How to fuel during your training sessions

Have you ever heard of intra workout nutrition? This is when people consume carbohydrates during their training or workout session and will be the topic of todays blog post.

Athletes who train most days of the week for periods of 1 hour or more run down their stores of muscle glycogen, even when they consume a diet high in carbohydrates. When muscle glycogen stores are running low, it can lead to the feelings of ‘heavy limbs’ and fatigue which can ultimately result in poor performance. Therefore, avoiding muscle glycogen stores running low through consuming carbohydrates during your session is definitely worth considering.

How does it work?

The body uses carbohydrates and fats as fuel. Fat is the main fuel for low intensity exercise or aerobic exercise, think of zones 1 and 2. However, carbs are the main fuel for more higher intensity exercises in zones 4 and 5. These have been previously covered by Aaron in the fuelling for training blogpost which you may want to revisit!

Ultimately, the body has more fat stores than carbohydrate stores. Even extremely lean athletes will have more fat stores and enough to fuel long moderate intensity exercise. The usual athlete will have relatively moderate amounts of carbohydrate stores as muscle glycogen and will also have stores available in the liver, if needed. However, these stores will run out during intense exercise, so this is when fuelling during training comes into play. This is because when these stores run out fatigue will set in. You may have experienced ‘hitting a wall’ in a race before and with fuelling during exercise our aim is eliminate this problem.

Fuelling during the race

The amounts of carbohydrates you will need is entirely individualised and will depend on:

1.  Physiological demands of the sport – duration and intensity
2.  Physiological profile of the person – height, body weight and body composition
3.  Training status – the more trained an athlete is the higher their ability is to use fat as a fuel source

If you are running a marathon or have a long-distance race, it is important to be familiar with the route and know what foods and drinks may be available to you and what you will have to bring yourself. Longer races will require more carbohydrates than shorter races or events. Events lasting 2 hours or more may require anywhere from 60 to 120 grams of carbohydrates during the event. This target can be achieved through combinations of sports drinks, gels and solid foods. The general rule of thumb is 30-30-30, where 30g comes from sports drinks, 30g comes from gels and 30g comes from solids. However, this will vary for each person depending on your event and it is extremely important to trial this before any competitive event as it may not suit everyone. This will help reduce the occurrence of any gut problems, such as cramping or bloating. We can help you come up with a specific nutrition plan during training based on your race, performance goals and individual preferences. This leads me nicely onto our next topic of carb manipulation.

Carbohydrate manipulation

This means altering your carb intake to fuel training and recovery and allows for the greatest training adaptations and benefits. Prior to an endurance event, which is greater than 90 minutes, carbohydrate loading is recommended in the 24 hours before the event. This will elevate the muscle glycogen stores and delay fatigue by about 20% in endurance events.

Currently, the recommendations for prolonged exercise lasting 2-3 hours are for athletes to have 60g of carbs per hour. For well-trained athletes competing for over 2.5 hours this increases to 90g per hour. Around 90 minutes into endurance events is the recommended time to consume some carbs, which can come from fluids, gels or energy bars. Evidence has shown that high carb intakes reduced 30km running events by 8 minutes, which is a huge win for our athletes in our eyes!

Another way to manipulate your carb intake is through carbohydrate mouth rinsing. This is most beneficial when you swirl a sports drink around your mouth for 5 to 10 seconds and then spit it out. Carb mouth rinsing involves activating receptors in your mouth and brain involved with reward, which subsequently improves performance. This has been found to be most effective when athletes glycogen stores are reduced or when you feel fatigued. While the exact way this works in the body is not yet fully understood by scientists, they have revealed that it improves both cycling and running performance through faster time trials for cycling and increased distance gained during time trial running events. This may be handy tip to experiment with during trainings if you are prone to GI upset during events as you wont actually be consuming any carbs, however, by swirling them round in your mouth tricks the brain into thinking you are going to eat something sweet.

Here's a table of the amount of carbs (CHO) recommended for different exercise durations (Jeukendrup, 2011).

*60 g.h^-1 means 60g carbs per hour

Should I pick sports drinks, gels or solid food though?

