnitude of adaptation.2 Achieving more work (intensity, or duration) within a given session likely leads to greater adaptive responses and may improve clinical outcomes following exercise-based rehabilitation.3 Ergogenic aids that facilitate an ability to perform more work during each rehabilitation session may therefore be of clinical importance. An acute bout of passive heating increases core, skin and tissue temperatures, augmenting blood flow and shear stress and subsequent oxygen delivery.4 Therefore, we aimed to assess whether acute lower-limb heating increases femoral artery blood flow and lower-limb tissue oxygenation, that translates to increased post-heating exercise performance in individuals with HFrEF.