How to Fuel for your Sport

For the longest time, athletes prioritised training for their sport and fuelling was a secondary consideration. Yet, fuelling can give you the edge and we are seeing more athletes apply their training and fuelling strategies in unison. In fact, for such athletes, training is now considered complete only when refuelling is done.

There is “no one shoe fits all” formula when it comes to nutrition and our takeaway message is test, test, test! Test different fuel sources, at different intensities and durations of your exercise. Test in combination with other fuels, test when doing different activities, e.g., running, cycling, ball sports, etc. Testing helps you learn what fuel powers your sessions best, how much of that fuel you can handle and when. This can spell the difference between podium or PB, completing and DNF or winning and losing. It is highly likely you will need multiple sources of fuel too when doing a single sport. For example, you may find you consume different fuel sources on the bike leg compared to that of the run leg when doing a longer distance triathlon.

Carbohydrate Storage In the Body

Carbohydrate storage is somewhat limited in the body compared to fat. Carbohydrates are stored mainly in the form of glycogen in the muscles and liver. Blood glucose is comparatively small and ranges somewhere around a teaspoon or less. This level is tightly controlled by a host of physiological processes however, liver and muscle glycogen can vary widely across individuals and influenced by their nutrition, exercise type, intensity, and duration.

The liver drip feeds glucose into the bloodstream at a rate similar to the uptake of glucose by the working muscles from the blood. This is partly to ensure the brain, which is heavily dependent on glucose for normal functioning, gets a steady flow of glucose in addition to maintaining a harmonised blood glucose concentration of around 70 –100 mg/dL (4.0 and 5.5 mmol/L)

As liver glycogen levels fall, the liver can increase the metabolism of amino acids and glycerol to produce glucose. However, the rate of this production is limited and cannot keep pace with glucose removal from the blood during exercise. This is one key reason why a regular intake of carbohydrates is necessary.  

Carbohydrates start to break down in the mouth as soon as they are ingested. They are later passed and digested and absorbed in the stomach and soon pass to the liver and stored ready for action. 

Muscle glycogen and blood glucose are essential substrates for working muscles. Prolonged exercise can result in these being depleted and you left feeling fatigued i.e., “bonking”. You also risk depriving your brain of an essential fuel source, which can hinder judgement - be it making the right call in a rugby lineout, misjudging tennis serve or not paying attention and avoiding the drafting zone in a triathlon. Maintaining optimal muscle and liver glycogen and blood glucose levels can help deliver the performance you are after, while preventing fatigue and loss of concentration or poor judgment.

Studies on athletes and their performance in a pre-fuelled state have consistently shown those who start fuelled always outperform those that weren’t. Some reported a +15% improvement in performance towards the end of testing. Given a lot of races and games are won within the last few minutes or seconds, this can translate into winning or not.

Carbohydrate Oxidation

Most studies on fuelling have been done on endurance athletes. However, studies such as Foskette’s 2008 demonstrated the endurance capacity of intermittent sports improved with carbohydrate fuelling as did the time to exhaustion. There are several other studies similar to this highlighting the positive impact of fuelling in intermittent sports.

As carbohydrates can improve exercise performance across sports, there are simple guidelines we list below to help optimise your fuelling. The intensity and duration are a couple key determinants of any fuelling strategy. Working out at lower intensities results in lower levels of carbohydrate oxidations rates and likely lower levels of carbohydrate utilisation. Therefore, you should adjust your exogenous carbohydrate intake accordingly.

Your hydration and fuelling strategy should be aligned to your training program. Whilst you can mix your fuelling strategy up with drink mixes, gels, bars, blocks, etc, one should remember fluid absorption and digestion can be impacted by many factors such as the concentration of carbohydrates, calories and liquid in the gut, stress levels, heat, dehydration level and so on.

 

How To Take In More Carbohydrates

One strategy to optimise carbohydrates intake per hour is by consuming multiple transportable carbohydrates.

All that means is by combining glucose and fructose (fruit sugar) simultaneously, you can take in more carbohydrates per hour than simply taking glucose on its own. Although both sugars are digested the mechanics in which that happens are slightly different. Current research suggests a glucose to fructose ratio of 2:1 will optimise this process.

