⇛Resistance is used in treatment to:
⇛Facilitate the ability of the muscle to contract.
⇛Increase motor control and motor learning.
⇛Help the patient gain an awareness of motion and its direction.
⇛Help the patient relax (reciprocal inhibition).
Most of the PNF techniques evolved from knowing the effects of resistance.
Optimal Resistance in PNF
The amount of resistance provided during an activity must be correct for the patient’s condition and the goal of the activity. This we call optimal resistance.
The resistance for learning a functional activity like standing up from a sitting position or going down the stairs is mostly a guidance resistance to teach the patients to control these activities. Resistance for irradiation or strengthening of muscles is intensive
when a muscle contraction is resisted, that muscle’s response to cortical stimulation increases. Th e active muscle tension produced by resistance is the most eff ective proprioceptive facilitation.
Th e magnitude of that facilitation is related directly to the amount of resistance.
Proprioceptive reflexes from contracting muscles increase the response of synergistic muscles at thesame joint and associated synergists at neighboring joints.
This facilitation can spread from proximal to distal and from distal to proximal. Antagonists of the facilitated muscles are usually inhibited. If the muscle activity in the agonists becomes intense, there may be activity in the antagonistic muscle groups as well (co-contraction).
How we give resistance depends on the kind of muscle contraction being resisted.
Optimal Resistance in PNF
We define the types of muscle contraction as follows (International PNF Association, unpublished handout):
Isotonic (dynamic): The intent of the patient is to produce motion.
Concentric: Shortening of the agonist produces motion.
Eccentric: An outside force, gravity or resistance, produces the motion. The motion is restrained by the controlled lengthening of the agonist. Stabilizing isotonic: The intent of the patient is motion; the motion is prevented by an outside force (usually resistance).
Isometric (static): The intent of both the patient and the therapist is that no motion occurs.
The resistance to concentric or eccentric muscle contractions should be adjusted so that motion can occur in a smooth and coordinated manner. The antagonists of the facilitated muscles allow a coordinated activity and therefore they are sufficiently inhibited to allow that activity. Resistance to a stabilizing contraction must be controlled to maintain the stabilized position.
When resisting an isometric contraction, the resistance should be increased and decreased gradually so that no motion occurs.
It is important that the resistance does not cause pain, unwanted fatigue, or unwanted irradiation. Both the therapist and the patient should avoid breath-holding.
Timed and controlled inhalations and exhalations can increase the patient’s strength and active range of motion