Triathlon Race Day – Nutrition

Considerations of Glycemic Index (GI)

Carbs are arbitrarily divided into slow-release (low GI) polymers and faster release (high-gi) examples. Sugary, high GI carbs are great for recovery from exercise as they get into the muscle faster than you can say… “ultra-endurance athlete”! However, carbs have the effect of switching-off fat oxidation; they muscle their way to the fore and become the body’s primary energy source. This is all well and good for a sprint athlete – but for triathlon we want to spare some glycogen, burn some fat, and keep a reserve of carb for when we need to make our sprint-finish! Low GI feeding prior to exercise may offer a compromise between fat and carbohydrate fuelled training…

Many studies have found Low GI meals promote FA oxidation and carbohydrate sparring in subsequent endurance exercise compared to High GI, possibly by reducing circulating levels of insulin (Coyle, 1995; Rahkila, Soimajarvi, Karvinen, & Vihko, 1980; Stevenson et al., 2006; Wee et al., 2005). This can compliment endurance training adaptations such as increased fat-burning, while still permitting high intensity, carb-dependent exercise (Girandola & Katch, 1976). In addition, Low GI foods also aid weight-regulation by inducing feelings of satiety (Brand-Miller, Holt, Pawlak, & McMillan, 2002), helping an athlete to reduce their energy intake.

On race-day, have a high-carb, low GI meal (e.g. oat-based) 2-4hr before training (aim for about 120-180g carbs. As well as low GI carbs, you may want to experiment with caffeine(the suggested dose would be 1-3mg/Kg – 180mg 45min before. Try caffeine products or a few carbohydrate-caffeine drinks before/during). In addition, look at the acute lactate strategies (bicarb) attached.

During the race…

During the race, you should keep your carb intake constantly high. Whilst exercising, the stress hormones released and the need for high-intensity output will make it unlikely that you’ll suffer from any “Carb Coma”, so high-GI sugars are the order of the day. In addition, certain high-density polymers such as vitargo and maltodextrin have a higher GI than table0sugar, meaning they may be particularly suitable.Aim to meet a carb intake of 1g per kilo per hour (e.g. 75g per hour for a 75Kg athlete). This is equivalent to sipping  500ml of a standard (6%) sports drink and consuming 1 energy bar  and eating 1 gel per hour

 Hydration is also vitally important…

It’s well known that dehydration  of as little as 1.5% body-mass can harm athletic performance, while the negative impacts increase in line with the amount of fluids lost and are worsened by exercising in the heat. Loss of salts (electrolytes) can impair cognitive function and muscular capacity. An observational study conducted by the Football Association showed that the risk of injury increases when players are dehydrated. Getting an idea of your body’s sweat rate is important so you can plan how much to carry. Salt losses also vary massively – take a look at your clothes. If you leave white patches on your hat, or dark-coloured clothing, you’re a “salty sweater”, meaning the next point is even more important…

 Add electrolytes

Now, some of you will be having too much salt in your diet and may not need a huge amount extra. However, if you’re sweating a lot, and if you’ve identified yourself as a sodium secreting sort, then salt is essential. Look to consume electrolyte containing sports-drinks, or if you’re losing loads of water, use something like a Diarolyte sachet. You should be aiming for between 10mM and 40mM solutions (look at the packet) depending on temperature.

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