Fuelling For An Endurance Event

Whether it’s your first marathon, an arduous day in the saddle climbing ‘Peaks’ or tackling another Ironman triathlon… nutrition is crucial when it comes to optimal performance.

All too often we see athletes dedicate so much time and energy into their training with little to no consideration given on how to fuel their event.

How far do you think you’ll get if there’s no fuel in your car? Our bodies are no different – we need to be fuelling with the right foods and amounts that will support your chosen event.

Before we discuss race day strategies, a little nutrition 101…

The body uses two main fuels: carbohydrate and fat. Fat is the primary fuel for less intense exercise (low to moderate intensity: often referred to as aerobic) while carbohydrates are the primary fuel for intense exercise, moderate to high intensity). Carbohydrate can deliver energy much faster to the muscles than fats. Thus, carbohydrates are the performance fuel, whilst fat is like “diesel” important for longer distances at slower pace.

The body has stores of both fuels, but unfortunately the stores for carbohydrate are much smaller than those of fat. Even the leanest athlete has sufficient fat to sustain the longest races at moderate intensity (thousands of grams of fat). The typical athlete will have approx. 500-800g of carbohydrates stored in muscle and liver glycogen (a small fraction versus fat stores); enough to fuel ~1-2hours of intense exercise.

Endurance athletes are familiar with “hitting the wall”; this is the point where carbohydrate stores become depleted - usually around the 32km point of a marathon. At this point, a runner has only fat for fuel and intense performance cannot be maintained (unless carbohydrates are consumed)

I will never forget my first (and last) marathon – let’s just say even dietitians can get it wrong on race day! Whilst I crossed the finish line in a respectable time, the last 10k’s was miserable and I can honestly put it down to my nutrition, or lack of!

So, for your next event, let’s have a nutrition plan in place with the following strategies to consider:

1.    Before you get to race day, focus first on your training nutrition and hydration

Fuelling and hydrating to get the most out of your training sessions is key to being race ready!

Nutritional preparation should not start the week or two before your event. It should start at least 6-10 weeks before your race and plays a crucial role through the entire preparation phase. Training will always involve a mix of hard and easy; same is true for nutrition. On easy days where quality of training is not so important and where you may purposely want to train your body to use fat as a fuel, you will consume little or no carbohydrate (“training low"). On other days that are hard, where quality is important and where you want to train your body to perform just like you will in a race, it is a good idea to follow your race plan. Training with your race day nutrition not only fuels your sessions but it’s also ‘training your gut’ – reducing the risk of gastrointestinal upset on race day.

TOP TIP: Don’t experiment with new products on race day - use the same nutrition products for at least 6 weeks prior to your event. A different gel, drink or bar has the potential to bring about GI discomfort including abdominal pain, bloating, vomiting &/or diaarhoea – let’s not risk it!

2.    Nutritional preference

What’s your go to? Keeping in mind carbohydrate is the body’s preferred fuel source, we are wanting fast acting carbs to be delivered to the working muscles. This can either be in the form of gels, chews, liquid or solid foods (bars/sandwiches).Experiment and find what works for you, remember: what works for one athlete may not necessarily work for you! Once you have your preferred fuel source figured out, you’ll also need to consider; carrying your nutrition on race day and the on-course nutrition available at your event.

3.    Nutrition and hydration during your event

Amounts & timing will vary from athlete to athlete, hence why it’s so important to have your own plan. The duration & intensity of your event will dictate the amount of fuel required. Longer events (>2hrs) & athletes should be aiming for ~60g carbohydrate/hour however some athletes may not require this much where others may need more (up to 90-120g/hr). Same for hydration, every individual has varying sweat rates and therefore replenishing fluids is based on individual requirements. In addition to replacing fluid loss, electrolyte loss also needs consideration. Making sure your fluids have adequate electrolytes is crucial, in order to avoid a condition known as hyponatremia (low sodium levels).

TOP TIP: A 2% decrease in body weight (dehydration) can have a negative impact on performance, therefore staying hydrated during your race is important – also prevent starting your race dehydrated, with adequate fluids pre-race. Also, listen to your gut - when fluids are not emptying from your stomach reduce the intensity temporarily. You will benefit from this later in the race!

4.    Nutrition before your event

The few days leading up to your event and the morning of, need consideration and planning as certain nutrients will impact on digestion and potential GI issues on race day.

Here we are aiming for maximal glycogen stores (stored carbohydrate). Think additional carbohydrates 1-2 days prior to your race (without overeating) and a substantial breakfast the morning of race day to replace liver glycogen stores used overnight. We are also aiming to limit the amount of fibre to reduce the risk of GI upset. Pre-race breakfast should be high in refined carbohydrates whilst low in fat and protein for optimal digestion.

TOP TIP: Plan your breakfast on race day well in advance and make sure it is available for you on race day. Don’t just show up for breakfast in a hotel on race day without checking.

These are just a few strategies to consider when devising a nutrition plan for your next event. I strongly advise seeking guidance and support from a Sports Dietitian who will help create a plan that is tailored to your specific requirements and goals