PNF Stretching
PNF stretching (or proprioceptive muscular facilitation) is one of the most
effective forms of flexibility training for increasing range of motion (1,2).
PNF techniques can be both passive (no associated muscular contraction) or
active (voluntary muscle contraction). While there are several variations of PNF
stretching, they all have one thing in common - they facilitate muscular
inhibition. It is believed that this is why PNF is superior to other
forms of flexibility training (1,2,3,4).
Both isometric and concentric muscle actions completed immediately
before the passive stretch help to achieve autogenic inhibition
- a reflex relaxation that occurs in the same muscle where the golgi tendon
organ is stimulated. Often the isometric contraction is referred to as 'hold'
and the concentric muscle contraction is referred to as 'contract'.
A similar technique involves concentrically contracting the opposing muscle
group to that being stretched in order to achieve reciprocal inhibition
- a reflex muscular relaxation that occurs in the muscle that is opposite the
muscle where the golgi tendon organ is stimulated.
Using these techniques of 'contracting', 'holding' and passive stretching
(often referred to as 'relax') results in three PNF stretching techniques. Each
technique, although slightly different, involves starting with a passive stretch
held for about 10 seconds.
For clarity and to compare each technique, think of a hamstring stretch in
the supine (on back, face up) position for each example. The athlete places one
leg extended, flat on the floor and the other extended in the air as close to
right angles to the body as possible.
Hold-Relax
A partner moves the athlete,s extended leg to a point of mild discomfort.
This passive stretch is held for 10 seconds.
On instruction, the athlete isometrically contracts the hamstrings by
pushing their extended leg against their partner's hand. The partner should
apply just enough force so that the leg remains static. This is the 'hold' phase
and lasts for 6 seconds.
The athlete is then instructed to 'relax' and the partner completes a second
passive stretch held for 30 seconds. The athlete's extended leg should move
further than before (greater hip flexion) due to autogenic inhibition activated
in the hamstrings.
Contract-Relax
A partner moves the athlete's extended leg to a point of mild discomfort.
This passive stretch is held for 10 seconds.
On instruction, the athlete concentrically contracts the hamstrings by
pushing their extended leg against their partner's hand. The partner should
apply enough force so that there is resistance while allowing the athlete to
push their leg to the floor (i.e. through the full range of motion). This is the
'contract' phase.
The athlete is then instructed to 'relax' and the partner completes a second
passive stretch held for 30 seconds. The athlete's extended leg should move
further than before (greater hip flexion) due to autogenic inhibition activated
in the hamstrings.
Hold-Relax with Opposing Muscle Contraction
A partner moves the athlete's extended leg to a point of mild discomfort.
This passive stretch is held for 10 seconds.
On instruction, the athlete isometrically contracts the hamstrings by
pushing their extended leg against their partner's hand. The partner should
apply just enough force so that the leg remains static. This is the 'hold' phase
and lasts for 6 seconds. This initiates autogenic inhibition.
The partner completes a second passive stretch held for 30 seconds, however
the athlete is instructed to flex the hip (i.e. pull the leg in the same
direction as it is being pushed). This initiates reciprocal inhibition allowing
the final stretch to be greater.
Here are some other general guidelines when completing PNF stretching:
1. Leave 48 hours between PNF stretching routines.
2. Perform only one exercise per muscle group in a session.
3. For each muscle group complete 2-5 sets of the chosen exercise.
4. Each set should consist of one stretch held for up to 30 seconds after
the contracting phase.
5. PNF stretching is not recommended for anyone under the age of 18.
6. If PNF stretching is to be performed as a separate exercise session, a
thorough warm up consisting of 5-10 minutes of light aerobic exercise and
some dynamic stretches must precede it.
7. Avoid PNF immediately before, or on the morning of competition.
References
1) Cornelius, W.J. and M.M. Hinson. The relationship between isometric
contractions and of hip extensors and subsequent flexibility in males.
Sports Med. Phys. Fitness. 20:75-80. 1980
2)Holt, L.E., T.M. Travis, and T. Okia. Comparative study of three
stretching techniques. Percept. Mot. Skills. 31:611-16. 1970
3)Sady, S.P., M. Wortman, and D. Blanke. Flexibility Training: Ballistic,
static or proprioceptive muscular facilitation? Arch. Phys. Med Rehabil.63:261-63.
1982
4)Tanigawa, M.C. Comparison of the hold relax procedure and passive
mobilization on increasing muscle length. Phys. Ther. 52:725-35. 1972