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Understanding Reciprocal Inhibition

I know, it sounds like a different language, but stay with me. Reciprocal inhibition is a neuromuscular reflex that affects you on a daily basis. Dysfunction with this process can lead to injury, so it is important to understand what it is and how you can use it to help you avoid pain and perform better.

Now for the science…

When a muscle is stretched, mechanoreceptors called muscle spindles, which are sensitive to change in muscle length, are stretched. This stretch increases alpha motor neuron activity which then causes the muscle to contract to maintain a regular length and avoid injury. Then, a second set of nerves are sent out to cause the opposing muscle to relax. Once the opposing muscle is inhibited, the main muscle can contract. Simply put, reciprocal inhibition is the process in which a muscle must relax on one side of a joint to allow for a muscle on theother side of the joint, typically the antagonist, to contract effectively.

This process is important because it allows for optimal joint function moving through a full range of motion. Without reciprocal inhibition, if two opposing muscles were to contract at the same time, a muscular tear would be likely to occur. One muscle MUST be inhibited in order for movement to occur safely.

Remember, it works with muscles that perform the opposite movement on a joint. Some examples of antagonistic muscles include:

  • biceps brachii and triceps brachii
  • pectoralis major and rhomboids
  • levator scapular and lower trapezius
  • gluteus maximus and iliacus
  • rectus femoris and biceps femoris
  • tibialis anterior and gastrocnemius

How you can use reciprocal inhibition to your advantage:

  • It can improve flexibility
  • Allow for greater contractions during exercise
  • Reduce the risk of injury

Flexibility deserves a separate post on it’s own, but nonetheless, it is extremely important and can be improved just by understanding the fundamentals of reciprocal inhibition. When you stretch your hamstrings, contract your quadriceps for a few seconds and then sink deeper into the hamstring stretch. What happens is an inhibitory response on the hamstrings so that the quadriceps can contract, thus allowing for the hamstrings to be pushed even further than before.

If you are anything like me, there are a few things that drive me crazy: poor workout music choices, and the inability to feel a muscle working during an exercise. If you are doing a hip bridge and feel your hamstrings or lower back working rather than your glutes; or doing rows and feel your biceps burning but nothing in your back, dysfunctional reciprocal inhibition could be to blame. A muscle that is in a shortened or tight position restricts the antagonist from firing efficiently. Remember, we want muscles to relax so the antagonist can move a joint through a full range of motion. In the case of hip bridges, the gluteus maximus is the prime mover. If the iliacus is too tight, the glute may not be able to contract fully.

A word on synergistic dominance

When the prime movers can’t fire, it leads to what is called synergistic dominance. Because the glutes aren’t firing well, the hamstrings or erectors will try to work to complete hip extension because they are synergist, or assisters, for the movement. In the case of rows, the chest may be too tight or overactive to allow for the back to fire. This will force the biceps to try to complete the row. Synergists should not be doing the work for prime movers. Performing movements with an imbalance puts you at high risk for injury and chronic pain.

Even outside of exercise, if the iliacus, or other hip flexor muscles, are shortened, the glutes will not be able to fire during everyday activity raising the risk for lumbopelvic instability and injury. If the pectoralis muscles remain shortened, the mid back muscles that pull the shoulders back may be having a hard time maintaining posture, leading to upper back and neck pain.

Reciprocal inhibition occurs without conscious thought, but if the concepts are understood, it can be used to help get out of pain and avoid injury. Now go grab a massage gun and release those tight muscles!


Written by Danielle Barker