Ironman races represent an extreme effort for triathletes. The physiological stress and energy demands depend on the athletes' level, varying dramatically according to their profile. For example, in the Frankfurt Ironman of 2017, times ranged from 7 hours and 41 minutes of the winner, to 14 hours and 56 minutes of the last classified.
The absolute expenditure in an Ironman race can exceed 10.000 kcal, and the energy rate (kcal/min) increases as the athlete's competitive level rises. An elite triathlete with a time in an Ironman of 8 hours and 4 minutes would expend about 9.626 kcal, that is, around 20,1 kcal/min. A top-amateur, with a time of 9 hours and 6 minutes, would have an expenditure of 9.062 kcal, 16,6 kcal/min. In contrast, a very amateur triathlete would finish in 13 hours, expend 10.425 kcal, and their energy rate would be the lowest, 13,3 kcal/min.
Given the limited capacity that people have to store carbohydrates, minimizing their depletion during competition should be a goal in Ironman preparation. Due to the different energy rate depending on the competitive level, the same guidelines cannot be established for a triathlete who finishes an Ironman in 8 hours as for one who does it in 14. Conducting training sessions with low carbohydrate availability and increasing their supplementation during the competition can be a good strategy for elite triathletes.In contrast, those with lower performance (>12 hours), following a low-carbohydrate diet can help reduce the use of endogenous CH, as fats can almost completely meet the required energy demands.
AUTHOR:
Graduate in Physical Activity and Sport Sciences, Official Master in Integrative Physiology, University Specialist in Personal Training, NSCA – CPT.
