Triathlon Nutrition: Use carbs when the time is right

Decide your goal and you’ll know how much carbohydrate you need, says Dr Kevin Currell.

There’s been plenty of publicity around carbohydrates lately and it’s hard to know whether to eat lots of it or none at all. It seems you have to be in one camp or another, and it’s certainly a topic that provokes passionate debate. The starting point should be to differentiate between carbohydrates’ potential role in obesity and their role in sports performance. In obese populations where little exercise is undertaken, carbohydrate needs are minimal and can potentially be provided through naturally occurring sources such as fruit and vegetables. However, sports performance is a different animal. Here the aim is to go fast, no matter what distance your event. In this case it is clear that carbohydrates are the body’s fastest fuels.

In pure biochemical terms, carbohydrate is your body’s first choice for fast energy. The biochemical process of burning carbohydrates is called glycolysis and this process produces energy at a far faster rate than beta oxidation, the biochemical equivalent for fat. Indeed, if we reduce carbohydrate intake in the long term the evidence is clear that our ability to sprint during endurance exercise is diminished, because of changes to enzymes in the muscle.

In response to this though, if we feed high amounts of carbohydrates in all training sessions then we inhibit adaptations in fat metabolism. For endurance events this is a key adaptation to training. So in terms of triathlon training, what should you do? Well, if the aim of a training session is to go long and slow then minimise your carbohydrates intake. If the pace is above threshold or you are doing quality interval work, then carbohydrate is king.

On race day, carbohydrates are most certainly crucial. Fatigue will occur because of a drop in blood sugar or depletion of muscle glycogen. Both of these are carbohydrate stores and therefore need to be replenished. A pre-exercise meal containing carbohydrates is key. This, along with 60-90g per hour of simple carbohydrates (yes, we’re talking about sugar) during exercise, will improve performance. This has been proved time and time again in scientific research.

So are carbs good or bad? As usual the answer depends on what you’re trying to do. It is never black or white. If your over-riding aim is weight loss and prevention of obesity then maybe they are bad. However, if you want to go fast in a triathlon or any other sport, they are most definitely good.

Team Talk: Reaching the Top

“Beware ‘silent evidence’ when reading about what others eat. With another plan, they could’ve been even better.” Phil Mosley Coaching editor