Energy Metabolism During Ironman Triathlon: Different Horses on the Same Courses.

Adapted from a Paper by Maunder, Kilding, Daniel J. Plews. 

Leading experts in Endurance/Triathlon training stratgies.

Ironman triathlons are basically ultra-endurance events of various length duration. The Athletic/fitness or performance level of those competing varies dramatically, with elite competitors finishing in  rather fast times +/_8 hr's and lower performing amateurs finishing in +/_12-14 hr's.  A combined effort over three distinct aerobic disciplines : swimming, cycling and running. Many experts in this area  have demonstrated that the absolute energy cost of these events is high, and the rate of energy expenditure increases in proportion with the athlete’s competitive level. Given the finite human capacity for endogenous carbohydrate storage - 600-800g Glycogen, (1-2hrs) vs Fat adapted (Unlimited Hrs-Days).  It's logical therefore to minimize the carbohydrate cost and maximizing fat use at competitive intensities.  A range of strategies exist that may help to achieve this goal, including, but not limited to, adoption of a low-carbohydrate diet, exogenous Ketone supplementation and/or periodised training with low CHO availability.  The Ironman triathlete  should  consider adopting metabolic strategies to minimise the endogenous carbohydrate cost associated with exercise at competitive intensities. Specifically, periodised training with low carbohydrate availability combined with exogenous Ketone supplementation GoKeto during competition would be ideal  for elite and top-amateur Ironman triathletes who elicit very high rates of energy expenditure. Conversely, the adoption of a low-carbohydrate or ketogenic diet is also welcomed for most performance amateurs as it enhances numerous functions such as training ability/consistency & recovery.  The events place  high energy requirements so that given high rates of fat oxidation rates are favorable over limited Carbohydrate storage capacity to match the energy demands required. 

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 Maximal Fat Oxidation is Related to Performance in an Ironman Triathlon

October 2017 International Journal of Sports Medicine