Weak or strong muscles can have various causes, ranging in severity from 'worrying' to 'very serious'. Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. In order to diagnose weak or strong muscles, we could:
Compared to others your age, sex and size, how is your muscular strength?
Possible responses:→ Very poor
→ Average / don't know
→ Very great