Reciprocal Inhibition – Why You Need to Know About It

Patrick Gilbert PT, DPT, ATC, CSCS

Unless you’ve studied the human body extensively, you may have never heard the term “reciprocal inhibition”. So, what the heck is it? While the biology and science behind this phenomenon is fairly complex, enacting it in practice is actually quite simple.

Reciprocal inhibition is typically seen in agonist-antagonist muscle relationships. This relationship refers to muscles or groups of muscles that perform opposite actions from each other when they contract. For example, the quadriceps, a group of four muscles which extend or straighten the knee are considered the agonist for knee extension. In that same example of knee extension, the hamstrings, which flex or bend the knee would be the antagonist. Conversely, the hamstrings would be considered the agonist for knee flexion, while the quadriceps would be the antagonist for that action.

At the simplest level, reciprocal inhibition is the reduction in firing signal of one muscle when its antagonist is being activated. These are seen at the peripheral level with either an increase or decrease in muscle tone and overall strength of contraction. However, this phenomenon actually occurs at the spinal cord level. “Reciprocal inhibition is the spinal process of inhibition of a motor neuron pool when the antagonist motor neuron pool is activated.”¹

To make it even easier to understand, this relationship can be simplified even further. Whenever a muscle that performs one action contracts, fires or activates, the muscle(s) that perform the opposite action will be inhibited and muscle tone will decrease. Functionally, this phenomenon can provide an assist with many things, including stretching, soft tissue mobilization, joint mobilizations and even corrective exercises. For the purposes of this article, we will stick to self-stretching and self-soft tissue mobilization.

Reciprocal inhibition is the reduction in firing signal of one muscle when its antagonist is being activated

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Stretching

One of the simplest ways to utilize reciprocal inhibition is during long-duration stretching. If the goal of a stretch is to gain tissue length through a specific muscle or muscle group, would it not be very useful to utilize this principle to decrease tone in that targeted muscle? Of course! Two of the simplest forms of this are seen while stretching the hip flexors and hamstrings.

Hip Flexors
This principle is used during the Half-Kneeling 90-90 Hip Flexor Stretch. If you’ve read my previous post about this stretch, then you know that glute activation is a huge part of this stretch. While activating the glute is mainly used to assist with posteriorly tilting the pelvis in order to create a greater stretch via lumbar flexion, it also plays a role with reciprocal inhibition. The glute is one of the major extensors of the hip. If you consider that the intended muscle to be stretched in this scenario (the hip flexors) flex the hip, you will quickly see how activating the glutes will inhibit or decrease tone in the hip flexors. This will play a complementary role to the original purpose of activating the glutes and facilitate a greater stretch.

Hamstrings
Reciprocal inhibition can also play a role in stretching the hamstrings. All it takes is activation of the quadriceps. I typically recommend that you stretch one leg at a time. This helps to maintain proper spinal alignment and ensures that you get a quality stretch every time. To begin this stretch, bend the knee of the leg you are not stretching and find a nice, straight spinal posture while your other leg is out straight. You can do this seated on the floor, sitting on a bench with one leg on and the other bent to the side, or sitting on a bench with both legs off, one straight and one bent. Once you get into position, gently lean forward while maintaining a straight spine. Once you begin to feel a stretch in your hamstring, activate your quadriceps to decrease tone in your hamstrings to increase the stretch.

Soft Tissue Mobilization

Reciprocal inhibition can also be extremely useful when implementing it during soft tissue mobilization. Like stretching, this can be utilized when performing self-care, or when working with a licensed professional. We will stick with the self-soft tissue mobilization for now. The manual therapy aspect of reciprocal inhibition will be discussed in a future article. One of the easiest ways to implement this technique on yourself is while using a foam roll. Three of the simplest muscle groups to target with reciprocal inhibition for soft tissue mobility are the calves, hamstrings and lats.

