Patterns of Brain Activity During Breathlessness in Athletes

What's the science?

Being an athlete can affect the body in many ways, but how does it affect brain function? For example, in high performance endurance athletes the brain may adapt to perceive or control breathing differently. This week in NeuroImage, Faull and colleagues used fMRI to understand how brain networks might differ during breathlessness in endurance athletes versus sedentary individuals.

How did they do it?

Twenty endurance athletes and twenty sedentary individuals participated. While undergoing fMRI, participants rested as well as completed a task in which they learned to associate shapes shown on a screen with periods of upcoming breathlessness (in order to measure changes during anticipation of breathlessness). The sensation of breathlessness was created by applying inspiratory resistance via a mouthpiece. One shape always predicted upcoming breathlessness, while another shape always predicted upcoming unrestricted breathing. Participants rated how difficult the previous stimulus was (0-100%) after each trial, and how anxious it made them feel at the end of the experiment. The authors used a general linear model to analyze the anticipation of upcoming breathlessness and anticipation of no upcoming breathlessness, among other factors. They measured functional connectivity – a metric that captures how activity from different brain regions fluctuates together over time – between breathlessness brain networks in athletes.

What did they find?

There were no differences in average anxiety or breathlessness intensity perception between groups, nor group average brain activity in any task. However, during anticipation of breathlessness, the activity in athletes’ brains in regions of the salience (a network involved in salient events) and sensorimotor (a network involved in touch and movement) networks (including the anterior insula and primary motor cortex, among others) was proportional to how intense they were going to find their breathlessness in an upcoming stimulus. This relationship was reversed in sedentary subjects, where their brain activity was negatively proportional to their upcoming breathing sensations. Furthermore, while individuals were at rest (not performing the task), there was greater connectivity between the salience/task-positive brain network (active when paying attention to an important stimulus such as breathlessness) and the primary motor cortex in athletes. 

                                      Brain,  S  ervier Medical Art,  image by BrainPost,  CC BY-SA 3.0

                                     Brain, Servier Medical Art, image by BrainPost, CC BY-SA 3.0

What's the impact?

This study identifies a network of brain regions that positively predict breathlessness in athletes but negatively predict breathlessness in sedentary individuals - thus certain brain networks are altered in athletes. The salience network was found to be differently connected in athletes versus sedentary individuals, which may indicate that functional connections between brain regions are also altered in these athletes. This work could be used to understand breathlessness in clinical conditions in the future, where exercise is prescribed for treatment.

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Faull et al., Cortical processing of breathing perceptions in the athletic brain. Neuroimage (2018). Access the original scientific publication here.