Respiratory Physiology, the Brain, and How to be Better Today Than You

Breathlessness Background: Dyspnea & Affect

As athletes who push ourselves, we all know what it feels like to be out of breath. Bent over, hands on knees, gasping for air, trying not to choke on the sweat and snot dripping down our faces…

There’s so much more to being out of breath than just the overwhelming feeling that Death is trying to start a casual conversation with you. Breathlessness, also called dyspnea (pronounced: dispnia) for my fellow nerds out there, is a complex set of symptoms that can be broken down into three dimensions: work/effort of breathing, air hunger, and chest tightness. Breathlessness as a whole has both sensory and affective components. The sensory component of breathlessness refers to how you would characterize the intensity of what you’re feeling, and the affective component refers to how you would characterize your emotional response to it.

For example, a guy wearing full kit (packed rig, plate carrier with armor, etc.) might say, “I feel like my chest is tight, and on a scale of 1-10 the intensity of it is a 5, and my anxiety about it is a 2,” basically illustrating that he has almost no concern about his restricted breathing. This is common among the military, firefighters, and LEO where individuals become accustomed to restricted breathing from the amount of gear typically worn during movement. That said, you could imagine someone wearing a heavy kit for the first time claiming the intensity of chest tightness is a 9 and the anxiety about it is a 10.

So, why bother describing nuanced details of breathing? Well, because the affective (perceptual-emotional) components of breathlessness can limit athletic performance, meaning that an individual may stop exercising because he or she feels anxious about his or her breathing, not because that person can’t physically and physiologically continue or push further (Faull, et al., 2016). Not surprisingly, this is a lot worse if you have any kind of clinical limitation, like asthma. People who are clinically limited often have increased breathlessness-related anxiety, and through fear and avoidance begin to condition themselves against doing activities that may induce breathlessness.

This is bad for obvious reasons, and although I’d love to get into the details of how adopting a sedentary lifestyle is a death sentence, I’ve been trying to limit when I allow my ADD to kick in.

So, just as respiratory sensations can impact affective state, affective state can impact a person’s perception of respiratory sensations. You can think of affective state as kind of an emotional backdrop to your experience, or maybe a filter through which you experience your inner and outer environments. Examples of positive affect include happy, calm, and in control, while examples of negative affect include irritated, anxious, frightened, or out of control.

When you’re in a positive affective state, your perception of respiratory stimuli is diminished due to something called respiratory gating (Chan, et al., 2016). Respiratory gating can be described in very general and non-scientific terms as a situation where part of your brain interacts with incoming respiratory related sensory information and decides to tell some of it to fuck off, which prevents it from becoming part of your consciousness and keeps you unaware of it. This is happening constantly in our daily lives, which is why we don’t notice how our breathing feels unless we focus on it. Unfortunately, when you’re in a negative affective state, respiratory gating is diminished and you are much more aware of incoming respiratory sensations.

To bring this full circle and relate it back to athletes: your base affective state can impact your perception of your respiratory sensations, and if significant enough, may have the potential to influence your athletic performance.

How can we exploit this to work in our favor as athletes? The first thing we can do is alter our affective state prior to or during training to hopefully diminish our heightened awareness of unpleasant respiratory sensations. We can positively influence our affective state in a number of ways. Listening to music we like is one example, as self-selected music during exercise has been associated with less dyspnea reports. Another example is just generally being a good person and cultivating a positive attitude (reason #5032 for not being an asshole). Meditation and controlled breathing exercises also have a positive impact on affective state, not to mention their endless other benefits. Finally, and unsurprisingly, certain pharmacological agents are able to influence affective state by blunting our perception of distressing stimuli, but using these types of drugs can lead to potentially severe consequences depending upon the context in which they’re used.

Beyond cultivating a positive affective state, the second thing we can do for ourselves as athletes is to build up our respiratory system machinery so that the likelihood that we experience debilitating negative affect during difficult tasks is diminished. How to accomplish this is a little less obvious than cultivating a positive affective state, so let’s take a closer look.

Work of Breathing

Breathlessness is often the result of a disparity between how hard you’re working to breathe and how much air you’re actually moving into and out of your lungs.

