Breathing for runners – part 2

PART 2: How to Breathe While Running

(Many thanks to MFV, PhD and multi-bostonian for proofreading this article)

If you only have a few seconds:

Breathing can become limiting when running and cause shortness of breath. In order to delay this phenomenon, it can be interesting to set up breathing habits while running: breathe more slowly, more deeply, through the nose, but also don’t hesitate to force the exhalation and work on the synchronization of locomotion-ventilation.

If you have a few minutes, read on…

Welcome to the second part of this summary-commentary of the article by Harbour and collaborator (2022) about breathing during running. In the first part, we took the time to understand how breathing is involved in running, assisting both energy demand and locomotion. Then we discussed situations where the respiratory function is limiting: hyperinflation of the lungs, blood detour, hyperventilation. These three problems occur when the respiratory chain is not used properly and/or is weak. They can also reinforce each other and lead to breathlessness. Do not hesitate to consult this first part. In this second part, we will discuss possible solutions to remedy this. Can certain breathing practices delay shortness of breath and therefore allow you to run longer? Or do they allow one to be out of breath at higher speeds, and thus run faster?

It should be noted that not all the proposed breathing tools have been properly tested. Thus, they are sometimes reasonable speculations rather than proven protocols, especially in a running situation. Nevertheless, they are proposed in a reasonable way because they are inspired by work based on general physiology, or on other sports such as cycling or swimming.

Slowing down the breathing rate

As explained in the previous part, a high breathing rate can cause problems during exercise (see Hyperventilation, part 1). In addition, it would seem that slow breathing is less energy consuming. But more importantly, slowing down the breathing naturally forces the athlete to compensate by increasing the breathing volume. For purely mechanical reasons, this will increase the efficiency of ventilation: more of the air breathed will reach the pulmonary alveoli¹. Still on mechanical considerations, several studies have shown that, during moderate efforts, the respiratory amplitude is quite plastic. However, at high intensity, the maximum amplitude is reached and only the respiratory rate can increase to meet the energy demand. Therefore, slowing down the respiratory rate is a strategy that is probably better suited to moderate intensity.

Another advantage of slowing down the breathing rate during exercise is the effect on the nervous system. When breathing is slow, the effort is perceived as less intense and mental resources are more available. Overall, the athlete can thus experience greater control and pleasure during the effort.

Finally, the authors of the article recommend that the respiratory rate should also be used as an indicator of effort. During a race, maintaining a constant speed can be crucial. By maintaining a constant respiratory amplitude (at 60% of the useful capacity) and a constant respiratory rate (with the help of step rate or an audio recording for example), the slightest acceleration will create a slight breathlessness. This will give the athlete a signal to slow down.

Given the lack of current data on this strategy, the authors emphasize the importance of exploring it carefully and on a case-by-case basis.

Breathing deeply

Above, we have seen that, mechanically, decreasing the breathing frequency results in increasing the breathing amplitude. This increase in volume is done by engaging the muscles of respiration. These can be inspiratory or expiratory, main or accessory. Depending on the muscles used, the breathing pattern will be either abdominal or thoracic. Abdominal breathing consists of engaging mainly the diaphragm. This breathing tends to slow the heart rate, improve post-exercise oxidative stress, posture control and blood pressure. Conversely, thoracic-dominant breathing (which uses the diaphragm less and the accessory muscles more) is associated with restricted respiratory flow, greater effort to breathe, hyperventilation and less postural stability. In addition, control of the different levels of breathing could allow for better exploitation of breathing volumes, in order to refine the initial relationship between frequency and amplitude described earlier. That being said, the benefits of diaphragm engagement are fairly well known in general but very little studied with respect to physical activity. In addition, engaging the diaphragm during exercise can seem quite counterintuitive to an athlete, especially after years of automaticity. In my opinion, this tool requires a significant amount of practice in non-physical exercise context. However, if the benefits of abdominal breathing can indeed be transposed to running, one can easily imagine that it could limit the risks of breathlessness favored by thoracic breathing, in addition to bringing more control over the effort and thoracic-lumbar coordination.

