IRONMAN 70.3® Chattanooga

Mike carb-loaded in the two days before the race, hitting ~7.3g of carb per kilogram of bodyweight each day, which falls just short of the 8-12g/kg recommendations. He might want to consider adding a PF 60 Chew Bar as a snack each day as this would have helped him hit the recommended dose and further optimised his glycogen stores ahead of the race. Mike’s carb-rich breakfast three hours before the start would have replenished his liver glycogen stores which deplete overnight, putting him in a good position going into the swim.

Mike’s strategy for the bike centred around three super concentrated bottles of Carb & Electrolyte Drink Mix; each 750ml bottle packed 105g carbs to provide him with an average intake of ~95g/h during the bike section. This large amount of carbs created a hypertonic solution meaning that the glucose concentration in the fluid was higher than that of the blood which means water is drawn into the gut for digestion. This is worth noting as hypertonic solutions can be useful in exercise situations where a large amount of carbohydrate is required quickly and fluid intake is not an issue, but in hot conditions like this, they can cause the bloating and GI distress that Mike reported. In future, he would benefit from either decoupling his fuel and hydration by relying on more solid fuel sources like gels and chews for his carb intake, and using his fluids for hydration. Or he could reduce the concentration of his bottles by mixing the Carb & Electrolyte Drink Mix as instructed (3 scoops per 750ml) and supplementing with gels or chews.

Despite the discomfort he was experiencing, Mike managed to maintain ~50g carb per hour during the half marathon through PF 300 Flow Gel and three energy gels from aid stations. This will have helped him reach the finish line in Chattanooga.

With the temperature exceeding 30°C (86°F) for most of the race, staying on top of his hydration was a key focus for Mike. His average fluid intakes of ~1L/h on the bike and ~842ml/h on the run would likely have replaced an appropriate proportion of his losses in the heat. Similarly to his fuel, the concentration of this fluid is where Mike could improve upon. Mike has a known sweat sodium concentration of 1250mg/L and so should aim to replace sodium at a similar relative concentration to avoid building up a sodium deficit. The bottles on Mike’s bike, however, had a relative sodium concentration of ~2,333mg/L and the concentrated flasks of PH 1500 he carried on the run were at ~3,000mg/L. This also draws fluid into the gut, which compounded his GI issues. Mike’s average relative sodium concentration was not extreme in absolute terms as he did dilute some of these drinks with plain water from aid stations, but in future he would benefit from maintaining a sodium concentration closer to his losses across all of his drinks.

Mike had three caffeine gels from aid stations on the run to hit ~3.64mg of caffeine per kilo of bodyweight which sits within the 3-6mg/kg recommended dose for a race of this duration. This would have supported his mental alertness and perception of fatigue through the toughest phase of the race. If he was looking to further benefit from caffeine, he could consider an earlier dose of the stimulant by taking one PF 30 Caffeine Gel halfway through the bike because caffeine takes ~45 minutes to peak in the bloodstream, and has a half-life of 4-5 hours.