Think about what it would feel like to breathe through a narrow straw with lots of resistance. I like to call this the milkshake analogy – and I mean milkshake like the kind you get from Sonic, not the kind that brings all the boys to the yard. Maybe a more relevant example would be to think about what it would feel like to breathe when you’re wearing an extremely heavy weight vest that prevents prevents your chest wall from expanding no matter how hard you try to inhale. The idea that’s being presented by these examples is that you’d be providing a ton of effort, described as the work of breathing, but you’d by experiencing very little air moving into your lungs.

For some, just thinking about these examples may evoke some mild anxiety or thoughts and feelings of suffocation. Completely understandable, as we’re hard-wired to defend our airways and maintain respiration at all costs.

The difference between how hard we’re working and how much ventilation we achieve is controlled and registered by our brains. The effort of our respiratory muscles is controlled by neural respiratory motor drive, or motor output. The return on our effort is simultaneously sensed throughout our respiratory system in receptors embedded within muscle tissue, airways, and joints (like in our ribs), and sent back to our brain where an output/input comparison is made and consciously sensed by us. It’s like a respiratory thermostat. When the output/input doesn’t match, especially when the output is much greater than normal due to some abnormal restrictions to breathing, it can result in breathlessness (or dyspnea, to bring the clinical term back into rotation), which in turn may negatively impact athletic performance. For example, in chest wall strapping – like wearing an extremely heavy weight vest –individuals experienced dyspnea during training and subsequently ceased exercising (Mendonca, et al., 2014).

Just as an interesting aside here, when you’re out of breath and you bend over and put your hands on your knees to breathe, there’s a reason it feels better – what you’re actually doing is decreasing the work of breathing by decreasing resistance in your airways and activating accessory respiratory muscles like your lats, which aid in expanding the volume of your thorax and improving ventilation.

Any time work/effort increases with regard to muscle activity, oxygen consumption must also increase to keep pace with the metabolism of those hard-working respiratory muscles. Thus, as the work of breathing increases, the amount of oxygen consumed by the respiratory muscles increases.

If an individual is operating at near maximal work of breathing (think running for your life with full kit and ruck), the respiratory muscles may demand nearly 15% of total oxygen consumption. This increased demand for oxygen results in increased blood flow to the respiratory muscles, and decreased blood flow and oxygen delivery to other working muscles (Harms, et al., 1997), and this increased work of breathing during strenuous exercise can limit athletic performance (Harms, et al., 2000).

The good news: when operating at submaximal effort and during non-endurance situations, these effects are either not evident or less noticeable, unless you’re working at high altitude and influenced by hypoxia, so keep that in mind if you ever want to come to my home state of Colorado and go trail running in the high alpine.

Still, that’s kind of a bummer, right? It doesn’t have to be. Our bodies are incredibly adaptable, and believe it or not, it’s actually possible to train your respiratory muscles.

Respiratory Muscle Strength Training

If you push to the exact same place of respiratory-related discomfort every time you train, you aren’t taxing your respiratory muscles or providing the stimulus they need to adapt.

It’s the same concept as training any other muscle group. The ultimate outcome of training is that your muscles get stronger, the same work or load seems easier or lighter, and you can subsequently lift heavier and heavier things. The catch with respiratory muscles is that you can’t train them using endurance-type exercises; they’re already endurance powerhouses since they have to function constantly. This leaves us with strength training as an option. The normal load on our respiratory system is pretty minimal – we’re not doing any heavy lifting with these muscles, especially not by sitting around playing Call of Duty all day, even if you get your respiratory rate up.

So, how can we lift weights with our respiratory muscles? We can’t directly, obviously, but we can add resistance to our breathing which mimics the muscle loading achieved by weight training. This is called respiratory muscle strength training (RMST). RMST can be categorized according to the two phases of breathing since different muscles are responsible for inspiration vs. expiration. Thus, we have inspiratory muscle strength training (IMST) and expiratory muscle strength training (EMST). Both have been shown to have positive outcomes on respiratory muscle function and reduce perceived dyspnea.

Although training your respiratory muscles won’t turn you into a superhuman, it has been shown to increase athletic performance (slightly) in a couple of studies and may make you feel like the strenuousness of your breathing has decreased during specific tasks (Volianitis, et al., 2001; Romer, et al., 2010).