Breathing through the nose

Nasal breathing, as opposed to mouth breathing, has many advantages. That’s why it’s a priority when teaching breathing. To describe its advantages would require an entire article. For example, the nasal flow conditions the air that goes into the lungs (temperature, humidity) and filters it. In addition, the authors of the article summarized here did not mention the fact that one becomes less dehydrated when breathing through the nose: when switching from nasal to oral exhalation, water loss increases by 42% (Svensson et al., 2006). In addition, nasal breathing stimulates the production of nitric oxide, a vasodilator gas that promotes gas exchange, and a bronchodilator that opens the airways². The use of the nose also allows a better postural maintenance at the level of the head, and impacts the glotopharyngeal mechanics. Transposed to exercise, this could avoid the phenomenon of laryngeal obstruction induced by exercise (see Lung hyperinflation, part 1). Nasal breathing is also associated with better cognitive functions at rest, a benefit that is a priori desirable during exercise. Historically, it has been observed that when minute volume exceeds about 40 L/minute, nasal breathing gives way to mouth breathing. Although the data is still in its infancy, it would appear that the body is much more flexible. One study showed that even at 85% of VO_2max, subjects were able to maintain nasal breathing. Another study showed that nasal breathing athletes were able to produce the same power as uncontrolled breathing but with slower breathing, reduced hypocapnia and increased nitric oxide². We have already seen that breathing more slowly can be a beneficial strategy. We have also seen that hypocapnia can be problematic (see Hyperventilation, part 1). With regard to nitric oxide, it is possible that nitric oxide is the key to adaptation to exercise in nasal breathing. Indeed, this route allows a more restricted airflow than through the mouth. But the production of nitric oxide would “open” the airways and allow nasal breathing to fully meet energy needs. This phenomenon takes place, at least partially, and can be observed from the first session. But the complete adaptation to nasal breathing effort seems to take 10 to 12 weeks, or even 6 months. The main question mark over this tool concerns the fact that this form of breathing will favour the engagement of the diaphragm. As seen above, this is a priori desirable. But it is possible that the extra workload on the diaphragm will cause diaphragm fatigue (see Blood stealing, part 1). Therefore, it is recommended that this tool be explored cautiously and gradually, in order to strengthen this muscle as well as the others.

This tool is particularly – technically – easy to implement by the runner, through a conscious effort, by spending more and more time in nasal breathing when running. It is quite likely that the benefits of nasal breathing by conditioning and filtering the air, but also on head posture and cognitive functions are transposable during exercise: better airway health, better posture and cognition, less risks of laryngeal obstruction and hyperventilation, better diaphragm engagement. The only limiting point concerns the “opening” of the airways to allow sufficient airflow. But this point can a priori be resolved in a few months of training.

Forcing the exhale

At rest, breathing is generally quite balanced between the time spent inhaling and the time spent exhaling. It can even be slightly unbalanced in favor of the exhalation, which is in my opinion desirable (for this, I refer you again to this article). During effort, on the other hand, it is frequent that the balance moves towards inspiration to the detriment of expiration. In some cases, this can lead to limitations (see Hyperinflation of the lungs and Hyperventilation, part 1). Maintaining the balance in favor of exhalation is a tool well known to practitioners of conscious breathing. These breathing patterns act on the autonomic nervous system and allow a state of relaxation. It would seem that these effects can be transposed to the context of effort. A study on cyclists showed that a breathing pattern that favored exhalation improved cardiac variability, ventilation efficiency and O₂ consumption. Moreover, forcing exhalation consists in accentuating the use of the expiratory muscles, and in particular the deep layers of the abdominal muscles. In terms of biomechanics, such an expiration allows the diaphragm to passively increase its range of motion. It allows for a better distribution of work with the diaphragm, which therefore fatigues less quickly (see Blood stealing, part 1). In addition, the action of these expiratory muscles will have a positive impact on the stabilization of the posture. Finally, the authors hypothesize that this sharing of the breath, which emphasizes exhalation, could avoid the observation of too much intra-thoracic pressure, which would limit the performance of the heart.

During exercise, in general, the athlete will naturally engage these expiratory muscles in a more pronounced way than at rest. The use of this tool therefore consists of forcing this mechanism, for example by trying to expel more air from the lungs than one would instinctively do. This is why this tool, even if quite simple, may appear a little unnatural and may require a little more time to be assimilated. The authors of the article even suggest implementing this tool by combining it with a nasal vibration, comparable to the bee breath in yoga (Bhramari Pranayama). This can help slow down exhalation while increasing the production of nitric oxide in the nasal cavities, and in particular promote the opening of the airways (see Breathing through the nose, above). Note that this tool seems to give good results in the context of mountaineering (lower heart rate, less fatigue…), although more studies are needed to confirm these observations.

Synchronizing ventilation and locomotion

The number of steps per respiratory cycle has been well studied, particularly in the context of running. This ratio is quite variable: values of 3, 4, 5, 6 and 8 have been reported. As we have seen previously, this synchronization brings benefits and seems to be implemented spontaneously (see Breathing as an aid to locomotion, part 1). Implementing this tool, by forcing a different synchronization than the one that would be observed spontaneously, can be a strategy for implementing the first tool described, namely slowing down the breathing (see above). Indeed, it can be complicated to count the number of breaths per minute, especially when running. On the other hand, an athlete who sets up a cadence, for example 180 steps per minute, will be able to match a given breathing rate to that cadence. It has even been proposed that variations in respiratory rate, over a constant cadence, can be used like the gears of a car. One application of this synchronization between ventilation and locomotion is to favor an odd ratio, such as 5 or 7 steps per breath. The idea behind this is to prevent side stitch. The causes of this phenomenon are not completely clear but it is known that it affects about 70% of runners. It is thought that the phrenic nerve, which stimulates the contraction of the diaphragm, could be irritated by the repetition of the end of the exhalation coinciding with the impact of the right foot on the ground. An odd ratio of 5 or 7 steps per breath would allow the exhalation to end on an alternating left and right foot impact. Finally, it is likely that synchronizing breathing and locomotion would have a psychological benefit. It would help the athlete to enter into a throbbing and immersive flow, leading to a state of relaxation. This would then result in a decrease in energy expenditure and thus save this precious energy, especially during long distances.

