The Fatmax stress test and the athlete’s type of energy metabolism
13 May 2019

An article published in the scientific journal Medicine & Science in Sports & Exercise has shown that a FATMAX stress test on professional footballers not only provides cardiovascular fitness levels, but also helps to understand the players’ main energy metabolism. Understanding this variable in more depth may be very useful for personalising nutrition and the type of sports drinks athletes should consume.

This study of 16 players is a result of the collaboration between Barça Innovation Hub and the Gatorade Sports Science Institute (GSSI). Doctors Xavi Yanguas and María Antonia Lizarraga, from the medical staff of the first division football team, are two of the article’s authors.

As Dr Yanguas explains, “the FATMAX test is an incremental stress test on a treadmill in which the speed is increased every three minutes and the incline is also increased in the final stages. The athlete starts the test walking and ends it after reaching a state of fatigue. The athlete wears a mask, and the oxygen inhaled and carbon dioxide exhaled are analysed as the test progresses. A curve is obtained with the ratio of the gases, which gives a profile that demonstrates whether the athlete uses carbohydrates or fats as his main fuel source.”

Surprising Results

In the authors’ opinion, the results have been surprising, as the theory until now indicated that carbohydrates were absolutely necessary because they were the universal fuel for all athletes.

“However, we have seen that in team sports – particularly with elite footballers – what stands out is that there are many more with a ‘fat burner’ profile. They use this fuel as the main energy substrate for exercising and reserve carbohydrates for moments of greater physical effort”, states Lizarraga.

Another interesting aspect after repeating the test over successive pre-seasons, the individual profile of each footballer does not change: those who metabolise fat continue doing so the following year. While it is true that an athlete may optimise his consumption of fats, he will always be a fat burner. And the same thing happens with the carbohydrate metaboliser and with those called “intermediate burners”, who burn both fat and carbs.

Personalise Nutrition

Understanding this metabolism may help personalise different nutrition strategies. As Dr Yanguas explains, “If, for example, a player uses carbohydrates as their main fuel source for exercising, they will need sports drinks for hydration which will also provide carbohydrates that they can use effectively. However, a footballer who burns more fat will not need as many carbohydrates, and will require sport drinks with lower concentrations of carbohydrates”.

For Asker Jeukendrup, former Global Senior Director of the Gatorade Sports Science Institute, it is essential to carry out “more studies of this kind to better understand why there are such large differences between individuals and if these differences mean that nutrition advice should be different.”

For this reason, research is also being carried out on the Club’s basketball, futsal, Barça B, and women’s football players. The results will be published shortly.

Link to the original article (in English)

The Barça Innovation Hub team


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