Getting your nutrition right – what you eat and when – will have a big impact on your race result. Obviously this is more important the longer the triathlon, so its important for all athletes to spend time thinking about and (hopefully!) practicing before race day to minimize the risk of GI distress or bonking (fun, but not in the tri context!).

Nutrition and hydration are very individual: what works for one may not work for another. Much comes down to your own physiology, the course and conditions, palatability, (in)tolerances and race duration. Think about each of these aspects; as well as aid station provision (and whether you’ll use it). Training and racing are times for learning and refinement. Use your brick and longer sessions (especially those with race pace effort), and shorter B races to test what works.

Race day nutrition needs to be seen in the context of an overall race nutrition plan. In my view, this should include: your strategy in the preceding days, race morning, during the event and post-race recovery. Here I will focus on race day itself.

Although ironmans start early it is vital to take on board some pre race fuel. I would suggest eating a breakfast of approx. 600-800 calories about 2.5hours before race start. This meal should be rich in carbohydrates and low in fibre. I eat finely granulated rice (found in the baby food department) – add boiling water, some tahini/cashew butter and honey. Simple! A bagel/English muffin/white toast – with jam and maybe some smooth peanut butter, and a banana are also good options. Porridge can be ok, if you opt for the lower fibre variety. Aim to sip on some fluid, but don’t over hydrate.

During an ironman your body is focusing on powering your arms and legs, and less on buffet consumption. You can flood your stomach with food, but there’s no guarantee of digestion (although digestion is enhanced if you are going at a more sedate pace, especially on hiller courses when you may also be sitting more upright). The easiest and best time to fuel and hydrate is on the bike. Sip some water in T1, and take some time at the start of the bike to settle into a rhythm before trying to consume calories. I’d consume roughly 1.5g carbs per kg of body weight per hour on the bike, and 1g of carbs per kg on the run. Alternatively think about ingesting 250-300 calories and 200-250 calories per hour on the bike and run respectively.

Solid v’s fluid (energy drink) fuel really is a matter of personal preference. I would suggest a mix of both, with some semi-solids (gels). A sport drink should have: water, carbohydrate calories and electrolytes (sodium, potassium, magnesium and calcium). I don’t believe protein is necessary during a race. For carbs, a mix of simple sugars is best: so glucose (also called dextrose) and fructose. A simple sugar is easily digested and by mixing two types you increase the amount your body absorbs. Once you know a) your carb/calorie needs per hour and b) how many carbs/calories you have in a drink bottle, you should be able to calculate what percentage of the bottle to consume per hour (clear bottles are good so you can see the fluid inside). Don’t over consume plain water. It can leave you bloated and dilute your electrolytes leading to hyponatremia (water intoxication or low sodium). On the subject of sodium, you are a heavy sweater and feel you need extra sodium, I would dissolve extra in your sports drink, rather than take (very concentrated) salt tablets whole. I use Cytomax, which has the right balance and mix of simple sugars, as well as electrolytes.

Fuel can also come from semi solids, such as gels (2 gels = roughly 200 calories). I wouldn’t rely exclusively on solids, but ingesting some is fine – especially if you are going at a slightly ‘slower’ pace. I’d save burgers for post-race, and stick to easily digestible and transportable foods. Avoid anything too fibrous or excessively chewy. Good options are: bananas (often provided at aid stations), non-nutty chocolate bars (I have one bite of a chocolate bar an hour on the bike), jellies or gummies, (chocolate covered) pretzels, rice krispie squares or even (white bread) sandwiches with jam. If you wanted you could even make your own rice balls – cooked white rice, with honey or melted marshmallow/chocolate to stick it together.

If you do take on solids, do it in the first ¾ of the ride. Any later and you’ll still be trying to digest it on the run, which isn’t always easy. If you do feel stomach discomfort it’s often best to ease off your pace, before it’s too late.  If you have any special nutritional requirements make sure that you have back-up sources in transition and special needs bags.

On the run, I take one gel every 25mins, washed down with some water. I would avoid solids during the marathon, unless you find yourself walking with a glowstick. Coke is OK, but once-you-pop its hard to stop, so leave this for the last 7-10km – or if things get very messy and you feel a bonk coming on.

Obviously the conditions play a huge part, and what is palatable/digestible in cold conditions may not be so at 35 degrees with 90% humidity.

However hard you try it really is difficult to replicate a race nutrition strategy in training. Yes, you can practice and prepare. But sometimes races throw you curve balls, or GI dynamite, that you least expect. Not everything will go perfectly. There will be discomfort, problems and challenges that you may, or may not, have predicted. Back up strategies help, but ultimately your body can sometimes behave in a way that you’d never have anticipated. It took me six ironman races to develop a nutritional strategy that didn’t leave me running for the bushes/lava fields.

Remember though, that whatever happens there will be a burger, pizza, kebab and a huge plate of chips waiting for you at the finish line. Race day food at its very best! Good luck!

(thanks go to Professor Asker Jeukendrup who taught me much of what I now know about race nutrition and also Rebecca Marshall for some of the photos below)