Reciprocal Inhibition

What does Reciprocal Inhibition mean and why does it matter?

According to Dr. Ray Long of Bandha Yoga, “the concept of the balanced Yin/Yang appears throughout the body.” One of the ways it shows up is through a concept called reciprocal inhibition. This is a term you may be intimately or at least remotely familiar with if you have been taken a yoga teacher training. But did you know (I didn't until Julia educated me) that reciprocal inhibition happens when there is a degree of familiarity with a task? When performing a brand new task, one the body is not familiar with, the nervous system creates additionally stability (at times experienced as joint stiffness) in the body by activating agonist muscles and antagonist muscles together. This is referred to as co-activation. This helps to prevent injury and generate stability until the body is more familiar with the task. As familiarity and repetition occur over time, the co-activation of the muscles is decreased in favor of reciprocal inhibition and the movements become more efficient and more fluid. This is another example of why establishing a new pattern, even one that is good for us, is hard work. It takes a lot of energy.

When a pattern is established, then the system moves toward the more energy efficient mode of reciprocal inhibition. What exactly does this mean and why does it matter? Reciprocal inhibition is defined as the mechanism by which the motor neurons of the nervous system cause a contraction in the agonist muscles, which are the prime movers, while inhibiting the contraction in the antagonist muscles simultaneously and reciprocally. In this way the antagonist muscles remain relaxed while the agonist does the work without opposition. Isn't this a great metaphor for life - to only use as much energy as needed, to get out of our own way and trust the innate intelligence of our being? Oops, I digress. Back to reciprocal inhibition. The degree of relaxation depends upon 1) the degree of contraction of the agonist, 2) the degree of skill the body has in the operation or task, 3) the degree of familiarity with the task, 4) the degree of complication in the task, and 5) if a task is voluntary or autonomic.

In Chapter 2 of the Yoga Sutras, Patanjali says “Sthira sukham asanam,” which translates to “asana should have the dual qualities of alertness and steadiness (sthria) and relaxation and sweetness (sukham, which provides the root for the word sugar).” Reciprocal inhibition is the body’s natural intelligence of this sutra.

Again, RI is an autonomic response which at times occurs with volitional and familiar movements, but is usually automatic in movements elicited by the stretch reflex. However, we can use this natural response to assist in releasing long held tension in muscles that have difficulty releasing their contraction, possibly due to postural misalignment and imbalance. This is seen more and more frequently in the quadriceps and hamstrings. When the agonist--the quads--engage, the antagonists, the hamstrings are supposed to release. Yet because of a common postural imbalance, the tucking under of the sacrum, the quadriceps get overly stretched, which weakens them, and the hamstrings get tightly bunched. This affects the ability to adequately engage the agonist and relax antagonist. "Tight hamstrings" have become a frequent complaint in yoga classes.

Let’s play with an example that might assist with those tight hamstrings, especially understanding that the hamstrings cannot release unless the quadriceps are active. They need to have the quality of "sthria."

• Sit in Dandasana, staff pose. Support the sacrum with a wedge or folded blanket as needed to maintain neutral spine. Allow the legs to flop out, however they are showing up this day.
• Come into a forward fold (DO NOT do this if you are experiencing any back problems, as this is an example of what it feels like to not be supported). For me, as I do this, I feel a tugging at the sacrum and at the back of the knees. These are two places we do not want to feel a pulling because they are joints--this means I am not stretching a muscle, but rather possibly straining a tendon or ligament.
• Sit upright again and bend the knees slightly. Flex the feet and draw the quadriceps toward the pelvis, as if you were trying to shorten the front of the thighs. Let the back of the legs lift off the floor a little as you do this. Keeping the quads engaged like this, begin to lengthen the legs by sliding the heels away from you and pressing slightly through the ball mound of the foot. If the backs of the knees to not reach the floor, place a folded blanket under them so the hamstrings can release. You can also place a sandbag on the thighs to help them stay active while they release their weight toward the ground.
• Once again come into a forward fold. Keep the quads active and the sits bones grounded. Remember my other axiom, something has to stay grounded for something else to stretch. See if you can locate the stretch in the belly of the muscle rather than at the ends of the muscle. And of course, breathe.

Try reciprocal inhibition for yourself through this pose and others. Let me know what you experience.

By the way, I am not seeking to invoke controversy here. I know in Yin yoga we do come into postures without engaging the muscles in order to stretch the fascia and connective tissue. I would love to hear your thoughts on this and will write about this kind of passive stretching at a later date.

Shanti, Janice