Fuelling for Optimal Performance.

Focus on endurance sports & athletes (inclusive of beginners, recreational and elites)

Introduction 

Eating to support movement and basic human functions is necessary for everyone, despite your fitness or activity levels. Why? Our body needs fuel to produce adenosine triphosphate (ATP) - the body’s energy system.

In a more simplified explanation, food contains three main macronutrients: fats, carbohydrates, and protein, which all have their particular function and purpose in the human body. The body utilizes all three macronutrients for the production of ATP, however the primary energy producing pathway is from a reaction called glycolysis. Basically, this converts glucose molecules broken down from food and undergoes a series of chemical reactions to create energy to be used. Any food that does not require utilization will be stored in different forms and compartments of the body such as fat.

In this article, the key nutrition tips to fuelling your body optimally in endurance based sports will be broken into three stages:

  1. Pre-Training Fuelling

  2. Intra-Training Fuelling

  3. Post Training Fuelling 

*Hydration will be touched lightly in each step. 


By Lizzie Gralton

Finding Your Balance Dietetics

Febuary 2025

Pre-Training Fuelling

What is the Role of Pre-Training Nutrition?

  1. Ensures adequate energy for session to feel good and get most Improvements in strength and endurance.

  2. delays onset of fatigue during exercise.

  3. Enhances focus and cognition. The brain requires carbohydrates to maintain mental clarity and alertness, essential for executing technical skills and particularly when making decisions in team sport. 

  4. Supports muscle repair and growth by enhancing muscle protein synthesis and adaptation.

  5. Reduces delayed muscles soreness.

Who Needs to Consider their Pre-Training Nutrition?

If you are training in the morning for >45 minutes, or shorter duration but at high intensity, it is recommended to consume some carbohydrates 15-40 minutes prior for optimal performance outcomes and training adaptations. The amount of carbs and timing of ingestion does depend on time of day of your session.

If your goals are not performance focused but rather just participating in daily exercise for fitness and wellbeing, then it may be ok to train fasted as long as you refuel after training. But again this is very context and individual dependent.

What Food Should You Eat Before?

It is important to allocate at least 15 - 30 minutes before an early morning workout to consume some source of easily digested carbohydrate. This often would be something:

a) High in carbohydrates (20-40 grams or 0.5-1g/kg body weight)

B) Low in fats

c) Low in fibre

d) low-moderate protein

The reason behind this is to reduce any gut Discomfort or Disruption of carbohydrate transport to the working muscles during training. See examples on the cheat sheet provided in your newsletter.


Timing & Amounts

It is important to plan out the timing & types of carbohydrates consumed prior to exercise to avoid gastrointestinal discomfort as well as ensure maximal energy availability for performance. This can be difficult to understand at first but I have broken it down below for you. If you still struggle I recommend reaching out to more for a consult and plan to make it much easier for you.

Firstly, the timing and amounts depends on time of day.

For the early risers, it is important to prioritize your sleep so waking up 4 hours prior to your training is unlikely. In comparison, if you have a later afternoon training, you can start preparing your pre-training nutrition up to 3 hours prior. Below is the breakdown of how to optimize the timing & amounts of carbs leading up to training:

*however, it is important to note that you do not need to consume something each hour prior, instead have 1 meal 1-3 hours out and a top up snack 15 minutes before is gold standard. 

2-3 hours prior:

This is the ideal timing to optimize your muscle glycogen stores before your training / event. Ideally you want to aim for 2-4 grams of carbohydrate per kg body weight. This meal should also be low fibre and fats and some protein, around 0.4-0.6 grams of protein per kg body weight. An example of this meal could be something like a bowl of rice with a tin of tuna seasoned with and soy sauce or for the morning could be a glass of juice, 2 slices of raisin toast with jam and a Squeezy yogurt. 

1-2 hours prior:

At this point it would be a lighter meal, with almost only carbohydrate focused. For example would be something like a bowl of rice bubbles with milk and honey or maybe 2 crumpets with honey. 

<30 minutes before:

This is a great opportunity to top up your energy stores. Usually aiming for 0.5-1 gram per kg body weight or 20-40 grams depending on gut tolerance. An example could be as simple as a sports gel, or even just a couple pieces of dried fruit. 

Now lets talk about stage 2

Intra-training nutrition.

Why bother?

  1. Maintain blood glucose levels 

  2. Fuel your muscles and delay onset of fatigue / “hitting the wall”

  3. Get the most out of your training session by sustaining intensity for longer. 

  4. Train the gut to tolerate volumes and amounts of carbohydrates for race day.

Impact on performance if under or over-Fuelling during:

  1. Earlier onset of fatigue / higher risk of “hitting the wall”

  2. Reduced speed and power

  3. Increased risk of injury

  4. Reduce capacity to sustain exercise for long period of time

  5. Poor concentration and decision making.

  6. Technique errors and poor execution.

  7. Gut upset / excessive bathroom visits or incontinence.

  8. Poorer recovery / return to activity after race day.

Who should consider intra-training nutrition (not always necessary):

  • <45 minutes duration - Not applicable

  • 45-75 minutes high intensity or endurance training: small amounts of carbs such as sips of sports drinks / couple lollies / carb mouth rinses.

  • 1-2 hours of endurance session: 30-60g/hour of carbs.

  • 2-4 hours of endurance session: 40-60g/hour of carbs (needs to be mixed between fructose + glucose forms).

  • >4 hours of endurance Session / multi day: 90-110g/hour of carbs (multi-transport - mix of fructose and glucose).

What about gut tolerance & training the gut?

Athletes, particularly endurance athletes, commonly experience gastrointestinal (GI) discomfort due to many reasons, either mechanical, ischemic, or nutritional factors. For the purpose of this article we will focus primarily on the nutritional factors. But if you are interested in this topic I encourage you to have a read at this article.

Symptoms of Poor Gut Tolerance During Training:

  • Bloating 

  • Reflux

  • Abdo pain & discomfort 

  • Urgency / incontinence with bowel motions 

  • Fatigue

  • Dehydration

Common Reasons for these symptoms:

  1. Pre-training food (day before or even 30 minutes prior) - if too high in fiber, fats or protein.

  2. Dehydration or over-hydration.

  3. Nerves / Stress response.

  4. Too much carbs ingested during for body to absorb (malabsorption).

  5. High FODMAP ingredients in the gels / sports chews.

  6. Too much caffeine.

Ways to Improve Gut Tolerance during Exercise

  1. Start small, and increase the amount of carbohydrates ingested slowly during training. 

  2. Consider multiple carbohydrate transporters if consuming >60 grams per hour of carbs (co-ingestion of glucose + fructose) because glucose has a limited absorption rate. 

  3. Try different branded gels / liquids with different glucose / fructose concentrations. 

  4. Ensure low fats, fiber, and protein 1-3 hours before sessions. 

  5. Ensure hydrated prior to exercise and adequate fluid intake during. 

  6. Consider Low FODMAP diet leading up to long sessions or events. 

Summary:

In summary, food is fuel for your muscles and brain during your training. It is essential that we prioritize our nutrition during training just as we would like to do it for race day. We never want to go to race day feeling under prepared or not practicing our plan so the same rule applies for nutrition. If you need assistance with your fuel for training I suggest booking a 1:1 consultation so we can chat more and get you all set up.