When prescribing exercise for patients with cardiac disease, it is important to consider the underlying physiology of the cardiac condition. For more detailed information, see exercise for specific clinical conditions.
Ischaemic heart disease
Individuals with ischaemic heart disease, but not HF, can be prescribed longer continuous exercise tasks unless they are limited by angina symptoms. Furthermore, the use of resistance training may be less detrimental to cardiac function in these patients. The presence of co-morbid diseases such as diabetes or chronic obstructive pulmonary disease (COPD), however, may require the exercise intensity and volume to be adjusted according to symptoms and not age expectations.
In HF, the primary limitation to physical exertion is often impaired cardiac output (CO). Usually, a CO of approximately 5 litres per minute is needed to sustain organ function and prevent symptoms of exertion. Healthy people can raise their CO to 15-20 litres per minute during physical stress, however patients with HF, may be limited in their ability to increase their CO to the same extent during exertion.
In these patients, there is often insufficient blood delivery to working muscles during exercise. This is compounded by a smaller skeletal muscle mass served by a deficient capillary bed. The net result is that the ability of someone with HF to extract oxygen from the blood is impaired. This means that when considering the Fick equation in patients with HF, CO is impaired, while the arterial-venous oxygen difference is also abnormally low. It is for this reason that exercise intolerance is a hallmark feature of HF.
With respect to HF aetiology, the exercise guidelines for HFREF and HFPEF are effectively the same, with both groups benefiting to a similar degree from aerobic exercise. For older and frailer patients, as is commonly the case for those with HFPEF, resistance training may play a more significant role. In these patients, resistance training aims to improve the active muscle mass available during physical exertion without the risk of compromising systolic function.
Functional class is also relevant when prescribing exercise. Most NYHA functional class II and III HF patients are able to attend and complete centre-based exercise rehabilitation programs. However, some class III and class IV patients may initially benefit from home-based exercise approaches or adjunctive physical therapies such as functional electrical stimulation, to enable sufficient functional improvement to facilitate attendance at a group program.