Triathlon: From Olympic to Ironman


Typically seen as one of the most gruelling single-day sporting events in modern day endurance sport, Ironman® triathlons are growing immensely in popularity with athletes from all over the world, and of all physical abilities taking part. Consisting of three-phases like all triathlons, the Ironman® distances of a 3.9km (2.4 mile) swim, followed by a 180km (112 mile) bike ride, and finishing off with a full marathon distance run of 42km (26.2 mile) with no scheduled rest breaks, is no easy task, and should never be underestimated as just a swim in the ocean, as easy as riding a bike, or a run/walk in the park!

However, as alluded to in the previous article on sprint distance triathlons, there are shorter triathlon distances like the sprint distance, which then progressively lengthen up to Olympic, Half-Ironman®, and through to the Holy Grail of triathlons, the Ironman® itself. In this article, we will concentrate on the Olympic, Half-Ironman®, and Ironman® distances, and how to nutritionally prepare for these events, pre, post, and during the event.

As with all triathlons there is always a large emphasis put on the actual physicality of training due to the nature of an inclusive 3-sport event, and this is absolutely right to do so to be able to succeed. However, the stress of training for 3 separate sports can only be achieved through the correct training diet, and the necessary training adaptations will only flourish with this same training diet (1).

TOP TIP: Athletes should remember that training alone, without a well thought out and dynamic nutrition training plan, will be self-limiting!

|Pre-Race Build-Up:

For all endurance events including triathlons, there has to be an important emphasis placed on the athlete’s nutritional build-up phase. Getting this right can be the difference between having a successful swim phase, or struggling to keep up due to low energy levels, and early onset fatigue.

The rigmarole of several days of carbohydrate-loading seems to be a thing of the past among current athletes now due to the typically higher daily replenishments of glycogen through periodized carbohydrate feeding (2), and consequently, muscle and liver glycogen stores are potentially able to be fully replenished within a 24-hour period before an event (3), if stores are not totally depleted. With this in mind, competitors should aim to consume a high-carbohydrate meal (200-300g/CHO) at least 24-hours before the start of the event to help replenish glycogen stores. It would also be recommended to consume a medium-carbohydrate:protein snack such as Mountain Fuel® Night Fuel 30-40-mins before bedtime to aid in the body’s replenishment of essential nutrients including carbohydrates and proteins.

Competitors should also aim to consume, whenever possible, a medium-GI carbohydrate meal around 3-4 hours before the event is due to start to optimize glycogen stores. Mountain Fuel® Morning Fuel with oats, seeds, and coconut oil is a great option when this situation arises, and can also be paired with Mountain Fuel® Xtreme Energy Fuel to fully maximize glycogen storage and hydration levels, as the nature of long-course triathlon events, generally calls for early starts, and can unfortunately, start far too early for some athletes to be able to consume a large carbohydrate breakfast. This is considerably common on the morning of a race, so relax and just consume a snack of maybe some fresh fruit, a bottle of Mountain Fuel® Xtreme Energy Fuel, and/or as previously stated, some Mountain Fuel® Morning Fuel with a blend of oats, mixed seeds, coconut oil, and/or maple syrup, as this is a great start to any long race day.

TOP TIP: Do not make any drastic nutritional changes in the build-up phase to your event, as this will increase potential gastrointestinal discomfort, which may be carried over in to your race, and can also cause early onset fatigue if incorrect nutrient levels have not been achieved!

TOP TIP: Remember to continue periodizing macronutrients through your taper phase as well, so as not to gain unwanted weight…Fuel for the expected daily energy expenditure!!


So here you are, after weeks and months of training hard, sleeping well, and eating a nutritious, well-balanced diet to help stay fit & healthy, race day has finally arrived…you stand on the start line, nothing else you can do now…the hooter sounds!!…and your off, nutrition & hydration plans all ready…or are they?

It is well documented that endurance athletes can, and potentially should aim for the consumption of ~60g/CHO/hr as this is the reported optimal amount which can be oxidized by the body (4), however, a 2006 study found that there was a positive link to mixing the types of multiple transportable carbohydrates, such as fructose, glucose, and maltodextrins and an increased oxidation rate (up to ~90g/CHO/hr) which may lead to a delay in fatigue during exercise performance (5), yet this does involve some training of the gut to be able to take on board such high amounts of carbohydrates during physical activity, so please do not attempt this on your race day. Even with training, GI-stress can still occur, especially when taking part in such prolonged endurance events.!!

The mixture of multiple transportable carbohydrates has also been shown to be easier on the gut and decreasing the risk of any gastrointestinal issues.