Conclusion

Many of these tools correspond to the basis of natural/complete/functional breathing found in the schools of conscious breathing (REBO₂T, Oxygen Advantage) which form the essence of my teaching. Some of these tools are therefore crucial to implement outside the context of physical effort: nasal breathing, abdominal breathing, and breathing slowly. Moreover, in my opinion, the authors do not insist enough on the interest of working on breathing at rest (which will a priori have benefits on the quality of life) before transposing these principles into the context of running. With the REBO₂T method, the integration of the respiratory chain with postural work and movement makes this strategy even more interesting. Furthermore, it is interesting to see that the tools described in the Harbour et al. article are in fact all interconnected: breathing through the nose (tool 3) will promote engagement of the diaphragm (tool 2) and this will a priori slow down breathing (tool 1). Similarly, focusing on the breathing rhythm will easily integrate the breathing frequency (tool 1) and the ventilation-locomotion synchronization (tool 5). Forcing the exhalation (tool 4) will allow to slow down the breathing (tool 1) by insisting on the exhalation while printing a specific breathing rhythm, which will allow to work on the synchronization (tool 5). In addition, forcing the exhalation tool (tool 4) can also allow to work on the diaphragm rebound in order to engage the diaphragm in a more ample way (tool 2). Thus, it is likely that the implementation of one tool makes it easier to implement the others, which is good news. Note that these tools are relatively simple to implement. Breathing through the nose does not require any particular technical knowledge. Just practice. Likewise, counting your steps on the inhalation and exhalation is within the reach of everyone. As far as the actual breathing mechanics are concerned, and in particular the engagement of the diaphragm, this may require a little more work, or even a lot depending on the person. It will be difficult for a person to engage the diaphragm if they are tense in certain areas. And then it will be difficult to slow down the breath. The approach that I propose, anchored in the REBO₂T method, takes largely into account these mechanical tensions.

Finally, these tools concern the modifications that can be made during the run. These are points to work on during training with the idea of integrating them when running. But preparation exercises, on strengthening the respiratory chain or tolerance to CO₂, can help to progress. They would deserve an article, or even more, on their own and, in my opinion, they deserve to be addressed, especially when the respiratory form is correct. Moreover, the idea of this article was to convince running enthusiasts that, beyond general strengthening, “heel vs. flat vs. front” impact, technology (especially shoes), improvement can also come from modifying one’s breathing during the run.

As a bonus, let me leave a last tip: don’t forget to smile. In fact, one study showed that it was enough to save on O₂ consumption (2.23% compared to a normal attitude, or 2.78% compared to an upset face) and to decrease perceived exertion (Brick et al., 2018)³. Smiling goes very well with nasal breathing, so let’s use this combo!

🔥❄️🧠✌️

Sébastien.

¹ Minute volume is equal to the product of respiratory rate and respiratory amplitude. Therefore, in order to maintain a stable minute volume, a decrease in frequency implies an increase in amplitude. However, when we breathe a certain volume of air, not all of this air reaches the alveoli. A certain volume is unusable. This is the dead volume. Breathing more will “dilute” the impact of this dead volume of the respiratory system. A blog post will be dedicated to this soon.

² Nitric oxide also has an antibacterial and antiviral action, which can obviously be very useful in the respiratory tract. It is also involved in memory or erection. But that’s another story.

³ In a sample of 24 people, running about 40 km per week in 3-4 sessions, including 13 male and 11 female runners. It would seem, however, that this smile trick works better in runners than in women runners…

References:

Brick, N. E., McElhinney, M. J., Metcalfe, R. S. (2018). The effects of facial expression and relaxation cues on movement economy, physiological, and perceptual responses during running. Psychology of Sport and Exercise. 34, 20-28. https://doi.org/10.1016/j.psychsport.2017.09.009.

Harbour, E., Stöggl, T., Schwameder, H., & Finkenzeller, T. (2022). Breath Tools: A Synthesis of Evidence-Based Breathing Strategies to Enhance Human Running. Frontiers in physiology, 13, 813243. https://doi.org/10.3389/fphys.2022.813243

Svensson, S., Olin, A. C., & Hellgren, J. (2006). Increased net water loss by oral compared to nasal expiration in healthy subjects. Rhinology, 44(1), 74–77.