The science behind Kilian Jornet's feats

GenevaIn the latest edition of the Ultra Pirineu mountain race, more than 1,300 runners gathered in the Cadí mountain range to cover more than 100 km of distance and 6,600 meters of elevation gain. Extremely demanding events like this make us question the limits of the human body, as well as the role that physiology, nutrition, and rest play in achieving good athletic performance and, in general, enjoying a healthy life.

Answering these questions was one of the objectives ofKilian Jornet's latest challenge, called Alpine Connections, which he completed in August and during which he surrounded himself with a scientific team to understand his physical and mental state in detail. After having climbed more than 170 peaks in the Pyrenees in just eight days last year, this year the renowned athlete climbed 82 peaks over 4,000 meters in the Alps in just 19 days. In total, he covered a distance of more than 1,200 km in two weeks, a feat clearly within the reach of very few human bodies and minds.

Throughout the project, Jornet was accompanied by a team of physiologists who measured various physiological and mental parameters. The team, consisting of Jesús Álvarez-Herms, PhD in biology and biomedicine and a professor at the University of the Basque Country, and Sergi Cinca, a health and high-performance sports advisor, provided essential support to successfully overcome the challenge.

"Throughout the challenge, we've been measuring many parameters to try to understand what happens physiologically, metabolically, and cognitively during this type of effort," explains Jornet. "The interesting thing is that we can use a challenge of this magnitude to understand how the human body reacts," he adds.

 

The body adapts to find balance

The human body is a very complex system. Its functioning depends on a large number of physiological functions that allow the body to adapt to the changes that occur during sports practice, within the individual thresholds that define each athlete. Parameters such as body temperature, for example, are essential for studying how different stimuli promote imbalances in certain thresholds, such as those that occur during intense physical exertion.

"What the body does for its survival, without differentiating between competitions and extreme efforts, is try to keep the thresholds of these physiological parameters stable," says Cinca, who was present throughout the Alps challenge.

"There may be several parameters that are altered and that affect this balance, such as temperature," continues this expert, adding that "we call them life-or-death thresholds, since they are the parameters that, if destabilized, the organism enters a state of protection that endangers its integrity."

Understanding how the body adapts is essential not only for planning good physical preparation for highly demanding competitions, but also for understanding what it means to be healthy. "Dr. Álvarez-Herms has developed a methodology to improve athletes' performance and also their health. From his perspective, peak performance cannot exist without systemic health," says Cinca.

Although the physical aspect is essential to achieving these types of challenges, the psychological aspect is equally, if not more so. In fact, after a great effort like running a marathon, not only does the entire body need to recover, but a good mental and emotional recovery is also crucial. "After a major goal, there's always this period of mini-depression, especially in projects like this, where there's a lot of cognitive work and risk management," Jornet confesses.

During the Alpine challenge, Cinca and Álvarez-Herms also collected data on the runner's cognitive state to assess the effects of fatigue and optimize preparation and rest. "Kilian has an exceptional mental capacity, with decisive resilience and focus. But he loves doing what he does," explains Cinca, adding that "from the top of the mountains, Kilian feels liberated from everything."

An unconventional diet

One of the key factors in both athletic performance and overall health is nutrition. Beyond the classic recipe for a balanced diet, elite athletes follow dietary protocols that can be very strict to achieve peak performance in competition. However, one of the main conclusions drawn from the Alpine challenge is that traditional dietary protocols are not necessarily optimal. "I ate a lot and a lot of things," says Jornet, "I spent about 8,500 calories a day."

The way Jornet approached the latest challenge in the Alps differs significantly from how he did in the Pyrenees. "The main difference has been, above all, in managing his nutrition, sleep, and recovery," the athlete explains. "For example, in the Pyrenees I ate every few hours, while in the Alps we tried to eat less often, but in larger quantities and with certain types of food."

During the latest challenge, the athlete followed his usual vegetarian diet and avoided processed pasta and sports supplements. "However, he had the best performance ever in a test of this nature, and this is because we respected all of Kilian's physiological processes, from his circadian rhythms to his microbiota," Cinca explains.

Thanks to the close monitoring of runners' physiology through the analysis of their biochemistry, genetics, body fluids, capillary blood, urine, saliva, feces, and respiratory gases, physiologists provided a series of recommendations that were far removed from the . "There were days when we determined that they should go out on an empty stomach when they had a 40-hour trek ahead of them. Or we would tell them, 'Today you will drink water with vinegar,'" Cinca explains.

The intestinal microbiota, a key piece

One of the key factors in how nutrition affects athletic performance and overall health has to do with the gut microbiota. "It's a very relevant field for improving health and athletic performance," says Álvarez-Herms. The microbiota is the set of microorganisms—primarily bacteria, but also viruses, protozoa, fungi, and yeast—found primarily in the last section of the large intestine and, in a symbiotic relationship with the body, aid in the digestion of food and the processing of hormones and complex carbohydrates.

The population of approximately 40 trillion bacteria that comprise it has been forged over millions of years of evolution and is unique to each of us, which means that not everyone digests food equally. "In Kilian's case, we've seen that fat metabolism is much more important than carbohydrate metabolism, and this standard is far from, for example, the current generic recommendations for sports nutrition," says Álvarez-Herms.

Another interesting example of how microbiota affects performance in long-distance events is found in a study conducted by a team of researchers from Harvard University in 2019. This study analyzed the microbiota of runners in the popular Boston Marathon. In the corresponding analysis, they found that the bacterial population was very similar among the athletes, indicating its influence on athletic performance and subsequent recovery. In this case, they analyzed how the microbiota varied before and after the athletic event. The researchers discovered that the concentration of a type of bacteria called Veillonella increased significantly after the race. The primary function of this bacteria is to process lactic acid, which is produced in large quantities during intense exercise and causes muscle fatigue.

The researchers tried to introduce Veillonella in mice and observed that their performance was 13% higher than that of mice not given this substance. This discovery opened the door to the use of probiotics, bacteria with specific health benefits, as a substance to improve athletic performance. In any case, these probiotics can not only be useful for elite athletes but can also help improve the health of some people with metabolic disorders such as diabetes.

Each body is unique beyond genetics 

Proper preparation and nutrition are essential for good athletic performance. However, genetics play a fundamental role and can determine the success of an athlete's career. However, we now know that genetics is not as decisive as it was a few decades ago. Since the discovery of epigenetics, we have learned that the way genes express themselves depends largely on the external factors each person encounters. Therefore, physical trainers have also begun to integrate epigenetics to direct genetic expression toward specific performance goals.

"We work with athletes for two to four years, because there are epigenetic changes that don't manifest themselves in the way we're interested in until this period," Cinca explains. "And that requires a lot of patience on the part of the athlete, and on our part as well," he adds.

In Jornet's case, "although he has better genetics than most people, he's not extremely exceptional," he says. "What makes the difference is epigenetics. Growing up in a mountain environment has shaped his physiology and adaptive capacity," he adds.

Jornet's Alpine challenge represents an unprecedented human feat. Thanks to the scientific monitoring it has undergone, a vast amount of data has been collected, which will be analyzed in detail to draw further conclusions. "Interesting insights for the entire population can be extracted regarding nutritional management and the management of physical and cognitive exertion, as well as recovery," Jornet concludes.

"Scientific evidence can bring about a paradigm shift in health and sports sciences. Every person can reach their full potential if properly stimulated, based on their age, lifestyle, and motivation. This requires individuality, patience, and knowledge," Cinca concludes.