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Analyzing the Athlete Experience of Pain Through the Lens of Interoception

July 15, 2022 by

Interoception is how we understand what is going on inside our bodies. Through this process, you can recognize when you are hungry, when your heart is beating faster, and plenty of other daily experiences involving the limbic and autonomic nervous system (see more at https://morningchalkup.com/community/2022/07/12/enhancing-interoception-through-exercise/). These examples are labeled visceral afferences (meaning processing internal sensory information). There is another type of afference that extends interoception outside the body: somatic afference. This is how we perceive sensory input from our somatic system (i.e., muscles, skin). These somatic afferences help to create a more familiar signaling system, proprioception. Neuroscientist Bud Craig proposed a brand new definition in 2002 to allow interoception to include the general physiological condition of the body.

Craig's proposal, founded on functional anatomy, essentially provides the brain pathways that can represent the sensory aspects of homeostatic emotion (through humans evolving to have a direct sensory pathway to the thalamus). With the idea that interoception and homeostasis are tightly intertwined, it could be argued that interoception is the representation of sensory information about the whole body, and this information can be acted upon (i.e., the interoceptive sensation of hunger produces the behavior of eating).

Let's consider how scientists disagree on the neural pathway of nociceptors (pain receptors) to the brain to corroborate further this interoception claim connecting the body and behavior. There are multiple theories, including the pathway seen below.

  1. afferent pain signals travel throughout the body (periphery)
  2. signal enters the dorsal horn (located in the spinal cord) (Brooks & Tracey, 2015)
  3. these signals reach laminae I and synapse with relay and interneurons (Dubin & Patapoutian, 2010)
  4. relay neurons project to the brainstem and thalamus, and are relayed to other brain networks (Dubin & Patapoutian, 2010)

We can see an example of the functional neuroanatomy of pain, but it doesn't convey the emotional experience of pain, which dictates a behavioral response (I'll speak on this more later). We could also say this neuro pathway only reflects the bottom-up processing experience of pain (from the body to the brain). So, where is the brain coming into action? Where is the top-down processing in pain, and how does this influence the experience?

Interestingly, there is evidence that our perception of our pain varies with our psychological state and with the context that the pain is occurring. Furthermore, there are incidences where nociceptors can be active without pain and vice versa (Mohr & Fotopoulou, 2019). So, we don't necessarily need an afferent pain signal to experience physical pain. So, there's much more to the experience of pain than just a signal shooting up from the body to the brain.

While our first neuro pathway didn't tell the full story of pain, we can learn much more through a relatively novel concept: the pain-matrix (Mohr & Fotopoulou, 2019). This pain-matrix can be divided into the medial and lateral pain systems. These two divisions are what we will use to analyze the experience of pain through interoception.

The neuroanatomy and purpose of the lateral and medial pain systems

I would argue that how we contemplate pain is typically through the lateral pain system. It's touching the hot stove and immediately feeling searing pain in your hand. But equally (or more) important is the immediate fear you experience from this action. Once you touch the hot stove, you learn quickly not to do it again. I would argue that without the medial pain system, there wouldn't be any learning. As in my earlier paragraph, interoception and homeostasis are tightly intertwined, and interoceptive signals can cause behavior. In the above figure, the medial pain system is the emotional experience of pain, with the insula and anterior cingulate cortex as two anatomical features involved. This is important as these two structures have continually been identified as major players in interoception (Caseras et al., 2013; Ernst et al., 2014; Kuehn et al., 2016). So, we see interoceptive regions producing the emotional experience of pain. Most importantly, the phrase "affective-cognitive" (seen in the bottom right of the figure) doesn't just mean emotion.

Affective-cognitive signals are operationally defined as reflecting an interface at which emotional and cognitive processes are integrated to generate behavior. Therefore, the medial pain system isn't just relating an emotion with a physically painful experience but also producing a brand new behavior. This new behavior is the result of learning. So, how does the physical and emotional experience of pain become intertwined?

The insular cortex regulates the integration of the lateral and medial pain systems (McCabe et al., 2008; Rolls, 2010). This supports interoception as the insular cortex is the primary neuro structure of interoceptive signaling. Therefore, the central hub for interoception is crucial for associating the hot stove pain with the fear experienced and learning not to repeat this behavior. Interoception is how we change our behavior through the experience of emotion being integrated with physical pain. When we think about something like homeostasis, we may think of balance. I would define homeostasis as how the body and mind work together to keep each other safe‚ÄĒtouching a hot stove? Not safe for the body.

So, how does it relate to the experience of an athlete?

If you train, you know that a lot of emotions are involved with exercise. Think of the emotional experiences of pushing through a tough metcon. What does it feel like during? What does it feel like afterward? You might notice trends in training where during a grueling workout, you're "suffering," and directly after, you're "happy." The experience of suffering for a reason also teaches new behaviors. Your brain can integrate present pain with future emotional responses related to reward.

Interoceptively, as you're pushing your peripheral body through an uncomfortable situation, you are learning to elevate your pain threshold through the knowledge that you will gain something you want (i.e., a stronger squat, a more efficient bar-muscle-up, which you believe will make you "happy"). Here, we see a direct relationship between the integration of the lateral and medial pain systems with an interesting new variable: time. In my proposed situation, the brain can call upon previous learning experiences to increase the athlete's current tolerance to pain. In this way, the knowledge of the future emotion experienced at the end of the painful experience modulates behavior in the present. You've trained long enough for your embodied cognition to understand that suffering in the "now" can result in reward in the "later." The future emotion is integrated into the present through learning experiences. With the pending reward of positive emotion, you're able to increase your tolerance to pain and, instead of avoiding it, actually lean into it.

