Interoception: what it is, why it matters

My last post was on proprioception and body awareness, or kinesthesia. Proprioception, according to dictionary.com is “the unconscious perception of movement and spatial orientation arising from stimuli within the body itself.” A really interesting paper by Gaffin-Cahn, et.al points out we engage with the world through the motor system; its accuracy and its ability to self correct are dependent upon information from both the visual and the proprioceptive senses. How we accomplish any motor task depends on visual and proprioceptive feedback which can be altered by things like fatigue or practice (a pianist’s touch is a learned skill. So is a pitcher’s fastball, making both of these tasks more predictable in pianists and pitchers, respectively).

If proprioception is a sense like vision is a sense, kinesthesia is a branch of proprioception like peripheral vision is a branch of vision. Training the peripheral vision will improve aspects of vision, but it probably won’t improve the ability to focus on things really close to you. Kinesthesia, your conscious awareness of body position and how it’s moving, will improve your ability to do things like stand on one leg, but it probably won’t improve your ability to accurately jump to a rock that’s far away. It’s a branch of proprioception, but it isn’t proprioception in its entirety.

(I did find this very cool study that looked at a small group of individuals with Parkinson’s disease who underwent somatosensory feedback training. The individuals in the training group improved their ability to feel their wrist position and saw improvements that were comparable to healthy adults in similar studies. They also had greater functional range of motion which correlates to motor learning. Somatosensory training is training that uses visual and proprioception training. Your eyes and your proprioception work together to determine and create appropriate movement, so training these two systems together is a logical way to improve overall body awareness.)

Interoception is your ability to sense your internal state of your body. Researchers haven’t quite agreed on an exact definition, but Ceumen, et.al explain interoception as the product of the central nervous system. Your central nervous system consists of the nerves in the brain and the spinal cord. The somatic nervous system sends information to your central nervous system via peripheral nerve fibers, so you could say the peripheral nervous system chats with the central nervous system to help you form your perception about you and the world.

In the academic literature interoception relates to a number of things, including:

• Pain

• Negative emotions

• Anxiety

• Emotions

• Emotion regulation

• Decision making

• Subjective time perception

• Subjective self awareness

• Food and water intake

• Eating disorders

• Addiction

• Empathy

• Meditation

(This list isn’t exhaustive, but you get the idea.)

Your perception and interpretation of your internal body state is closely related to cognition and emotion, which is why when you read the list above, you see things like self awareness, anxiety, and decision making. Your ability to accurately interpret the information you are receiving about your internal state contributes to your emotional state.

Let’s say you are feeling a little bit nauseous. You assume it’s because you are about to find out bad news in the meeting you have with your boss, when in actuality, it’s from the egg you ate a few hours ago. You are taking the information regarding what you are feeling and interpreting and predicting it’s because of what’s about to happen—you interoceptive accuracy is influenced by your conscious thoughts and, in this case, is inaccurate. (Which is normal. It’s part of being human. We are constantly making predictions about our world based on past experience and our current reality.)

Your interoception can be honed just like any of your other senses (and yes, interoception is considered by some scientists to be a sense, just like vision, hearing, and touch). Interoception is unconscious, but you can become aware of certain aspects, like how you are breathing, your heart rate, and recognizing whether you are actually hungry or if that chocolate chip cookie just sounds really good. Training your overall self awareness can also create a more balanced relationship with emotions such as anxiety—for instance, if I am about to lecture to a room full of people I don’t know, I can observe my response in a more detached way. I feel my heart rate elevate, I notice my breathing quicken, and I feel that slightly jittery feeling kick in. I am also able to calmly say to myself, “you are feeling anxious because you are about to lecture to people who may or may not care about what you’re saying. And that’s okay,” which immediately takes my jitters down a notch.

Interoception is affected by things like prolonged exposure to stress or traumatic stress. People can become either hyper aware of their internal state or detach from it completely, correlating to PTSD and substance use disorder. Interestingly, people with joint hyper mobility may also have hyper-awareness surrounding interoceptive sensations. Joint hypermobility, specifically joint hyper mobility syndrome/Ehlers Danlos type 3-hypermobile syndrome, is also linked to anxiety and heightened perception of pain.

I have always felt the link between anxiety and joint hyper mobility makes sense. I imagine it goes something like this: if you don’t feel like your joints are stable and you can’t detect your body position in space, it becomes stressful to feel like you can move through the world in a safe way. If you are unsure about how you can navigate your environment, that causes fear and worry. If you don’t trust your body to support you, you become hyper-attentive to the rest of your body sensations, hence, heightened interoception. (Maybe I’m way off base, but whenever I imagine what it would be like to be hyper-mobile, this is what I come up with.)

So, to quickly recap before we get into the practical applications of interoception in a training or movement setting, interoception is not proprioception, but, because it is, for the purposes of our conversation, your interpretation of sensations that derive from the central nervous system, it is influenced by your experience of your internal state of the of the body. When you use your body, a number of things happen: muscles contract and relax, respiration rate changes and heart rate changes. Your body state changes in a way that is noticeable.

Your ability to detect how your physical body is feeling is considered your kinesthetic awareness. Your kinesthetic awareness is tied to emotional states. For instance, I have a client whose right big toe sticks straight up when she’s stressed. She works out barefoot, and it has become a running joke between us—when she takes her shoes off and her right big toe is resting on the ground, I know life is going well. When her right big toe is reaching towards the ceiling, I know she is experiencing stress.

It’s difficult to build a lot of awareness around the right big toe, but through kinesthetic drills, improving foot and toe strength, mobility, and paying attention, she notices when her big toe lifts right away. She feels her feet much more, and she has far more control than she’s ever had of her foot and ankle complex. When her big toe responds to her emotional state, I can usually get it to return back to the ground by the end of the session and she feels calmer.

