Muscle weakness happens when full effort doesn’t produce a normal muscle contraction or movement. Short-term muscle weakness is common and can be caused by something as simple as a tough workout.
However, persistent muscle weakness without apparent cause could indicate an underlying health condition. Common causes of muscle weakness can be lack of exercise, ageing, muscle injury or pregnancy. It can also occur with long-term conditions such as diabetes or heart disease. There are many other possible causes, which include stroke, multiple sclerosis, depression, fibromyalgia and chronic fatigue syndrome.