The reflex that results in quick contraction of the same muscle stimulated is called the reflex.

The reflex that results in quick contraction of the same muscle stimulated is called the stretch reflex. The stretch reflex protects the muscle and it occurs in response to passive stretching of the muscle. Stretch reflex can be activated by internal forces when there is stimulation of the motor neurons from within or external forces when a load is placed on the muscle.

The reflex that results in quick contraction of the same muscle stimulated is called the myostatic or stretch reflex.
Myostatic stretch is a muscle contraction which is a response to stretching within the muscle. When a muscle spindle is stretched a signal is immediately sent to the spinal cord and a response to contract the muscle is received. Since the impulse only goes to the spinal cord and back, it is a very rapid impulse (1-2 milliseconds).