Nutrition Plan for Ironman Event

Nutrition Plan

In each ironman event, the importance of having a pre-planned nutrition plan is becoming more and more evident.

There are several examples in which we witness elite triathletes reporting that they were in the best physical capacities of their lives, but that even so, they could not even complete a race.

And fatally, in the vast majority of cases, the problem is always the lack of a nutrition plan strategy to face these Ironman competitions.

But now, you will understand everything it takes to have the best nutrition plan for an Ironman event

Physiological and Nutricion Plan Demands of an Ironman Race

Your body stores contain roughly 500 grams of carbohydrate (this is 2000 kcal), not enough to make it to the finish line. In theory it should be enough to get most athletes through the first 3 hours of a 4 to 7 hour race but topping up from the start is essential. Because it takes time for carbohydrate to be absorbed, you need to start early with fuelling to make sure you avoid carbohydrate depletion. Once you run out of carbohydrate stores it is difficult to recover.

Muscle glycogen and blood glucose are the most important substrates for the contracting muscle. Fatigue during prolonged exercise is often associated  with muscle glycogen depletion  and reduced blood glucose concentrations and, therefore, high pre-exercise muscle and liver glycogen concentrations are believed to be essential for optimal performance. However, the Scientist Tim Noakes recently suggested that it is unlikely that muscle glycogen depletion  ‘alone’ limits prolonged exercise performance. Using a simulated Ironman triathlon model, Noakes predicted that after 4.5 hours of cycling at an estimated exercise intensity of 71% maximum oxygen consumption (VO˙ 2max), an elite male Ironman triathlete would have almost completely depleted his or her carbohydrate (CHO) stores. Interestingly, after completion of the 180km cycle, elite triathletes are able to run at a speed of 16 km/h for another 160 minutes, which represents an exercise intensity of >66% VO2max.

In addition to glycogen depletion, dehydration can also impair endurance performance. The loss of body water will result in a reduction in plasma volume, stroke volume, and skin blood flow, which can lead to an inability to maintain thermal homeostasis and reduced performance. Therefore, the nutritional challenge is to replace body water and prevent fatigue. Severe hypohydration may reduce the rate of gastric emptying while increasing the likelihood of gastrointestinal (GI) problems, therefore, hypohydration may become a self-perpetuating problem. Most importantly, while hypohydration and hyperthermia alone have negative effects on performance, their combination is particularly serious, both in terms of performance and health.

Therefore, let’s more directly identify which main nutrients and minerals we should take into account when preparing our nutrition plan strategy for an Ironman.



magnesium pills

Magnesium is an essential mineral that demands attention when it comes to health assessment into a nutrition plan. It is required by virtually every cell, and it’s vital in more than 300 chemical processes that sustain basic human health and function,  including muscle contraction and relaxation, nerve function, cardiac activity, blood pressure regulation, hormonal interactions, immunity, bone health and synthesis of proteins, fats and nucleic acids. Thus a shortfall of magnesium can limit energy production, leading to fatigue, lethargy, reduced power, muscle twitches or cramps. Athletes in particular might find it easy to explain away fatigue or muscle cramps, lowered immunity, and even altered heart rates, and indeed these symptoms are common and multi-faceted in cause. Aside from being used up in the production of energy, magnesium might also assist performance by reducing accumulation of lactic acid and reducing the perception of fatigue during strenuous exercise through its action on the nervous system. The recommended daily allowance for the general population is a minimum of 300 to 350 mg for women and 400 to 450 mg for men. Research suggests that endurance athletes can safely consume 500 to 800 mg daily, and there is debate as to whether this amount should be higher still.



As we head into months of hotter weather, it’s especially important for triathletes to pay special attention to individual sodium levels when preparing a nutrition plan for racing. The key is to figure out your distinct sweat rate (read on) and replenish your salt stores appropriately. It’s much easier to stay ahead of salt loss rather than try to play catch-up during a race or long workout. Here are five tips for keeping your sodium levels in check:

1. Be sure to include salt in your diet before competition in all distances to maintain blood sodium levels. Serious salt loss leads to low-sodium levels called hypnoatremia. Symptoms range from muscle cramping and swelling of fingers and toes to headache and disorientation. Extreme cases can be life-threatening.

2. Take a minimum of 600-1,000 mg of sodium per hour if you’re female and 800-1200 mg of sodium per hour if you’re male. Aim for the high end of these ranges for longer events.


Glycerol is a 3-carbon tri-alcohol. It is a colorless liquid, with a sweet taste, odorless and viscous. 

Glycerol is present in foods as a component of dietary fats derived from plants or animals. It’s safe for human consumption! 

Oral glycerol intake can be used to facilitate better retention of ingested fluids, which may be beneficial for athletes in sports where hydration status may be compromised due to prolonged and/or intense exercise in thermally challenging environments. 

