For me, performance nutrition centres around three key areas:

  1. Optimising performance.
  2. Ensuring optimal recovery.
  3. Maintaining optimal health.

When it comes to working with endurance athletes, there are plenty of factors that need to be considered when addressing these three points. None more important, nor more debated than carbs.

Before diving into what we need to consider when it comes to carbohydrates, I feel it’s necessary to quickly cover why carbs are essential for endurance athletes, specifically addressing the above points.


When it comes to optimising performance, we’re really looking at combatting potential factors that can cause fatigue. The main reason we train is to force the body to adapt to be able to maintain a faster pace for a given distance or to run/cycle/swim further or longer. Fatigue is the principal barrier to this. It’s what causes us to slow down or stop during a run. Carbohydrate availability for the working muscles is one of the primary factors that limit performance. In fact, there is solid evidence to suggest that performance in prolonged, sustained or intermittent exercise is enhanced by maintaining high carb availability. Thus, carbs play a vital role in optimising performance for endurance athletes.

It’s also important to remember that our body’s carbohydrate stores are relatively limited. So, when we’re racking up the kilometres and not consuming enough carbs, our muscles glycogen tanks are slowly depleting. Low glycogen levels are associated with reduced work rates, impaired skill and concentration, and increased perception of effort.


As briefly mentioned above, when overall energy intake and carbohydrate intake is less than the amount we’re using for daily life and exercise, our body’s stores are going to slowly deplete. Acutely, if we don’t consciously take actions to replete these stores, by chowing down on carbs, then there’s a pretty good chance you’ll find yourself tanking on your next big run.

For endurance athletes’, restoration of liver and muscle glycogen stores should be a fundamental recovery goal between sessions, especially during periods when exercise volumes are high or the individual is training multiple times per day.


We also know that carbohydrates play a large role in our overall health. Not just due to their capacity to provide essential vitamins, minerals and fibre, but also due to their impact on immune health. Despite my best efforts, I’m yet to find a way to increase my clients 5 k split while watching Friends re-runs, wrapped in a cocoon on the couch, eating chicken noodle soup, nursing a cold.

Research has shown that after prolonged, high-intensity exercise there is an acute reduction in our bodies immune function. Carbs help to mitigate this effect, potentially keeping our immune systems functioning at their best.

What do I need to consider when it comes to my carb intake?

A lot of the general recommendations for carb intake fit for the endurance athletes amongst us. However, due to your goals, we can be slightly more nuanced here.

How much carbohydrate should I be consuming?

It depends. Much like the general population, carb intake for endurance athletes is still going to be highly individual. This is why you should either be monitoring your diet pretty closely or have a qualified practitioner help you.

In general, we can make the broad statement that if you’re participating in a decent amount of endurance type exercise, you’d benefit from a more moderate to high carb diet. In recent years, we’ve seen the rise “fuelling for the work required” which, as its name suggests, means titrating your carb intake based on:

  • The goal of the session. Are you aiming to maximise performance and beat PB’s? Or are you looking to achieve specific adaptions or get some kilometres in the legs?
  • The duration. How long is your session? Over or under 60 minutes?
  • The intensity. Are you running at a comfortable pace or pushing it?

For maximising performance (trying to beat PB’s), running for over an hour or running at a relatively high intensity, then you’ll want to have high carb availability (high levels of liver and muscle glycogen).

Going for a more leisurely jog, keeping the intensity down, or trying to increase your bodies ability to use fat for fuel?  Then carbs aren’t as vital.

Key Takeaway: Carbohydrate intake is highly individual and should be based on your overall goals, the goal of the particular exercise session, its duration and its intensity.

What kinds of carbs should I be consuming?

The majority of your intake should be based around minimally processed carb sources. Things like whole grains, potatoes/tubers and fruits. However, there is a place for simple carbs within the diet of an endurance athlete or aficionado. When would you consider simple carbohydrates?

  • During high volume training periods, when total carbohydrate needs are increased. Trust me, consuming enough carbs from purely whole food sources can be particularly tough when carb needs are greater during high volume training periods. Utilising easily digestible, simple carbs during these times is a much easier (and more comfortable) way to hit total carb needs and won’t affect overall health as long as the diet still contains mostly nutrient-dense foods.
  • Around and during exercise sessions. Including simple carbs in your pre-, during- and post-workout snacks/meals is a great time to incorporate them. It allows us to go into the session with adequate fuel but without feeling overly full due to a high fibre, high volume meal. It’s also less likely to result in digestive issues. During and post-exercise our muscles are more sensitive to incoming carbs, with research showing that carbs consumed shortly after a workout speed up glycogen replenishment.

While the foods you consume around your sessions should be specific to you (see training the gut below), choosing carb sources that are low in fat, fibre and protein are likely safer options. Things such as:

  • white bread with jam
  • crumpets with honey
  • bananas
  • rice cakes
  • gels
  • sports drinks
  • cereal
  • lollies

Key Takeaway: Base the majority of your carb intake around minimally processed options but consider using low fibre, simple carbs around sessions and when your total carb needs increase.

When should I be consuming carbs?

The general rule of thumb would be to place more of your daily intake around your workouts. To sandwich them, one might say (pun intended). Carbohydrates consumed prior and during your session are more likely to be used for fuel during your run/ride/swim. While carbs consumed after a session are sucked up by our muscles at an increased rate to replenish any glycogen losses that occurred.

The importance of carb timing will also depend on other aspects of your diet and training. For example, if you’re consuming an adequate amount of calories (not trying to lose body fat), and follow a moderate/high carbohydrate diet, then the timing of your carbs gets washed out by the fact that you’ll rarely be in a glycogen depleted state. The only time this may be of more importance is if you’re training multiple times a day, in which case you should be slamming carbs between sessions.

On the other hand, if you’re in a calorie deficit you’ll likely need to be a bit more mindful of your carb intake. Placing those carbs around your training sessions is going to be of more importance if your priority is performance.

Practical Takeaway: Consume some carbs around your training sessions to maximise performance and recovery.

Training the gut…

This is probably the biggest issue that I see with new/intermediate endurance athletes. Not “training their guts” so to speak. No, I’m not talking about sit-ups or channelling my inner football coach calling you “soft” for not having “guts”. Just like the rest of the body, our digestive system is extremely adaptable. I bet you never thought of your gut as an important organ for performance. But think of it like this. Our performance is dependant on fuel and fuel delivery is dependent on… you guessed it. Gut function.

I can’t understate the importance of training your gut for the environment in which it’s likely to be during a race/event. Gastro-intestinal issues are extremely prevalent in during endurance events and often this is due to not spending the time training the gut. So how do we train our gut you ask?

Starting far from competition, we aim to replicate the nutritional conditions of the race/event. Leading researchers suggest getting comfortable consuming high amounts of carbohydrate, utilising simple carbs during your exercise sessions and finding carbs that don’t cause GI distress and make you feel good can all be effective in reducing the likelihood of gut problems on race day.

Key Takeaway: Don’t decide on the week of your event/race that you’re suddenly going to carb load, introduce new foods/drinks and consume gels. This is a recipe for disaster as the gut won’t be used to that amount and potentially type of carbohydrates. Practice your event day approach on long runs.

That’s it for part 1. Stay tuned for part 2 where we’ll dive into event specific fuelling and recovery.


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