Here is the technical explanation for those interested. Glucose is transported through a sodium-dependent glucose transporter protein SGLT1. Once this transporter is saturated with glucose then further exogenous carbohydrate oxidation becomes limited. Fructose on the other hand is absorbed by a sodium-independent transporter GLUT5 . Saturating these two transporters can result in higher total exogenous carbohydrate delivery and absorption. In particular, studies repeatedly show maximum glucose oxidation rates of up to 60g per hour when consuming glucose only. Throw fructose into the mix and athletes have shown to a have total carbohydrate oxidation rates of 90g of per hour and some.

These are some of the key drivers behind us at ACTIVE VITA using multiple carbohydrates in our drink mixes. Another reason is digestion rates of different carbohydrates differ between athletes, so having multiple forms of carbohydrates in the proposed ratio allows the optimal absorption rates regardless of which carbohydrates your body prefers.

 

Fuelling Guidelines

You can categorise fuelling into before, during and after exercise. Although we give you the details below, it’s imperative you test what works for you. Use the below as guidelines rather than hard and fast rules to optimal fuelling and always rely on well-balanced eating plan with wholesome whole foods where possible.

Your goals during exercise lasting longer than 60 minutes should be 1. Prevent dehydration, 2. Optimise your fuelling, and 3. Maintain electrolytes. Your fluid intake should be based on your sweat rate. You should not be taking on more fluids than you sweat. At ACTIVE VITA we have an online sweat rate calculator you can use to determine your sweat rate and ideal fluid replacement levels for any sport. We also show you other ways you can determine your sweat rate.

Fuelling can come from drinks, gels, bars, blocks, food, etc. so long as the fuel is coming in at a digestible rate and keeps you going with no Gastrointestinal (GI) issues. The more liquid the fuel, the easier it will be to digest. However, be mindful on taking in too much liquid or using a liquid based-fuel as your only fuel source. For intense efforts in rugby, football, basketball, etc. you may want to avoid chewing and stick with drinks and gels, which are easier to get down. Remember when taking gels, they should always be chased with water regardless of the activity.

As mentioned above, lower exercise intensity results in lower carbohydrate oxidation rates so you will need to adjust your fuelling intake accordingly.

Consider the exercise intensity, duration, type of carbohydrate, the amount of carbohydrate, activity type, the activity rules and regulations and your own experience on what works for you when designing your hydration and fuelling strategies. 

Given that some of your performance depends on mental grit and focus, you may find it in your favour to keep fuel levels topped up, so that your brain has the nutrients it needs to maintain its focus and make good calls.

The tables below give you a detailed landscape on hydration and fuelling. 

Before Exercise  

During Exercise  

Practice Everything In Training 

Training is an ideal time for you to put your hydration and fuelling strategies to the test, increase the absorptive capacity of the intestine, reduce your chances of GI issues and see what you can tolerate and when. In some activities you may tolerate greater intakes than others. For example, you may find you can take on more fluids and fuel when cycling and prefer blocks when running.

If you are embarking on a hydration and fuelling strategy then always start off with small amounts and build up over time. Ideally you don’t want to be changing any hydration or fuelling strategies within the 10 weeks of your big race or game day.

If you are using our drink mix at ACTIVE VITA for example, you could add 1 scoop into your 500ml – 750ml bottle with water and see how you go. The next session add 1 ¼ scoops and so on. A few tell-tale signs you are at your limit of fluid and fuel intake can be a sloshy stomach, stomach cramps, feeling very heavy in the stomach, wanting to throw up, passing gas up and out from the gut and butt etc. It’s certainly unpleasant to experience any of these. If you do start to experience these feelings, then back off the intake and if need be slow the rate at which you are working out too. This will allow the body to focus more energy on digesting what is already in the system. Once you work through this and the stomach starts to settle then gradually turn on the burners and off you go. 

Hydrate and fuel only as much as you need to keep you going safely and optimally. You should never aim to replenish 100% of all fluids, carbohydrates, or electrolytes during your activity.

Remember, use wholesome whole foods where possible. For example, a semi skimmed glass of chocolate milk gives you a bunch of electrolytes and an optimal protein to carbohydrate ratio plus many other nutrients – a very effective post exercise option. A large glass of orange juice will replace just about all your electrolytes lost in most sports including a marathon. When food is not possible or preferable then look to sport nutrition alternatives.