When fatigue during exertion is no longer normal and requires medical investigation

Fatigue following a period of inactivity can be perfectly normal, but not every decline in exercise capacity is explained simply by a lack of fitness. When everyday activities suddenly become difficult to complete, it is important for this change to be assessed by a doctor.

The term exercise intolerance describes the difficulty of carrying out physical activities at a level considered normal for a person's age and state of health. It may manifest as disproportionate fatigue relative to the effort made, a sensation of breathlessness, palpitations, dizziness, chest pain, or an unusually slow recovery after exertion.

The causes of these symptoms can be varied: heart disease, lung conditions, anaemia, metabolic disorders, muscular problems, or side effects of infections or treatments.

A medical assessment begins with a few essential questions: when the problem first appeared, what type of exertion triggers it, whether the symptoms are worsening over time, and what other symptoms accompany them. Depending on these answers, the doctor may recommend blood tests, an electrocardiogram, a cardiac ultrasound, respiratory function tests, or a stress test.

Specialists emphasise that exercise intolerance should not be ignored, particularly when it is a new symptom, is progressively worsening, or is accompanied by warning signs.