There are a number of commercially available products out there for both IMST and EMST, but be skeptical when choosing a device if this is something you want to pursue. Look for something that allows you to change the inspiratory or expiratory resistance, as the resistance is essentially the amount of “weight” your respiratory muscles are “lifting.” You’ll want to increase resistance as your muscles adapt and get stronger. A typical training scheme would be 5 x 5 x 5, which is 5 sets of 5 (inspiration or expiration), 5 days a week. Also, be wary of products that don’t specify how they actually work, like some training masks that are designed to appeal to your ego and inner desire to look like Bane rather than your knowledge of exercise physiology.

Summary & Take Home

In any extremely taxing physical situation, it’s likely that everyone’s out of breath and in pain. Although the intensity of the breathlessness or pain might differ slightly between individuals, the affective/emotional differences can be substantial. In some people, the affective component to their breathlessness or pain may be enough to make them quit.

We’re all hard-wired to protect ourselves from imminent danger; our brains switch into fight-or-flight mode when we feel a legitimate threat (breathlessness-related anxiety level 10), and it can be extremely difficult to override the reflexes that kick in. For some people, a 10 on the anxiety scale occurs during tasks that others can do at a 5. It’s nothing to be ashamed of, as some of the differences between individuals are due to factors that are outside of our control, like genetic and environmental influences. However, other differences can be attributed to the degree of intense physical and mental training that some do and others don’t, and that’s where we all have an opportunity to be better.

Those that train their bodies and minds and truly know themselves will be much better off and more prepared to hunt ISIS – for real or just in their dreams – than those who don’t.

So, is it bad to push yourself too much? It can be, even if you’re an elite athlete. In fact, some might argue especially because you’re an elite athlete. In a study looking at the incidence of exercise induced hypoxemia (EIH) in elite endurance athletes at sea level, researchers found that EIH did not occur in any untrained or moderately train subjects when asked to perform a cycle ergometer test to (voluntary) fatigue. However, EIH did occur in over half of the highly trained endurance athletes (Powers, et al., 1988). This begs the question as to whether some highly trained athletes push themselves further and harder than the moderately trained or untrained athletes by adapting to feeling shitty and learning to not quit in those moments.

Ultimately, we all need to push ourselves, but to what degree depends on the individual. If your job depends on you being prepared for anything and being able to get yourself and others through the unexpected because your lives depend on it, then yeah, push as hard as you can and adapt to a higher level of physiological and mental stress. If your job doesn’t depend on it but you’re a warrior at heart and never settle for average, fucking push. If you’re a recreational athlete just looking to maintain a level of health and fitness, maybe you take a less aggressive approach to your training but you’re still in it to challenge yourself.

Only you know what level you’re at, and hopefully with this information you can become more self-aware and intelligently explore your own abilities, strengths, and limitations. The take home message is that in order to get better and grow at anything, you have to push yourself both physically and mentally. Stagnation is not an option. Don’t compare yourself to others either; use others’ success to motivate and inspire you, but make sure you’re paying attention to what your own body is telling you and measuring your progress against yourself.

Be better today than you were yesterday. Now go get after it.

#dieliving

Dr. Katie Pate spends her 9-5 creating medical solutions for battlefield trauma and prolonged field care, and finding ways to improve the quality of life of our Veterans. She has a PhD in Physiology and background in Neuroscience, and has conducted research in a variety of medical fields. When not nerding it up, you can find her doing extreme sports in the mountains of Colorado, unless she’s training at the range and gym, or sitting on her meditation cushion at home with her dog. He meditates, too.

Follow her:

LinkedIn: Kathryn Pate, https://www.linkedin.com/in/kathryn-pate-ba699b85/

Instagram: doc.pate, https://www.instagram.com/doc.pate/

Facebook: Katie Pate, https://www.facebook.com/katie.pate.522

References

Chan, et al., 2016, DOI: 10.3389/fphys.2016.00019

Faull, et al., 2016, DOI: 10.3389/fphys.2016.00231

Harms, et al., 1997, DOI: 10.1152/jappl.1997.82.5.1573

Harms, et al., 2000, DOI: 10.1152/jappl.2000.89.1.131

Mendonca, et al., 2014, DOI: 10.1152/japplphysiol.00950.2013

Powers, et al., 1988, PMID: 3220070

Romer, et al., 2010, DOI: 10.1080/026404102760000053