About two months ago, on August 13^th, top class swimmer Michael Phelps won his 23^rd Olympic gold medal overall in the men’s 4 x 100 m medley relay in Rio de Janeiro. It was his 5^th gold medal during the Rio games, a storybook comeback of the world’s most successful Olympic champion of all time. I had to imagine where he keeps all these medals and how incredibly huge his trophy case has to be. But then I looked at the white wall in my small flat… no trophy case, no medals. Man, what am I doing wrong?

Of course, I don’t dedicate my whole life to sports as he does, spending every day in the swimming pool to achieve top performance. His way to success seems to be built on hard physical exercise and on his brilliant technique. Undoubtedly, beyond these two, success in high-performance sports is based on a combination of many factors: genetics, teamwork, tactical preparation, form of the day. Some “sportsmen” even use prohibited substances like erythropoetin (EPO) or meldonium, the recent fashionable pharmaceutical, to pimp up their blood cells and vessels. And if that doesn’t help, a magnanimous bribe or well-planned betting fraud might.

Sports “between our ears”

Another crucial factor in high-performance sports is mental strength. To access their top performance at the exactly right time in important competitions, athletes have to handle stress, enormous pressure, fear and unfamiliar circumstances. This is why more and more professional psychologists are consulted and involved in many different disciplines of competitive sports.

“Competitive golf is played mainly on a five-and-a-half-inch course… the space between your ears.”¹ As the former golfer Bobby Jones states correctly, mental processes happen in the athlete’s brain (of course). But what exactly does he mean by this catchy metaphor? And which mental processes do I even refer to? As you will see, overcoming psychological obstacles like the ones I mentioned before is just one of many tasks for our brains during sporting activity.

A more scientific view

As valuable and experience-driven Bobby Jones’s opinion might be, I don’t want to rely merely on athletes’ quotes when writing about the meaning of neuronal activity in sports. Well, I could, and it might even be funnier but I think it is a better idea to see what empirical science has to say!

First of all, mental processes that need to be taken into account for top performance accomplishment in sports are, for example, motivation², selective attention³, goal setting⁴, working memory⁵ and decision making⁶. All these processes also happen “between our ears” – in the command center in our head – and contribute to our performance in various ways.

Second, and this might often be overlooked, our brain controls motor execution as well. When bending your leg to kick a football or stretching your arm to dynamically dive into water, the respective motor areas in your brain are active and constitute the cause of these actions⁷.

This already shows the important role the brain seems to play in sporting activity. Nevertheless, there are rather few studies linking neuroscience and sports science.

The waves in your brain

That may be one reason why Dr. Guy Cheron from Brussels University and his colleagues decided to attack the issue with a scientific publication earlier this year, not without a little dig: “These relatively small amounts of studies dedicated to sports compared to the large total number of […] studies raises serious questioning with regard to the interest in sports in the scientific community”⁷. Just to be clear: they’re not saying that all scientists are lazy but rather that there is a lack of applying neuroscientific findings in the context of sports! This is why, in their paper, they review already existing results, show how to record neural activity associated with sports and how to find neural correlates of performance. A clever method might be high-density electroencephalography (EEG) recording which could be able to provide quantitative feedback to athletes and coaches⁷.

EEG represents complex signals that depict electric neural activities in the brain. The frequencies of these signals form different kinds of brain waves – yep, your brain kind of creates waves! – the characteristics of which are highly dependent on the degree of activity of the brain’s cerebral cortex (the outer layer)⁸. In order to make the terminology a little more respectable and appropriate for serious professional discussions, our neuroscience predecessors decided to distinguish these waves by frequency and gave them relatively boring names in terms of Greek letters.

How are brain activity and performance related?

Dr. Cheron and his colleagues argue that we don’t know a whole lot about sports from a neuroscience perspective, but what do we know? Here a few examples of what we have found so far⁷:

• Sleep is known to be involved in motor learning: While we are sleeping, fast EEG signals between 13 and 15 Hz (so-called spindes) improve the consolidation of newly learned motor sequences and thus their later retrieval.
• Stimulation of some areas in the left prefrontal cortex of our brain facilitates implicit motor learning in a golf putting task… (maybe I was wrong and THAT is what Bobby Jones was talking about?!)
• Another relevant brain area for sports is the hippocampus because it is crucial for strategic spatial navigation (some cell types there are even called place cells, head-directions cells or border cells).
• Better performance in expert golfers is associated with higher EEG theta and alpha power compared to novices. Furthermore, theta activity correlates with movement acceleration.
• Chronic engagement in exercise and aerobic fitness is linked to increased attentional resources and greater cognitive processing speed. In EEG, this is shown by the P3 component, a positive peak in the signal at around 300 milliseconds after a stimulus appears. The more you exercise, the larger the amplitude and the shorter the latency of P3 becomes.

