The popularity of ultra-endurance triathlon races (3,8 km swimming, 180 km biking, and 42,2 km running) has increased since the first Ironman was held in 1978. Due to their long duration, one of the main goals of athletes and coaches is to optimize ergogenic aids throughout the race with the aim of improving performance.
For this, it is essential to know what the energy expenditure is in this type of test, since based on this a nutritional plan will be designed during the race in order to maintain a correct energy balance and thus avoid a drop in performance, in addition to safeguarding the athlete's health.
Early studies from 2000 estimated an energy expenditure for an Ironman of between 8.500 and 11-500 kcal 1–3. One of them even distinguished by gender, calculating an expenditure for men of 10.036 kcal and for women of 8.550 kcal. In addition, it calculated the caloric intake, being only 3.940 kcal for men and 3.115 kcal for women, which translates into an energy deficit of 60% 2. A 60%!
With the aim of updating this data and shedding light on new nutritional strategies, a new study published in 2015 4 in addition to calculating energy balance, analyzed performance data and classified macronutrient intake.
The average time in which they completed the test was 12 and a half hours, with 69% of the total time in Zone I (below the aerobic threshold), 22% in Zone II (between the aerobic and anaerobic threshold), and 9% in Zone III (above the anaerobic threshold). This only confirms that for most of the test the intensity is low (137 bpm on average), so the main fuel used is fats.
The average caloric intake was 3.643 kcal, while the energy expenditure was 11.069, resulting in an energy deficit of 67%, corroborating the data obtained in previous studies. During the test, the triathletes lost an average of 4,3 kg, that is, 5,7% of their body weight. For an athlete to lose more than 4 kg of weight with an energy deficit of almost 70% will surely result in a decrease in performance, so counteracting this loss with the help of an appropriate nutritional strategy will be crucial.
The high energy deficit is explained by the low caloric intake when compared to the high energy demands required by an Ironman. Of the total intake, 90% corresponded to carbohydrates, around 900 grams. When athletes decreased the rate of CH intake, performance decreased, which confirms that a proper nutritional strategy is crucial in long-duration endurance events. Additionally, a key element is the nature of the carbohydrates, since the combination of different types (glucose, fructose, and maltodextrin) optimizes their oxidation and performance during exercise.Although it is difficult to estimate the ideal ratio (1:1:1) during the test, varying the type of food (gels, bars, fruit, drinks, etc.) during the test can help achieve an optimal balance.
Table 1. Macronutrient intake during a triathlon test 4
As has been proven, in this type of ultra-endurance tests, athletes work at a low % of VO2max, so their body mainly uses fat as fuel. Since energy intake does not meet the energy demands necessary to deal with a test of this type, an increase in caloric intake through fats could be a key element in sports performance, as long as carbohydrate intake is not reduced and gastrointestinal tolerance is not compromised. The athlete, together with his coach and the help of a nutritionist, should establish a work plan in order to increase fats throughout the test, being essential to train this aspect so that on the day of the test, gastrointestinal problems do not become a headache.
Therefore, it will be necessary to design an adequate nutritional strategy that is in line with the energy expenditure of each athlete. If it is possible to reduce the energy deficit, the athlete will be able to maintain performance for a greater part of the event. Additionally, knowing that fats are the main fuel once glycogen stores are depleted, one of the main objectives of training should be for the athlete to improve the oxidation of these during long runs.
REFERENCES
- Laursen, P. B. & Rhodes, E. C. Factors affecting performance in an ultraendurance triathlon. Sports Med. 31, 195–209 (2001).
- Kimber, N. E., Ross, J. J., Mason, S. L. & Speedy, D. B. Energy balance during an ironman triathlon in male and female triathletes. Int. J. Sport Nutr. Exerc. Metab. 12, 47–62 (2002).
- Kreider, R. B. Physiological considerations of ultraendurance performance. Int. J. Sport Nutr. 1, 3–27 (1991).
- Barrero, A., Erola, P. & Bescós, R. Energy balance of triathletes during an ultra-endurance event. Nutrients 7, 209–22 (2015).
AUTHOR
Adrián Castillo García
Master's degree in Integrative Physiology (UB)
Degree in Physical Activity and Sport Sciences (UPM)
University specialist in Personal Training
Writer at FISSAC