Another athlete experience commonly associated with pain is an injury. The emotional experience of an injury can persist far longer than the physical experience. Let's consider an athlete who has recently been rehabbed. In theory, they no longer experience pain during their training, but the fear of pain might remain. An athlete may feel fear and anxiety when performing movements that once caused or agitated the physical injury. Again, this is because, interoceptively, the athlete has been conditioned by fear through the experience of pain (and the brain wants to keep the body safe from harm, aka homeostasis). So, behaviorally, the athlete is having to fight the urge to avoid the movement that once disrupted homeostasis. The athlete may understand that the movement will no longer cause pain, but they've been conditioned to fear the movement regardless through learning experiences where that movement was integrated with the negative emotional aspect of pain. So, how can an athlete decondition the negative emotional experience of movements?

Similar to exposure therapy, you can utilize brain plasticity (the ability to change) to alter your emotional experience. In the above example of a formerly injured athlete, the insular cortex has conditioned the body to avoid a particular movement pattern to maintain homeostasis (no pain). Athletes can recondition themselves to associate more positive emotions with these movements by exposing themselves to many repetitions. Importantly, these repetitions must be pain-free (or, at the very least, at a lower level of pain). Maybe the athlete is reintroduced in a linear progression where the building blocks of the movement are utilized to reteach the movement pattern and relieve the fear and anxiety that might otherwise be experienced with the full movement. Over time, the insular cortex integrates these more positive emotions with the movement.

There's a little bit more at play here for the athlete. The athlete can increase their work capacity much quicker through the negative experience of fear or anxiety of being removed from a movement. Positive emotions are already known to improve our ability to cope with pain (Cimpean & David, 2019). The athlete can enhance their tolerance for specific exercises by eliminating negative emotions associated with them and setting a new baseline for their homeostasis. Once the movement is no longer perceived as a threat, much of the emotional valence will decrease, and the experience of pain will also diminish. Even if physical pain isn't present with a movement, emotional pain can cause difficulties for the athlete and hinder their work capacity development as seen in my final example below.

My last example of an athlete comes purely from the emotional aspect of pain. You don't have to experience physical pain to experience emotional pain (in fact, we said earlier that you don't even need an afferent pain signal to experience physical pain). If you've been doing CrossFit for a while, you've probably encountered high-skill gymnastics (i.e., muscle-ups, chest-to-bar pull-ups, handstand walking). Chances are, you've also experienced the maddening emotional frustration of trying to get better at these movements. It's one thing to miss a heavy lift and eventually give up (physically, you just don't have it), but it's a completely different beast to be physically capable of taking more reps on a movement like a muscle-up. Essentially, it's up to your brain to stop you from taking infinite reps (or at the very least to stop you from taking reps for hours).

This creates an interesting situation. I would argue that the athlete who tries a thousand reps, failed attempt after failed attempt, isn't experiencing positive emotion. I would say they're good and pissed off. I myself have some of my biggest breakthroughs when I'm running on piss and vinegar, but for fucks sake, is it an uncomfortable emotional experience. There are two main issues with this kind of learning experience:

  1. I'm conditioning my brain that I am motivated by negative emotion (via the amygdala, another important feature of our medial pain system). Now, when I'm trying to learn something new, I've taught my brain to use negative emotions during the experience. So, I can quickly turn all my learning experiences in the gym into an emotional nightmare.
  2. By conjuring up this emotional nightmare, I'm also creating a negative association between the movement and the emotional experience. I said earlier that you can experience physical pain without actually receiving an afferent signal (so, without something causing physical harm to you, you can still experience physical pain). If I keep pushing myself to take more reps and ignore my medial pain system that is so desperately trying to return me back to homeostasis, I can actually experience physical pain. The brain will find a way to get your attention. Trying to utilize negative emotion as a motivator can cause me physical pain (or something close to it).

So, by banging my head against the wall rep after rep with this shitty attitude, I've created the physical experience of pain. It's like the worst-case scenario, but it can happen. Consider an athlete who can't train because of a nagging injury, but the second they're positively motivated, all of that pain goes away. Our minds can utilize negative emotions to cause physical pain to change our behavior (to maintain homeostasis). I would argue that over time, as a more negative emotional experience is associated with the particular movement, that movement becomes much more likely to cause physical pain to the athlete. Running on piss and vinegar might get you through the training session, but it isn't going to get you through the training season, and definitely not your lifelong training experience.

As athletes, we spend a lot of our training disrupting homeostasis so that we can have physical adaptations. But a crucial emotional experience in this disruption is often ignored. Our bodies and brains don't want to have their homeostasis challenged. It takes time to learn that pain can be positive, and pain is only positive when associated with positive emotions. These emotions related to pain heavily dictate our behavior, and they can alter our ability to perform physically. So, let yourself experience the emotional side of being an athlete. If you pay attention and care for these interoceptive signals, you can likely improve your physical (and mental) outcomes. Most importantly, through training our bodies, we provide ourselves the opportunity to train our emotions and set a new standard of what homeostasis means to our bodies and our brains. You can rewire your brain, so to speak, just like you can learn a new skill. But if you want to rewire it faster (and protect yourself from pain), try to keep more positive emotions as you physically train.

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