Finding the best triathlon race-day nutrition to maximise your energy is essential for your best performance. We guide you through the key fuel sources.

Mastering race-day nutrition is an essential element of the sport for every triathlete for both racing and training. Choosing the right sources of fuel can mean the difference between storming down the finishing chute high fiving the crowd and succumbing to dizzying weakness and never reaching your goal.

Your body’s energy stores

The body can store roughly 90-minutes’ worth of glycogen, the natural fuel used by your muscles while you exercise. While the amount of glycogen your body can hold will increase a little as your strength and fitness improve, this essentially means that you’re going to need to top up your energy for anything longer than a 90-minute training session or sprint-distance triathlon.

Fail to keep on top of your energy reserves and you risk the dreaded ‘bonk’ – an energy-depleted state where you completely run out of physical and mental steam, characterised by jelly legs, zero power and dizziness.

The body can store roughly 90-minutes’ worth of glycogen

While the amount of energy your body can store is similar to the next athlete bobbing around the water at the swim start, differences in the gut’s ability to break down the fuel, whether it sits well on your stomach or even just the taste of it can play a big role in how effective your race nutrition is. That’s why it’s important to experiment with what works best for you in training and your race-day nutrition.

What sources of fuel?

For the majority of athletes, the main source of fuel is carbohydrate, which comes from most sports nutrition as some form of sugar. When ingesting these sugary carbs, the body creates insulin to help break them down and convert them into glycogen or fat.

The speed at which the body digests these high-glycemic carbs and provides energy to hungry muscles is what makes them ideal to keep you performing at your best when training or racing hard.

The quality of the carbohydrates does matter, however. As a rule of thumb, the lower the ratio of sugar in the carbohydrates, the more stable the flow of energy will be and the longer it will last. By contrast, something like cola will cause a fast sugar rush but with the inevitable crash afterwards.

Race-day nutrition options

With so many sports nutrition companies all making energy gels, bars, drinks and a host of other energy sources – not to mention adding real food into the mix – finding the best combination for you can take time and a lot of trial and error. To help you in your research, here’s a breakdown of some of the best options for race-day nutrition.

Energy drinks

Energy drinks usually come in powder form, allowing you to mix your preferred concentration by adding water. Ingredients tend to include a mix of maltodextrin (a sweet, easy to digest and carb-rich substance derived from maize or corn), and fructose (fast-digesting fruit-derived sugars). In short, it means a lot of carbs and a blood sugar spike to keep energy levels up when training and racing hard.

Energy drinks come in many different flavours, formats and recipes so you are bound to find something that suits you. (Photo: Triathlon Vibe)

Some drinks may also contain electrolytes to help keep sodium levels from becoming too low or diluted, helping to avoid dehydration or hyponatremia. However, it’s important to check how much you’ll actually be getting from the nutritional info to work out if you’ll need an additional electrolyte source, especially when racing in the heat.

  • Pros:
  • Easy to drink and digest
  • An ideal source of fuel on the bike
  • More hydrating than other fuels
  • Customise your concentration
  • Cons:
  • Tricky to carry on the run


Energy gels have long been a favourite fuel source for endurance athletes and it’s no wonder considering that they have a liquid consistency that’s easy to swallow and give a good hit of carbohydrates. On the downside, they can sometimes be a bit fiddly to open and it’s very tricky not to end up with sticky fingers afterwards!

Gels typically use similar ingredients to energy drinks but have a thicker consistency for a more concentrated energy hit. However, this can mean some athletes find they don’t sit on the stomach as well.

Energy gels
Energy gels can take a little getting to use to and are not for everyone but they can provide good energy hit in an easy to carry form. (Photo: Triathlon Vibe)

Due to their concentration, you’ll need to follow a gel with plenty of water to help process the energy in the gut. To mitigate this a little, some gels are also designed to be isotonic – featuring a similar concentration of sugar as naturally occurs in the body, usually through added water – for easier absorption in the gut. However, in our experience, you’ll still want to add a water chaser to your gel, no matter its isotonic credentials.

There are also plenty of gel options containing caffeine, which are a great way to pep you up when you start to flag in longer training sessions or races.

  • Pros:
  • Easy to carry on the bike and run
  • Good energy hit in a small package
  • Lots of flavours to keep nutrition interesting
  • Convenient with minimum prep
  • Caffeinated options
  • Cons:
  • Have to be taken in one go
  • Need to be taken with water
  • Can cause issues for sensitive stomachs
  • Can be difficult to open quickly
  • Sticky!

Energy bars

Energy bars are designed to give you a good hit of high-quality calories – mostly carbs and little protein – in a chewable format. Recipes usually minimise fats and fibre to avoid slowing down digestion while many also contain sodium to help maintain electrolyte balance.

Energy bar
Energy bars are a halfway house between liquid sports nutrition and real food giving you high energy in a chewable format. (Photo: Triathlon Vibe)

Ingredients often include whole grains such as rolled oats and while these complex carbs require more effort to digest, they give a more sustained release of energy.

There are a wide variety of brands out there all with varying flavours, consistencies and recipes, so experiment with a few different types in training before committing to your race-day nutrition plan.

  • Pros:
  • More sustained source of energy
  • Can be broken into smaller pieces
  • Cons:
  • Often chewy or dry, so hard to swallow
  • Harder to eat at high intensities
  • More energy needed to digest, diverting blood from muscles

Energy sweets

For those who prefer their energy delivered in bite-sized chunks, energy sweets such as Clif Bloks or Jelly Belly Sport Beans pack in plenty of easily digested carbs – as well as some electrolytes – in chewy form.

Race-day nutrition option - energy sweets
Energy sweets are great additions to other sources to top up in easy to chew and tasty formats. (Photo: Triathlon Vibe)

This is great for running, where popping them inside your cheek to chew on can be easier than necking a whole gel between breaths. They’re also perfect to take in-between your regular feed intervals on the bike if you get hungry.

  • Pros:
  • Great for eating little and often
  • Taste like sweets
  • Easy to eat when breathing hard
  • A great addition to other fuel sources
  • Cons:
  • Can be more difficult to calculate intake
  • You’d need a lot if they were your main energy source

Real food

No matter how energy-concentrated or metabolically efficient sports nutrition is, for many athletes – and especially Ironman competitors – there comes a point where enough is enough and even the thought of eating anything more makes you feel sick. To avoid getting to that point in the first place, it’s important that you actually like the taste of your sports nutrition and this often means forgoing a little bit of science and choosing your favourites for your race-day nutrition.

picking something you enjoy means you’re more likely to feed properly

From savoury choices like honey-salted cashews or peanut butter wraps to sweet treats like cut-up Snickers or chocolate-centred breakfast bars, having a mix of different options in your nutrition bag can stop your appetite from turning against you. It might not be formulated in a lab but picking something you enjoy means you’re more likely to feed properly and take on enough calories to get you to the finish line.

  • Pros:
  • Tasty and less sickly
  • More choice and flavours
  • Helps avoid appetite being curbed
  • Cons:
  • Hardest to digest, diverting blood from muscles
  • Not packaged for race day use
  • Harder to eat at high intensities
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