Reciprocal Inhibition is a term used to describe how muscles “talk to one another”. Muscles work together to move joints, usually with an agonist (the driver), an antagonist (the passenger) and sometimes some synergists (backseat drivers) helping out. When the agonist (let’s say the hamstrings) contracts to bend your knee, this sends neurological messages to the antagonist (the quadriceps) to eccentrically lengthen (we often sloppily say “let go” or “switch off” but it’s more complex than that). This is how muscles communicate to one another to move joints in a coordinated way. It’s important to note that a muscle is never switched off, or deactivated - think instead of it like a coordinated tug-of-war where when one muscle starts winning, the other has to choose to let go, and vice versa. 

Reciprocal Inhibition is used in lots of ways in movement and rehabilitation. If you’ve been to the physio before you may have experienced something called Proprioceptive Neuromuscular Facilitation Stretching, or PNF stretching for short. A PNF stretch gets you to push against a force (usually the physio) or resist by using your muscles and then relax as the physio stretches you or pushes back to give you more range. This in itself is tapping into the concept of reciprocal inhibition. By asking the agonist muscle to activate, it sends neurological messages to to antagonist to “let go” or “lengthen” - almost tricking it so that when the agonist muscle switches off and as the physio applies pressure, the agonist muscle appears to have more flexibility and length than it did before.

Another example is in the Thomas Hanna Somatic work that I teach. Thomas Hanna looked at how muscles communicate and devised exercises designed to release chronic muscular tension. These exercises tap into the conversation between agonist and antagonist to help them balance out and reach a better state of equilibrium. This is done using the concept of reciprocal inhibition.

An example of this is when I teach abdominal work such as a curl up or chest lift (see picture above). I have a tendency to use the concept of reciprocal inhibition to get the desired effect of stronger curl up. My experience in my own body and one I see with a lot of clients is that their back muscles are tight, and as a result, the rectus abdominals (the 6-pack muscles) have a hard time over-riding their back muscles to curl the head and shoulders up to get a strong chest lift/curl up position. Clients will tell me their abdominals are weak. I know the feeling all too well and its completely disempowering. In fact, I was almost failed during my Pilates classes at university (during my Dance degree) because the instructor thought I was being lazy and not curling up enough in my chest lift. She wrote “weak abs” on my report and for a while I really disliked Pilates because it just felt too hard, or not quote right on my body. But I don’t have weak abdominals, they just cannot overpower how tight my back is. I see this A LOT in clients struggling with “ab work”.

Instead of focusing on the abdominals contracting and pulling the head and shoulders into the chest lift, I often use an overball for kinesthetic support and ask the client to really push the lower part of their ribs back into the ball and their head back into their hands to leverage a high curl up. Rather than pulling up off the ball, they are pushing into it, and using the feedback it provides to deepen the curl. At the same time I want their focus to be on “lengthening the muscles down each side of the spine” or “pushing back into the ball to get more length in the back of my body”. Notice I haven’t cued abdominals once.

This kind of approach places focus on the eccentric (active lengthening) phase in the back muscles but it is undeniable how intensely it fires up your abdominal wall. Cueing the exercise in this way is tapping into the concept of reciprocal inhibition to get a desired effect from an exercise without cuing the muscles needed to do said exercise. So with the client, while they are thinking about their back lengthening, their abdominals are able to fire up more strongly to keep sending messages to their back to “let go” and as a result the curl up gets stronger each time and their abs get the desired workout burn! 

Leveraging off this idea can really open up many avenues to improve your flexibility, and the Pilates equipment is perfectly designed to facilitate this. By working from the point of view of actively lengthening muscles against resistance, rather than working hard to shorten them, you’ll be able to touch your toes in no time at all! Movement restrictions often occur when the tug-of-war is too far in one direction - so ultimately, if we can balance the tug of war around each joint, our flexibility should naturally start improving in all capacities. Before you know it, you’ll be rolling out of bed in the morning with a spring in your step and cartwheeling into the car to get back to Pilates!