If you’ve taken a yoga teacher training course or ever read a yoga anatomy book, you’ll most likely have come across the term reciprocal inhibition. On a simple level this concept describes how there are opposing muscle groups across a joint and by contracting one group the opposite group relaxes and we can stretch further. In a yoga class during a standing forward fold a teacher might cue something like “engage your quadriceps to relax your hamstrings.”
In reality, what actually happens is that muscles co-contract. One group often contracts more than the opposing group to allow for movement to take place, but the opposing group works to control and refine the movement. Reciprocal inhibition does takes place, just for a nano-second as our nervous system momentarily inhibits the opposing muscle group, but this is not something that we ever become aware of. Also, our muscles never fully relax, even during deep sleep. They always maintain some tone unless we are under general anaesthetic.
It’s also important to note that it isn’t possible to isolate a specific muscle group, for example, to only contract your quadriceps. The scientific world used to back Penfield’s sensory and motor homunculus model that suggested that a specific part of the brain innervated a specific muscle group. This was in part superseded by Graziano’s “behavioural repertoire” model that describes how mapping from our motor cortex to muscles is not fixed but fluid and constantly changing based on feedback!
So why are we often able to stretch further when we engage the opposite muscle groups? This isn’t so clear, but it is possibly due to the stretch becoming more active. The nervous system senses that this is a safe choice for us and allows us to move further. A deeper connection to our breath and making more intentional movements may also have a role here.
Check out my practical tutorial on reciprocal inhibition:
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