More obvious examples are jaw clenching, glute clenching, and general bracing. If you can feel when you do these things it makes it easier to not do these things. If you observe how you feel emotionally when you clench/brace/tighten you can begin to establish connections between your physical and mental state.

Breath holding is another common strategy under stress. Exercise is a form of stress, so people who hold their breath when they are stressed in life often hold their breath while they’re exercising. The ability to feel your breath is an interoceptive sense, so becoming more aware of what it feels like to breathe will increase the chances you feel yourself not breathing. (So will having a teacher or coach point out to you you have stopped breathing.)

Let’s break this down a little more concretely into types of training and how they can potentially benefit interoception, beginning with cardiovascular exercise.

Cardiovascular exercise has a slew of health benefits, but the main focus today is the fact it’s correlated to reductions in anxiety. A large reason for this likely has to do with the fact cardiovascular activity decreases sympathetic nervous system activity and lower hypothalmic-hypothalamic-pituitary-adrenal axis reactivity. Basically, your physiology changes when you do regular cardiovascular activity.

In animals, exercise increases neurogenesis, or new neuron growth, which leads to neuroplasticity. So cardiovascular activity promotes learning, which improves feelings of well being through serotonin, endorphins, and BDNF; with all of those happy hormones floating around, anxiety abates and you feel calmer.

From an interoception perspective, cardiovascular activity functions as a way to improve tolerance to feelings that provoke anxiety. There is a term in the literature called anxiety sensitivity. This occurs when someone misinterprets and catastrophizes sensations associated with anxiety, such as a rapid heartbeat. Cardiovascular exercises causes rapid heart rate, helping anxiety prone individuals build up a tolerance to the very interoceptive experiences that can be interpreted as negative.

It also builds self efficacy. High self efficacy occurs when you feel like you have some way to exert control over a potential threat. In the example of cardiovascular exercise, you learn that you can cope with the stress of exercise AND it gets easier/less uncomfortable/you can go further over time. Building endurance creates feelings of strength and competency.

This brings us to training type number two: engaging with the environment or another individual as a way to improve interoception. In a study done on clinically depressed individuals by Bodin, et.al, (2004), researchers found martial arts training reduced state anxiety, improved affect, and increased self efficacy when compared to stationary bike riding.

Another study, performed by Schaffner (2017) found martial arts training caused an increased sense of body connection, as well as increased feelings of strength and empowerment in an intensive program for individuals with eating disorders. (Individuals also received yoga and art therapy, cognitive behavioral therapy and/or family-based treatment.) Poor interoceptive awareness is associated with eating disorders; the author concluded martial arts training was empowering and challenged study participants to remain aware of internal experiences and perform movements that were new and outside of their comfort zone, enhancing interoception.

You can apply the same concepts to a movement training setting if you don’t have access to things like a martial arts teacher through obstacle course creation, challenging balance, game play, and creating opportunities for people to learn skills that are outside of their comfort zone. The key is providing an environment where it’s safe to try and fail and where, with practice, people feel themselves improving. When you first try something that’s new or out of your comfort zone, your heart rate will increase and your muscles will stiffen as you try and figure out what needs to happen for you to be successful. With practice, your heart rate won’t increase as much and your muscles won’t stiffen. Your internal sense of the experience will change, creating an opportunity similar to cardiovascular training. Improvement reminds you your internal experience isn’t necessarily bad and you have the ability to change. This, ultimately, creates a feeling of control, not of your environment, but of your self.

(I use similar techniques when I am working with people who have sensitivity to specific movements. If it hurts to lift the arm one way, despite the fact there is no damage to the tissues, I have the person lift the arm a slightly different way or in a smaller range of motion so it doesn’t hurt. When a person perceives sensation as permanent, it can lead to fear, anxiety, and make the world smaller.)

This brings us to strength training, an activity that can also be empowering. A fascinating study in the journal Nature found subjects who underwent mindfulness training in conjunction with strength and cardiovascular training had actual changes in their insula, a small region of the brain that separates the frontal and parietal lobe from the temporal lobe. This area is linked to emotions and the regulation of homeostasis. Remember how interoception is the sense of your internal state and is connected to emotions? We can make the leap that mindfulness training improves interoception. (The exercise group that did not receive mindfulness training didn’t have visible changes in their insula.) Based on this study, we can’t quite make the leap strength training alone is enough to improve interoception. But we can say strength training plus mindfulness training is a combination worth exploring.

(I do a lot of this, as well. I don’t have the personality for 60 minutes of somatic work, but I frequently warm people up with mindfulness or end their sessions with mindfulness and open monitoring. I have found awareness and strength are a potent combination.)

And finally, we arrive at mindful movement. Yoga, Tai Chi, Qi Gong, Feldenkrais, Body Mind Centering… The list is long and the techniques can be a powerful way to improve interoception. Mehling, et.al (2018) found a 12-week integrative exercise program combining resistance exercise, aerobic exercise, yoga, and mindfulness-based principles led to significant improvements in interoceptive bodily awareness and positive states of mind in war veterans. Mehling, et.al (2013) found differences in interoceptive awareness between people with past or current low back pain and mind-body trained individuals. Mind-body trained individuals had at least 20 hours of teaching in things like meditation, yoga, Tai Chi, or Feldenkrais and had a different relationship to low back pain than those who did not have any mind-body training.

As I mentioned earlier, not everyone needs more interoception. Some people need less. A person’s choice of movement modalities should reflect the needs of the individual. I will re-route my sessions if someone is emphasizing the internal state too much, just like I will consistently bring a person’s attention back to his internal state if he is detached from it. Interoception is complex because we are complex; researchers are still sussing out the exact definition, but what we know is movement is good, paying attention is good, and moving outside of your comfort zone once a while makes you stronger.

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