Energy balance of 10 male and 8 female triathletes participating in an Ironman event (3.8-km swim, 180-km cycle, 42.2-km run) was investigated. Energy intake (EI) was monitored at 7 designated points by dietary recall of food and fluid consumption. Energy expenditure (EE) during cycling and running was calculated using heart rate-V̇O2 regression equations and during swimming by the multiple regression equation: Y = 3.65v + 0.02 W − 2.545 where Y is V̇O2 in L · min−1, v is the velocity in m · s−1, Wis the body weight in kilograms. Total EE (10.036 ± 931 and 8570 ± 1014 kcal) was significantly greater than total El (3940 ± 868 and 3115 ± 914kcal, p < .001) formales and females, respectively, although energy balance was not different between genders. Finishing time was inversely related to carbohydrate (CHO) intake (g · kg−1 · h−1) during the marathonrun formales (r=−.75, p < .05), and not females, suggesting that increasing CHO ingestion during the run may have been a useful strategy for improving Ironman performance in male triathletes.
N.E. Kimber is with the Department of Human Biology and Nutritional Sciences at the University of Guelph, Guelph, ON, Canada Nl G 2W1. J.J. Ross is with the Human Sciences Division at Lincoln University, Canterbury, New Zealand. S.L. Mason is with the Animal and Food Sciences Division at Lincoln University, Canterbury, New Zealand. D.B. Speedy is with the Department of General Practice and Primary Care at the University of Auckland, Auckland, New Zealand.