The last bullet point is especially interesting because the same effect was observed for acute physical activity, which means right following or during exercise. But before you start registering for the next marathon now just to improve your cognitive skills, let me tell you that only moderate intensity exercise appears to be advantageous! So the best thing may be something between Ironman Triathlon and 15 minutes of Pokémon Go.

Additionally, like so often in science, we have to be careful with the results. Scientific publications on EEG recordings during acute physical activity are very rare; the technical problems are not negligible. Out of these problems the main obstacle for a direct application of EEG to movements in sports is so-called movement artifacts. Wait, what!? Artifacts? Ancient Greek stuff again?

Not really: in EEG, movement artifacts are error signals which mess up the reading of the waves of brain activity. That’s why participants in most EEG experiments shouldn’t move during the recording. A possible solution would be a system incorporated in each electrode in order to measure the actual movement artifact and subtract it from the real EEG signal. But this is still more dream than reality.

Brain activity as a biomarker?

Nevertheless, Dr. Cheron and his research group did their best and summarized five EEG biomarkers hierarchically, classified by the number of corresponding functions⁷. Very briefly, biomarkers are structures or processes that can be measured in the body (for example with EEG) and influence or predict the incidence of an outcome or disease⁹. In our case, the outcome is not a disease but sports performance.

It is important to note that this figure is a first attempt to summarize already existing findings in order to define biomarkers for sports performance. Unfortunately, we can’t draw direct practical conclusions due to mismatches in the various studies concerning the sports of interest, the paradigms and analyses they used, and the interpretation of the respective results⁷.

Let’s hope that more and more neuroscientists will become motivated to build on Dr. Cheron’s work and to overcome technical problems so that we can get a clearer picture. However, if the diverse intensities of brain activity are really linked to the respective functions like shown in the figure, it would be interesting to measure the different waves in athletes like Michael Phelps – I bet you could surf on some of them…

But I don’t want to end with a bad joke like that – instead, I would like to highlight that the effects of physical activity on EEG signals are observed across all age groups. As we learned in Polina’s blog post from last week, engagement in sports and aerobic fitness can have important benefits across the human lifespan from an increase of cognitive performance in children and adults until attenuating cognitive decline with age⁷. And the even better news is: you don’t need to have one single gold medal for this.

References

1. Jones, B. Bobby Jones Quotes at BrainyQuote.com. BrainyQuote (2016). Retrieved from http://www.brainyquote.com/quotes/quotes/b/bobbyjones391177.html
2. Pedersen, D.M. Intrinsic-Extrinsic Factors in Sport Motivation. Mot. Skills 95, 459–476 (2002). http://doi.org/10.2466/pms.2002.95.2.459
3. Arjona, A., Escudero, M. & Gómez, C. M. Updating of attentional and premotor allocation resources as function of previous trial outcome. Rep. 4:4526, 1–9 (2014). http://doi.org/10.1038/srep04526
4. West, R. L. & Thorn, R. M. Goal-setting, self-efficacy, and memory performance in older and younger adults. Aging Res. 27, 41–65 (2001). http://doi.org/10.1080/036107301750046133
5. Dipoppa, M. & Gutkin, B. S. Flexible frequency control of cortical oscillations enables computations required for working memory. Natl. Acad. Sci. U. S. A. 110, 12828–33 (2013). http://doi.org/10.1073/pnas.1303270110
6. Renfree, A., Martin, L., Micklewright, D., & Gibson, A. S. C. Application of decision-making theory to the regulation of muscular work rate during self-paced competitive endurance activity. Sports Medicine, 44, 147–158 (2014). doi:10.1007/s40279-013-0107-0
7. Cheron, G. et al. Brain Oscillations in Sport: Toward EEG Biomarkers of Performance. Psychol. 7, 246 (2016). http://doi.org/10.3389/fpsyg.2016.00246
8. Sawant, H. K. & Jalali, Z. Detection and classification of EEG waves. J. Comput. Sci. Technol. 3, 207–213 (2010). http://doi.org/10.1016/j.infsof.2008.09.005
9. WHO, International Programme on Chemical Safety, (2001): Biomarkers In Risk Assessment: Validity And Validation (EHC 222). Retrieved from http://www.inchem.org/documents/ehc/ehc/ehc222.htm

Head figure: Sports in the brain (CC0 1.0)