Physiological Considerations for Success in Ironman Distance
Triathlon
Ironman triathlon is one of the most gruelling one-day endurance events in sport. The
primary determinant of success in ironman triathlon racing is the ability to produce and
efficiently utilise large amounts of energy over a long period of time [1]. For this to occur
there must be training induced physiological adaptations to the cardiovascular, metabolic,
thermal and musculoskeletal systems of the body. In order for a high rate of energy
expenditure to occur without creating fatigue, these systems must be working at their
3
optimal capacity in order to maintain homeostasis [1]. Researchers have found key
physiological variables correlate with endurance performance. These include maximal
oxygen uptake (VO2 max), economy of motion and the fractional utilisation of oxygen
uptake (VO2) [2]. These measures become less relevant for events lasting in excess of 4
hours where the physiological demands of the event become extremely high. Factors such as
fluid and electrolyte balance and hydration and glycogen status play a significant role in
determining performance outcomes. These external variables can have a greater effect on
performance in endurance events than other physiological measures such as VO2 max or
submaximal VO2 [3].
This review will discuss the nutritional challenges that face the ironman triathlete.
In order for a high rate of energy
expenditure to occur without creating fatigue,