Due to the nature of a triathlon event there are times when fuelling may be much more difficult than others. For example, attempting to eat during the swim phase is not ideal, however, for those competitors who are going to take much longer than others, there is the option of carrying energy gel(s) under their swim cap, or inside their wetsuit for that little extra energy to get them back to shore and on to transition one (WARNING!…consuming energy gels mid-swim must be practiced otherwise you may drown!!).

On the bike is where most of the refuelling should be done, as this is when you will typically be needing to, and it’s probably the easiest phase to actually be able to eat and consume food. Keeping glycogen levels relatively high coming in to transition two will help you stay strong through the early part of the run phase, and stave off the onset of muscle fatigue. Fuelling on the bike can be done in several ways and athletes will all have their own personal favourite, however, here at Mountain Fuel® we suggest a mixture of Mountain Fuel® Xtreme Energy Fuel drinks and solid foods such as energy bars and/or flapjacks.

TOP TIP: Try and limit the amount of solid food consumed in the final 60-90 minutes on the bike so as not to increase potential GI distress coming in to transition two!!

Throughout the bike phase of a longer triathlon event, carbohydrate ingestion should be steady and frequent (~60g/CHO/hr) to help continually keep glycogen levels as high as possible, and this is also the recommendation for the run phase too.

Hopefully, coming in to transition two, athletes are feeling well fuelled and hydrated and are ready to take on the final stage of their event…the run. Nutritional recommendations stay pretty much the same for the run phase with regards to amounts, however, this is where many athletes will change their source of energy to reduce any gastrointestinal issues to energy gels (if you can stomach them) and/or drinks, such as Mountain Fuel® Xtreme Energy which will provide ~40g/CHO from a 50g serving, and of course this may be increased at the user’s discretion. For the slower athletes in the pack who like to take a little beak during the transition period, consuming a Mountain Fuel® Ultimate Recovery shake is an ideal alternative to solid food (the chocolate flavour is out of this world!!).

TOP TIP: If consuming anything other than water becomes a problem, don’t panic, keep drinking water until you feel like eating something, if your appetite does not return then it is vital to keep drinking, reduce your pace, and just keep moving forward at a ‘comfortable’ pace!!


A solid, well-organised recovery plan, is an integral part of decreased recovery time & increased recovery ability, especially after such a demanding and exhaustive endurance event.

It is suggested that carbohydrate intake is increased to help glucose stores be restored (see Pre-race recommendations). Protein consumption should also be increased to ~1.5-2g/ to aid in whole body recovery and muscle rebuilding. Pay attention to amino acid intake especially leucine, as this is a key amino acid for muscle protein turnover regulation (see our ‘Understanding Protein’ article for lists of amino acids). All of the recommended nutrient intake increases should be done through a food first approach and through the addition of supplements when and where needed.

Here at Mountain Fuel® we really do like to boast about how wonderful our Mountain Fuel® Ultimate Recovery Fuel drinks are, with over 11g of blended whey and soy protein, all 11 essential amino acids, and flavours which are second to none, we recommend consuming one of our recovery drinks after such an event too allow the recovery process to begin. This can also be continued on a daily basis as part of a periodized protein pacing strategy to help decrease recovery time (look out for our ‘protein pacing’ article coming soon!).

“I love Mountain Fuel, particularly when I use the whole system on race days. I’ve finished the season strong with a win at the Ben Nevis Triathlon where I was able to push hard on the bike, and then smash the run!”

Chris Stirling, Triathlete, Mountain Runner, and Mountain Fuel ambassador.


1– Ryan. M. (2012) Sports Nutrition for Endurance Athletes (3rd Ed.). Colorado, USA, Velo Press

2– Haff, G.G. (2013). Essentials of Sports Nutrition and Supplements: Carbohydrates. NJ, USA, Humana Press

3 Tardie, G. Glycogen Replenishment After Exhaustive Exercise., (2008)

4– Kreider, R.B; Wilborn, C.D; Taylor, L; Campbell, B; Almada, A.L; Collins, R; Cooke, M; Earnest, C.P; Greenwood, M; Kalman, D.S; Kerksick1, C.M; Kleiner, S.M; Leutholtz, B; Lopez, H; Lowery, L.M; Mendel, R; Smith, A; Spano, M; Wildman, R; Willoughby, D.S; Ziegenfuss, T.N and Antonio, J. ISSN Exercise & Sport Nutrition Review: Research & Recommendations. Journal of the International Society of Sports Nutrition. 7:7 (2010)

5-Jeukendrup, A. E. Carbohydrate Intake during Exercise and Performance. Nutrition. 20 (7), 669-677 (2004)