Fatigue is extremely common, but it is difficult to define. It is like art - everyone knows what they
mean by the term, but cannot explain it easily!
A simple definition might be ‘an inability to sustain work output’, work
output being either muscular effort or cognitive effort (i.e. thinking and
concentrating). It is a non-specific
symptom of many illnesses and can be a normal physical or mental sensation, or
a symptom which impairs day-to-day functioning.
Fatigue is typically described as extreme tiredness, exhaustion or a
complete lack of energy and limits a person’s activities, potentially impairing
their quality of life. It should not be confused with sleepiness and
drowsiness, or with muscle weakness.
Whilst fatigue can range from a degree of slight tiredness, it is
considered pathological when it intrudes on the regular activities of daily
living. In its most severe form -
chronic fatigue syndrome or ME (Myalgic Encephalopathy) – a person can be bed-bound
and completely dependent.
Interestingly, it has been observed that fatigue frequently improves
rather than worsens immediately after exercise.
