The muscle spindle stretches with the muscle fiber. If the stretch is too sudden or intense, the muscle spindle reacts by causing a contraction of the muscle to prevent injury. The Golgi tendon organ causes reflex inhibition or relaxation during a stretch that is too extreme. The technique of contracting the muscle then relaxing it before performing a static stretch produces the optimal gains in flexibility. The span of movement around a joint.
Agonist muscles are the prime movers which contract to start the movement.
Antagonist muscles are the opposing muscles in the pair which must relax for movement to occur. The body favors them, and they become stronger and the others weaker. A loss of flexibility usually occurs in the stronger group. The result of muscle imbalance is inefficient movement, injury, and postural problems. The instructor can plan exercises to correct muscle imbalances.