  Glycerol-induced hyperhydration can be used to increase the athlete’s ability to tolerate fluid loss and compensation, that is, to delay, prevent, or mitigate the deleterious effects of dehydration that can occur during exercise.

Glucose Regulation

It may well be one of the most impactful variables when we think nutrition plan for training and performance. Yes, your body is an incredible machine. And like most machines, it’s powered by fuel.You’ve probably learned (maybe the hard way?) that you can’t just feed your body any kind of fuel at any given time. To attain and sustain performance at any level, you need the right fuel at the right time. Which brings us back to: GLUCOSE. When you eat or drink something, the available glucose in that substance is either used for immediate fueling demands or is stored for future use.

Training the Gut

The gut of those who play endurance sports needs to be trained!!!

It is very common to hear complaints related to bowel function from triathletes and marathon runners, especially during long training sessions or on competition days, indicating that gastrointestinal (GI) function is not always ideal in these situations.

Endurance exercise performed exhaustively may be associated with lower blood perfusion in this tissue because there is a redistribution of blood flow to the exercising muscle, compromising the absorption of important nutrients for the maintenance of prolonged exercise. The gastrointestinal tract (GIT) plays a critical role in providing carbohydrates and fluids during these exercises and can therefore be a major determinant of performance.

  So how to solve this problem?

The GI tract is highly adaptable, that is, it is possible to “train” the athlete’s intestine to receive the best nutrients and liquids, avoiding these discomforts during sporting events, with improved performance. Gastric emptying, as well as stomach comfort, can be “trained” and the perception of fullness diminished.

Evidence also shows that diet impacts the gut’s ability to absorb nutrients.

Ex.: A high-carbohydrate diet will increase the density of glucose transporters in the intestine, as well as the activity of that transporter, which allows for greater carbohydrate absorption and oxidation during exercise.

When the athlete’s intestine is not adapted to receive a greater amount of carbohydrate, what usually occurs are osmotic diarrhea, as this carbohydrate present in the intestine without proper absorption pulls water to the organ’s light, causing diarrhea. In addition, there may be bloating from fermentation caused by intestinal bacteria.

Therefore, training the bowel must also be part of the nutrition plan!



It appears caffeine enhances performance in shorter events through four interrelated neuromuscular effects:

  1. Lowering the threshold for muscle recruitment.
  2. Altering excitation contraction coupling.
  3. Facilitating nerve impulse transmission.
  4. Increasing ion transport within muscles.

In longer events, caffeine delays fatigue by reducing the athlete’s perception of effort. It increases the concentration of hormone-like substances in the brain called ß-endorphins during exercise. The endorphins affect mood state, reduce perception of pain, and create a sense of well-being.

Caffeine has also been found to delay fatigue during exercise by blocking adenosine receptors on fat cells. As a result, caffeine increases the level of free fatty acids in the bloodstream and thereby increases fat burning during exercise.

Caffeine is commonly used by endurance athletes 30 to 60 minutes before races to enhance competitive performance. The ergogenic effect of caffeine is dose-dependent. The maximum effect is seen with doses of 5 to 6 milligrams per kilogram of body weight. For a 150-lb runner this translates to roughly 340-400 mg, or the amount of caffeine you’d get in 14 to 17 ounces of drip brewed coffee. The minimum amount of caffeine the average runner must consume for a measurable ergogenic effect is about 2 mg per kilogram of body weight.

It makes less sense to use caffeine as a daily workout performance enhancer, for two reasons. First, workouts are seldom maximal efforts. Second, the ergogenic effects of caffeine consumption decrease with habituation. For this reason, if you are a regular coffee drinker, you should cease coffee consumption four to six days before participating in a race.

More information about caffeine, you can find here.

Carbohydrates during Training

When we think of Ironman race, triathletes  rely heavily on carbohydrates as a fuel source, which will be stored later as muscle and liver glycogen.

It is important to highlight that for training shorter than 45 minutes, it is not necessary to consume it during practice. For those from 60 to 150 minutes, 30 to 60g of carbohydrates per hour of exercise are recommended, and up to 90g for over 150 minutes.

In practice, it is always important to pay attention to individuality, so it is interesting to start with the minimum quantities and increase according to needs and tolerance. In this sense, supplements such as sports drinks and carbohydrate gels are more practical and typically more tolerable options for the athlete to consume during training. Those who prefer can opt for solid foods.

However, if the exercise exceeds 150min, the intake of 90g (there are already cases in the literature of 120g) per hour and in this case, mixing carbohydrate sources (glucose + fructose), can be a good strategy. This is because the body has the ability to oxidize up to 60g of glucose per hour, so, therefore, different sources are used in order to prevent gastric discomfort.


Leave a Reply

Your email address will not be published. Required fields are marked *

plugins premium WordPress