Gastrocnemius/Soleus
The calves are a quick and easy muscle group to perform reciprocal inhibition on while using a foam roll. The preferred position allows for the foot and ankle to be free to move in all directions while pressure is applied to the gastroc and soleus. In this case, the antagonist for the calf musculature (plantarflexors) are the ankle dorsiflexors (tibialis anterior, extensor digitorum longus and extensor hallucis longus), which are located on the anterior side of the shin. By activating the dorsiflexors and bringing your foot toward your body, you are inhibiting the plantarflexors, creating relative relaxation in the posterior calf.

With one leg crossed over the other to allow for more pressure onto the muscles, slowly bring your foot towards you into dorsiflexion while maintaining pressure through the foam roll. You should be able to feel a noticeable difference in calf tension as you move your ankle up and down. You can hold this for several seconds, or you can perform multiple repetitions of slow and controlled dorsiflexion.

Hamstrings
Similar to the calves, performing reciprocal inhibition during soft tissue mobilization for the hamstrings is quite simple, since your knee should be allowed to move freely when using a foam roll. In the same example I used in the opening section, if the hamstrings are the agonist, the antagonist are the quadriceps. With that said, if we are looking to inhibit the hamstrings, we will need to activate the quadriceps. All we need to do to make this happen is extend the knee while placing pressure into the hamstrings via the foam roll. Just like the calf, you can perform multiple repetitions of this or hold for a handful of seconds. Rinse and repeat for any other troublesome spots.

Latissimus Dorsi
Last but not least is the latissimus dorsi. The lats primarily perform shoulder extension, adduction and internal rotation. With that said, performing shoulder flexion, abduction and external rotation will create reciprocal inhibition in your lats. Shoulder flexion can be accomplished by the anterior deltoids, abduction by the middle deltoids and external rotation by the supraspinatus, infraspinatus and teres minor rotator cuff muscles. The strongest function of the lats is shoulder extension coupled with adduction, especially from a position of slightly flexion and abduction³. With this in mind, it makes the most sense to perform active shoulder flexion with abduction in order to decrease tone in the lats. Your upper thorax should be lying at about a 45 degree angle on the foam roll, with contact below the armpit and onto the lateral rib cage. From here, slowly bring your arm forward and out to the side in one, slow and controlled motion until you feel a slight stretch with tension at the spot on the foam roller you are pressing into.

So there you have it. A few simple and actionable ways to utilize this fascinating phenomenon known as reciprocal inhibition. Try these in your fitness routines and see how much of a difference it makes in the results of your soft tissue care. Your mobility deficits will thank you!

References:

1. Hallett M. Electrophysiologic Evaluation of Movement Disorders. Aminoff’s Electrodiagnosis in Clinical Neurology (6th Edition). Elsevier. 2012. 437-453.
2. Takahashi N, Takahashi H, Takahashi O, et al. Tone-inhibiting insoles enhance the reciprocal inhibition of ankle plantarflexors of subjects with hemiparesis after stroke: an electromyographic study. PM&R. 2018 February; 10(2): 168-174.
3. Jeno SH, Varacallo M. Anatomy, Back, Latissimus Dorsi. StatPearls. Treasure Island (FL): StatPearls Publishing; 2020 January.

About the Author – Patrick Gilbert PT, DPT, ATC, CSCS

Patrick is a physical therapist, athletic trainer and personal trainer. He runs Summit Performance and Therapy in Indianapolis, Indiana. He has been training clients of all backgrounds for years and has been a practicing physical therapist since 2016. His training philosophy combines his knowledge of rehabilitation as well as strength and conditioning in order to train clients to achieve great results and avoid injuries in the process. His physical therapy practice focuses on a three-dimensional view and treatment of the body and its many parts. Treatment emphasizes manual techniques and rehabilitative exercises to get patients back to previous activity levels without pain or dysfunction.

For more information about training or rehabilitating with Patrick, contact him at SummitPerformancePT@gmail.com or visit SummitPerformancePT.com

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