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Guide: Tackling an Ironman Triathlon - Nutrition Plan

February 22, 2017

Tackling an Ironman triathlon: How to get the nutrition you need to succeed

An Ironman is one of the most demanding endurance experiences available, composed of a 2.4 mile swim, 112 mile bike ride and a full 26.2 mile marathon to finish!  On July 17th, hundreds of people will head to Bolton for this year's headline British Ironman event.

The Ironman name alone is enough to underline how this is not a challenge that you can just turn up to - months of preparation are needed. Even if you're an avid cyclist or a triathlon enthusiast, this mammoth trial requires peak fitness – and one thing that's crucial to Ironman success is an optimised diet, both before and during race day.

To get the best understanding of the diet needed to succeed, Ribble Cycles spoke to Annie Simpson, an expert nutritionist from OTE Sports, to find out what is needed to take on this all-day feat.


In both training and on the day, Ironman athletes must have a set meal in place, as drastic changes can have different impacts on the body. Simpson explains that the best breakfast is one high in carbohydrates, with a portion of protein to help slow digestion and avoid starting-line hunger.

"By eating two to three hours before the start, food will be given enough time to settle in the stomach," she adds.

Simpson's example breakfast includes: •    One large bowl of porridge made with milk, with chopped banana or dried fruits and nuts (with extra protein from Greek yoghurt); •    A glass of fresh fruit juice for calories and hydration; and •    A cup of coffee, to help wake up for an early start.

Before the triathlon Simpson continues: "In the time between breakfast and the race, focus on hydration. Sipping a hydration tab little and often in the days and hours before the event ensures you start the event fully hydrated.

"As little as 2% loss in body weight as a result of dehydration can affect sporting performance. Don’t start the race on the back foot this way."

A light snack before the event is also a good idea; options include: •    An energy bar •    A jam sandwich •    A banana

In-race tactics Simpson was keen to stress how in-race nutrition is by far the most important factor at play – and that 60 to 90g of carbohydrates need to be eaten each hour. Based on a ten-hour Ironman, this means that the average athlete needs 700g+ during the race.

"Our body stores carbohydrates in our muscles and liver, but these are limited and are used up during exercise," Simpson continues. "Without sufficient carbohydrates stores, the intensity we can perform at decreases dramatically. In Ironman, you need to keep stores topped up."

Using OTE Sports' range as a basis, Simpson puts forward a standard plan to follow during Ironman UK, based on the 700g carbohydrate target:

•    6 x energy gels (120g of carbs); •    5 x caffeine gels (100g); •    2 x energy bars (80g); and •    5 x energy drinks (400g)*.

*800ml mixed with 80g of energy drink in the bottle.

Here are Annie's top tips for the average Ironman race: Swim     Required: •    1 x energy gel

"It is very difficult to fuel during the swim, so aim to have an energy gel ten minutes before the start," she says.

Transition 1 Required: •    1 x energy gel •    Water

Before getting on the bike, Simpson recommends a gel and quick mouthful of water; the most part of an athlete's pannier is consumed while riding.

Staff member Dee on a Ribble Aero TT

Bike Required: •    4 x 800ml of energy drinks •    2 x energy bars •    2 x energy gels •    2 x caffeine gels

"Spread the intake evenly, and don't go for long periods without sipping your drink," she asserts. "Aim to consume half an energy bar or gel every 30 minutes, saving caffeine gels for the later part of the ride."

Staff member Mark on Ribble R872. Photo by Ellen Isherwood - Lancs Racing Scene

Transition 2 Required: •    1 x energy gel •    Water

As with the first transition, the build up to the run requires the same intake.

Run Required: •    2 x energy gels •    3 x caffeine gels •    1 x energy drink •    Water

Simpson once again recommends an even split of intake, adding how important it is to have water from feed stations, particularly on hot days.

After the race After completing an Ironman triathlon, it shouldn't simply be a case of resting up. The total calories consumed during one such race is in the region of 6,000 to 8,000kcal. Despite the above nutrition, a racer will be left in a calorie deficit.

Special drinks can aide recovery; these contain protein for rebuilding muscles, carbohydrates to replenish your energy stores, and fluid to aid rehydration.

As such, a congratulatory pat on the back for finishing must be swift, Simpson says: "As soon as the event finishes, it is important to go into recovery. Aim to drink this within 30 minutes of finishing – this is the 'window of opportunity' to kick-start the recovery process. You may not want to consume this, but it is a case of needs must."

Your tips Have you got any experience of Ironman UK or other long-distance trials? Let us know your top tips in the comment section.