Olympic Games: behind every sporting performance there is a scientist

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Nutrition for high-level athletes, the first step towards the Olympics

“At a very high performance level, even a dietary detail can play a role”, supports Alain Carpentier, head of the biometrics and nutrition applied to exercise research unit. Himself a former high jump athlete, his teams evaluate the body composition of athletes, their nutritional program and the food supplements they ingest depending on the sport practiced.

“The athlete will have to record everything he eats in quantity and quality for a week to make a complete assessment, and do urine analyzes to monitor his protein excretions by muscle breakdown.“, he explains. To rebuild, the muscles need proteins that the athlete ingests in his food or through dietary supplements. “Animal proteins are assimilated three times faster than plant proteins, which requires particular vigilance among vegetarian athletes.“, adds Alain Carpentier.

Nervous impulses and muscular command, the two facets of performance

Its teams are part of the ULB CAPS, which includes the metabolic, psychological, biomechanical, isokinetics and injury prevention, neuromuscular and nutritional centers. “By moving from the field to the laboratory, we can standardize efforts and standardize performance, then modify these conditions across large numbers of people to retrieve reliable information in real time”explains Stéphane Baudry, researcher in the Applied Neurophysiology Research Unit at ULB.

In his laboratory, researchers can analyze the two neuromuscular components of a high-performance movement: the nerve impulse that leaves the brain and its execution by the muscles. “Initially, the performance gain comes more from nervous factors, then with chronic training of muscular and nervous factors together“, specifies Stéphane Baudry. Muscle mass and tendon elasticity, important for sports performance, are dissected by MRI or ultrasound.

The results must then be related to the characteristics of the athlete and the sport practiced. “The stiffer the tendon, the more force it transmits to the bone segment”, explains Jacques Duchateau, from the Teaching Unit in Theory and Practice of Physical Education at ULB. A stiff Achilles tendon will, for example, benefit more from high jumping, while running will benefit from more flexibility. The skier, whose Achilles tendon is preserved in his shoe, will on the other hand have a particularly rigid patellar tendon while that of the middle-distance runner will have it much more flexible.

Scientists can even pinpoint which muscles fatigue first and therefore need to be strengthened during the athlete’s training. To do this, he or she is placed in conditions close to the actual practice of his or her sport, while muscular activity is examined by electromyography, via electrodes placed on the skin. “This technique has, for example, been used on Grand Prix motorcyclists. It has made it possible to see that certain arm muscles fatigue more quickly, to target preparation to make them more resistant, for example when braking”illustrates Stéphane Baudry.

Oxygen: consume less to produce more

To fuel muscular performance, athletes must also optimize their cardiovascular system and therefore their oxygen supply. “The main marker of physical fitness is maximum oxygen consumption, also called VO₂max“, or the maximum volume of oxygen that the athlete is capable of consuming, explains Vitalie Faoro, professor of Physiology and Biomechanics of Movement at ULB.

“By training, the athlete can increase this VO₂max and thus achieve superior performance for the same level of effort and oxygen consumption.” A trained athlete will thus be able to achieve a VO₂max of 60 mL of oxygen per minute and per kg, compared to 40 for a regular athlete and 20 for a sedentary person. By then optimizing their movement to save the energy spent, the athlete can even continue to improve their performance, through what Vitalie Faoro calls “the economy of gesture”. This is particularly what enabled marathon runner Paula Radcliffe to continue to improve despite a VO₂max stable around 70 mL/min/kg.

Briton Paula Radcliffe beats her own world record in 2 hours 15 minutes and 25 seconds by crossing the finish line of the London marathon on April 13, 2002. Credits: NICOLAS ASFOURI / AFP

Risks of injury and wear and tear on the heart, the health of athletes is monitored

An outperformance that is not without risk. “In athletes, the heart is larger and in particular the right heart responsible for expelling blood loaded with oxygen. They must be monitored over the long term to avoid heart problems such as rhythm disturbances and ventricular fibrillation.“, points out Vitalie Faoro. The sports most at risk are endurance sports such as cycling or football, she illustrates.

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In general, the health of high-level athletes is closely monitored, as the risk of injury is high. “With each running step, the ground returns approximately 2.5 times the person’s weight after impact“, says Véronique Feipel, vice-dean of the Faculty of Motor Sciences at ULB. The nature of the competition also changes the situation, with five to ten times more risk of fractures in the final due to the pressure and fatigue generated.Fatigue increases injury risk, as do equipment, nutrition, injury history“, lists Véronique Feipel.

Alain Carpentier particularly warns athletes against dehydration, the primary cause of poor performance. Logical, when we know that muscles are made up of 73% water, compared to 60% for the whole body. “Losing 2% of water means lowering your performance by 5 to 10%. he warns. With a lifestyle as strict as that imposed by high-level athletes, it is not so surprising that 62% of athletes develop EDs (eating disorders). However, the weight should not drop too much. “Being underweight can lead to stunted growth, injuries, weakened immune system and chronic fatigue.“, lists Alain Carpentier.

Every athlete is different

If targeted training helps minimize these weaknesses, the equipment can also play a role. “For example, we use starting blocks with force sensors to optimize starts.“, reveals Jacques Duchateau. At the start of the competition itself, the spacing and inclination of the blocks and their advancement behind the starting line can also be modified, he adds. “An athlete with low push and acceleration and a long reaction time to the start signal thus obtained a gain of 50 milliseconds in reaction time“, he remembers.

An improvement that can make all the difference. Hurdle jumper Jonathan N’Senga also became champion, notably by improving his performance on the starts, using a starting block position.which athletics specialists would have found doubtful, but which was the best for him!“, concludes Jacques Duchateau.

As competitions approach, the two to three annual visits by athletes to performance support centers like that of the ULB become more frequent and the precision of the tests increases. At the Olympic games, “the slightest mistake can be costly.”recognizes Alain Carpentier.