LEWIS: PNF stretching Flashcards
PNF used alternating contraction and relaxation movements for
Flexibility
PNF=
Proprioceptive neuromuscular facilitation
PNF techniques can be both
Passive (no associated muscular contraction)
Active (voluntary muscle contraction)
PNF facilitate or help the body’s muscular
Inhibition
Most practical style of PNF is the
CRAC technique
CRAC =
Contract
Relax
Antagonist
Contract
CRAC uses isometric muscle contractions as it’s
Basis
Isometric muscle contractions completed immediately before a passive stretch help to achieve
Autogenic inhibition - muscles gradually relax
Muscle spindles sense how fast a muscle is being stretched and, when activated, produce the
Stretch reflex
Muscle spindles are highly specialised receptors located within muscle cells, which protect the muscle from
Injury (overstretching and tearing)
Stretch reflex causes the muscle to
Contract and prevents overstretching of the joint
Also located within the muscles tendon is another sensor called the
Golgi tendon organ (GTO)
GTO senses how much tension is being placed on the
Tendon
Autogenic inhibition is reflex relaxation that occurs in the same muscle where the
GTO is stimulated
GTO differs from the muscle spindle in that when activated it
Relaxes the muscle, so that the stretch being applied does not cause tearing or overactivity of the nerve fibres
Often isometric referred to as ‘hold’ and concentric referred to as
‘Contract’
PNF is
Best performed with a partner - make sure they are attentive and focused on the performer so as not to cause overstretching
General guidelines for PNF (5) =
- Avoid PNF immediately before, or in the morning of, a competition and leave 48h between PNF stretching routines
- Perform only one exercise per muscle group in a session - attempt 2-5 sets
- Each set should consist of 1 stretch held up to 30s after the contracting phase
- Not recommend for under 18s
- If PNF is to be performed as a separate exercise session, a thorough warm-up must precede it
when the isometric contraction is relaxed, the stretched fibres retain their ability to stretch beyond their limit, the whole muscle is able to stretch beyond its initial maximum and you get:
increased flexibility
GTOs are activated when a muscle is stretched or contracted isometrically. They inhibit the development of too much tension in a muscle, allowing the muscle to relax and lengthen. This lengthening during a stretch also helps prevent the tendon or muscle tearing. This process is known as:
autogenic inhibition
When an agonist muscle contracts concentrically, the antagonist muscle in turn relaxes, allowing the agonist muscle to move a limb through its full range of motion without interference from tension in the antagonist. This is called:
reciprocal inhibition
PNF stretching is mainly concerned with:
reciprocal inhibition
First part of a PNF stretch is an initial passive stretch is made to get the joint into a
held, stretched position
(2) stretched agonist is isometrically contracted for:
6-10s
(3) the muscle is relaxed and its antagonist immediately performs an isometric contraction that is again held for:
6-10s
(4) The muscles are relaxed for 20s before performing another:
PNF stretch
As the agonist muscle contracts isometrically, the GTOs are activated, autogenic inhibition occurs, and the antagonist relaxes. When the antagonist of the limb being stretched contracts, the agonist muscle relaxes through:
reciprocal inhibition
These relaxed agonist muscles can be stretched further through repeated cycles of CRAC, increasing flexibility and range of motion. This is helped by the fact that the muscle spindles are:
disengaged
