Muscle spasm, a
sudden, often violent contraction of muscle, is another sign of strain.
It is a protective reflex that, in a sense, is guarding that area
against further motion until there has been time for recovery.
The spasm may
last for an extended period of time, causing a great deal of pain, or it
can be of shorter duration, such as the muscle cramping that is the
result of overuse and fatigue. Rest and protection against further
injury may be all that is required.