“If you put yourself in a position when you have to stretch outside your comfort zone, then you are forced to expand your consciousness.”
– Les Brown
Last post we explored the stretch reflex and how the lengthening of a muscle causes muscle spindles to create a response of contraction. There is a similar reflex involving the lengthening of our tendons that actually creates a response of relaxation.
The same mechanism that protects our tendons from overstretching can help us to stretch more deeply in certain postures. We can use this natural reflex to cause deeper muscular relaxation, which in turn creates deeper stretching potential. This technique is called Proprioceptive Neuromuscular Facilitation, or PNF for short. First let’s explore the reaction that takes place within our bodies during deep stretching when a large amount of stress is placed on a tendon.
The Golgi Tendon Organ
The golgi tendon organ is a proprioceptor located in the tissues where the muscle and tendons join. The GTO responds to changes in force and muscle tension. (This is different from muscle spindles which respond to changes in length.) Tendons can only stretch to about 4% of their length. As such, they need to be protected when we place a lot of force on a muscle quickly. The GTO causes muscles to relax when muscle tension reaches dangerous levels. This relaxes the tendon and prevents it from overstretching and tearing as a result.
How to use PNF
We can use this relaxation response in conjunction with isometric contraction (where muscle length stays the same but more force is added) to move further in many asanas. To do this we need to contract the same muscle that we are stretching. We create resistance within our own bodies, usually with our hands, so that this contraction takes place without any lengthening or shortening of the muscle.
This increases the muscle tension and the force on the GTO, which causes the muscle to respond by relaxing for protection. Thus, the same muscle we are ultimately aiming to stretch will relax more fully. This additional relaxation creates some slack that we can then pick up by moving deeper into the pose.
Remember the more sarcomeres that are in a relaxed state, the more an overall muscle can lengthen.
Move into your posture to establish your set length. This is as deep as you can comfortably go with correct alignment until meeting tensile resistance.
Contract (with around 20% of your strength) the stretched muscle without it moving. To do this you need to create resistance and then press into this resistance. The motion will be in the opposite direction you came into the posture.
Hold this contraction for 3 – 5 deep breaths.
Stop contracting and relax the stretched muscle.
Take up the slack by moving deeper into your posture. You should find that there is a little more space for you to move deeper.
Breathe and enjoy your new stretch!
Applying PNF to Asana
Let’s see this facilitation in action in supta padangusthasana: reclined hand to big toe pose.
Lying on your back, flex both legs. Draw one leg as high as you can, imagining you are kicking the ceiling away from you. Wrap your hands around your thigh and gently begin to pull your leg towards you, establishing the initial set length of your stretch. Now let’s apply our PNF.
Keeping your fingers interlocked behind your thigh, begin to kick your leg back down towards the floor with about 20% of your strength. The pulling of your hands should prevent your legs from moving. Maintain this isometric contraction for 3 – 5 breaths by continuing to kick your leg into your hands. Then relax your leg as much as possible and once again draw it closer to your body using the strength of your arms. You will find that there is some added depth has been created, allowing your leg to come closer to your torso.
In this example we can see how contracting the stretched muscle, the hamstrings, activates the golgi tendon organ. In supta padangustasana the hamstrings are being stretched deeply as we reach our original depth in the stretch. Pressing the leg towards the floor is a form of leg extension, which activates contraction of the hamstrings. The combination of this contracting force and lengthening of the muscle triggers the golgi tendon organs in the hamstrings to protect your tendons by relaxing your hamstrings. This increased relaxation allows you to stretch further. It is always easier to stretch a muscle the more relaxed it is.
Taking Caution With PNF
PNF is something that should be exercised with a great deal of caution. It is suggested to only contract the stretched muscle with about 20% of your strength. If you were to contract fully in a stretched state, there is a higher risk of the tendons tearing. We also want to allow ample time for our muscles to recover after applying PNF, since they are reaching new limits. To error on the side of caution it is recommended to wait 48 hours before applying PNF to the same muscles.
Common Poses to Apply PNF
Here are some other common postures in which PNF is especially effective:
Baddha Konasana (Butterfly Pose): In butterfly, place your elbows on the inside of your thighs. Engage your adductors (the muscles being stretched) by drawing your knees towards one another. Your elbows will prevent the legs from actually moving, creating isometric contraction. Hold for 3–5 breaths, relax, and take up the slack to go deeper.
Janu Sirsasana: Bend one leg to place it on the inside of the opposite side. Hinge at the hips and bend forward with a straight spine, drawing your chest towards your outstretched thigh. Engage your quadriceps to relax your hamstrings. Bend your stretched knee about 20 degrees to allow for more force to be applied (even though this will lessen the hamstring stretch initially). Press your heel forward into your mat to engage the hamstrings without any movement in the leg occurring. Keeping pressing with 20% of your strength for 3–5 breaths. Stop pressing your heel down, relax your hamstrings, and use your quadriceps to straighten your leg. Take advantage of the space you’ve created to fold forward more deeply. Make sure to repeat on the other side!
Hanumansana (Splits): If you want to get into the splits, PNF is one of the most effective ways. Check out this video for step-by-step instructions.
The best way to understand this technique is to start applying it to your personal practice. Always practice mindfully and be aware of what your body is telling you. Our bodies have a great amount of wisdom. Wisdom is gained through experience, so expand the wisdom of your body by experiencing this technique with a mindful approach. You just might find that the space you create to deepen in your postures also creates more space for deeper self-awareness.