Sports drinks are designed for exercise lasting more than 90 minutes, to provide a convenient fuel and fluid delivery. They usually contain about 6-8% carbohydrates or 6-8g of carbs per litre. If sports drinks have a higher carb content than this, it can lead to gut upset during events and impair performance. If you are unsure on which brand to choose, use total carb contents between 3-4g per 500ml as a general guide when looking at the nutrition information label.  

In the case of gels, they provide ~20-25g of carbs per pouch and come in a wide variety of flavours. Some may even contain caffeine. The exact type of gel you should use will depend on your needs, the duration of the race or event and the amount of carbs you will consume from other sources. However, they can be very easy to carry on you during events which make them an extremely convenient fuelling option during training, but they can be expensive.

In terms of solid foods, these are usually the most readily available options for athletes. Foods that are commonly used include: ripe bananas, white bread with jam, jaffa cakes and dates. The aim for these foods is to deliver a quick supply of easily absorbable carbs or simple carbohydrates. Therefore, the food you choose to trial should be low in fibre, fat and protein. This is why, as sports nutritionists, we would recommend white bread over brown bread. The major downfalls with solid foods are, however, they require chewing, they may contain more than enough carbs than needed and they take longer to digest than liquids or gels therefore delays gastric emptying which leads to adverse GI symptoms. For these reasons, some athletes prefer to use sports drinks and gels in their intra-workout nutrition strategies.

A quick note on caffeine

Many of you may start your day with a caffeine kick, I know I do! However, with caffeine timing is crucial. This is because caffeine takes 30-90 minutes to be absorbed in the body. Studies have shown that athletes undertaking endurance events lasting 2-3 hours may benefit from taking in some form of caffeine during their sporting event. However, some athletes may be highly caffeine sensitive, where they may become nauseous or jittery after consuming caffeine, while caffeine may not affect other people at all. The key here is to find your own optimal intake. This can come from energy drinks, espresso’s, carbonated drinks or caffeine gels. The average caffeine contents of these are outlined below as a useful guide. It is recommended not to exceed 400 mg of caffeine per day.

Conclusion

In short, fuelling during your training session may be something you want to consider as an athlete if you:

1. Experience fatigue during endurance events
2. Want to improve your performance outcomes
3. Feel you could benefit from a boost of energy mid workout

But the key caveat here is that you MUST train your gut to get used to this approach. On easy training days, where you train low or use fat as an energy source, you may want to consume little to no carbohydrates. On high intensity training days, you want to train with plenty of glycogen stores to fuel for the work required and fuelling during training may fit nicely into your plan here!

Take home messages

1. Don’t experiment with new foods on race day
2. Train with the same nutrition products for at least 6 weeks prior to race day
3. An individualised approach is key
4. The benefits of caffeine are best consumed 30-90 minutes before training
5. During high intensity sessions, stick to sports drinks and gels rather than solid food options to avoid digestive problems
6. PRACTICE, PRACTICE, PRACTICE

I would just like to thank you for checking us out and having a look at our blog. And please do remember that we are here to help you in any way we can so don’t be shy and get in touch with any of your questions, Id be more than happy to help you.

Don’t forget to download our E-book on Carbohydrate periodisation, where I will take you through the key concepts of how to match your carb intake to your training intensity.

Grab our eBook

Here are the main areas that I cover in this eBook that can help you take control and push your performance to the next level.

1. How to fuel training sessions based on intensity (high/low)
2. 6 key ways to pull off training low 
3. 3 ways to optimise training high 
4. The 3 most important variables to take into account 

References

Burke, L., Hawley, J., Jeukendrup, A., Morton, J., Stellingwerff, T. and Maughan, R., 2018. Toward a Common Understanding of Diet–Exercise Strategies to Manipulate Fuel Availability for Training and Competition Preparation in Endurance Sport. International Journal of Sport Nutrition and Exercise Metabolism, 28(5), pp.451-463.

Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro, Seco-Calvo J, Urdampilleta A. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners. doi: 10.3390/nu12051367

Cermak NM, van Loon LJ. The use of carbohydrates during exercise as an ergogenic aid. Sports Med. 2013. doi: 10.1007/s40279-013-0079-0. PMID: 23846824.

de Ataide e Silva, Thays et al. Can carbohydrate mouth rinse improve performance during exercise? doi:10.3390/nu6010001