Rehabilitation is an integral part of cancer care and aims to maximise the functional ability and independence of patients, whatever the stage of their disease.1 To help achieve this, there is a need to identify which (if any) symptoms limit the patient’s ability to undertake activities of daily living. Patients with cancer commonly report breathlessness on exertion, and practitioners may assume that the breathlessness is the limiting symptom and may not enquire about peripheral muscle fatigue, even though this is known to contribute to exercise limitation in patients with cardiopulmonary disease and …