Nutrition For Half Ironman Triathlon

I'm a 49 year old woman who is just starting out to train for a half Ironman triathlon, which is 9 months away.

I'm very confused about the nutrition side of it. There's so much info out there, I don't know where to begin. I would like to know at this stage exactly what I should be taking before, during and after a training session of an hour or more.

For example should I be drinking any plain water, or should it be all sports drinks and should the sports drink include carbohydrate? There are also gels and some of these even include caffeine. Are gels beneficial over liquids? Can you recommend any brands?

I would really appreciate some advice in this area, many thanks.

Intelligent Triathlon training replies:
Nutrition does indeed have the potential to be a complicated area, mainly because, as you say, there is so much differing advice out there, and so many different products available.

The longer the duration of your race, the more important nutrition becomes. So it is important, particularly for race day, that you get this right.

Before Training:
If you are doing a hard session, you won’t want to have eaten too much, especially if it is a run session where your stomach gets bounced up and down a bit more!

However you do need some fuel, therefore you can either train a couple of hours or so after a meal, or if the gap will be longer, aim to have a small, easily digestible carbohydrate-rich snack about 2 hours beforehand.

As you are preparing for an endurance event, fat utilisation is very important. You can improve your body’s ability to use fats as a fuel by doing easy sessions on an empty stomach (ie first thing in the morning), or if you need to eat, after a high fat/protein, low carb breakfast.

Don’t attempt a hard session in a fasted state, as the lack of carbohydrates will impact negatively on the quality of session you are able to do. Training in a fasted state can take a little time to adapt to, so if you feel awful the first time you try it, give it a few more goes and it should get better!

During Training:
For sessions lasting up to around an hour in duration, that are not high intensity and in weather conditions that don’t make you sweat excessively it is fine to have water only if you need a drink.

For longer or harder sessions, or if you sweat a lot (particularly if you are a very salty sweater – if your sweat dries leaving salt crystals on your skin you are a salty sweater) then consuming electrolytes is beneficial.
If the session is easy, you might get away with just an electrolyte drink to replace the salts lost in your sweat (Nuun tablets are excellent for this, as just one example).

Or even just water (or nothing), if you don’t sweat much. The best guide is your thirst – there is nothing to be gained from drinking more than your sense of thirst guides you to drink.

For longer or harder sessions, you will need some carbohydrate.

This can be in any form that suits you – many people find gels digest better than liquids, but it really is just a case of trying a variety of options to see which suits you best.

Different types of carbohydrate are able to be used at different rates. Ones that can be used quickly include glucose and sucrose, whilst slower ones include fructose and galactose. Ensuring your carbohydrate source contains a mixture of types, always including fast ones, optimises the amount of carbohydrate your body can use.

The general advice for exercise of 2.5 hours or longer is to take 90g of mixed carbohydrates per hour. For 1 – 2.5 hours 30 – 60g is usually sufficient.

After Training:
You should aim to take on board some carbohydrate and protein as soon after the session as possible, particularly if it was a high intensity or long session.

With regards quantities, the calories required depends upon your weight and the duration and discipline of training. A moderate 60-kg female may burn a maximum of 600-800cal per hour in a really high intensity, full on session or 250-400 for a steady aerobic session. The difference would be that those <400 would be mainly fat and easily replaced; the >600 would be mainly carbohydrate and need quick replacement.

If you want more detailed information about carbohydrates for sport, read this review paper by some very well respected sports nutritionists.

So To Summarise:

* Before Training:

A high-carb snack a couple of hours before the session (exact timing depends on how your stomach copes with digesting the food).


An easy session in a fasted state.

*During Training:
Depends on duration of session and how much you sweat but general guidelines:

Energy drink, gels or equivalent (eg candy/sweets like jelly beans etc) for harder or longer sessions – 90g of carbohydrates per hour if 2.5 hours or longer, 30 – 60g if 1 – 2.5 hours.

Water or electrolyte drink for easier sessions.

*After Training:
Easily absorbed carbohydrate snack (high glycemic index) or meal as soon after training as possible, with some protein. Replace lost fluids if sweated a lot.

The most important thing is that you practice with a range of products, timings, quantities etc to find out what suits you. Make sure you don’t try anything new on race day. The science is there to guide you but everyone is different!

You can find more general advice on our nutrition pages.

Comments for Nutrition For Half Ironman Triathlon

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Dec 02, 2013
by: Anonymous

The answer to the question is very informative and easy to understand, just what I needed.

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