Nutrition clinic: Fuelling on the move

Practice race day nutrition and achieve your goals.


by Dr James Morton

Welcome to our nutrition blog by Dr James Morton, Senior Sports Nutritionist for Science in Sport (SiS), where he will be giving advice on nutrition, dispelling fuelling myths and offering his tips every month. If you have a sports nutrition question or area you'd like to see covered in the blog, email editor@runnersworld.co.uk.

Fuelling on the move can be a constant source of stress for many endurance athletes, especially runners, where the practicality of fuelling is more complicated than whilst riding a bike. Unfortunately, there are no simple shortcuts to learning this skill other than basic practice. However, there are many competitive events (e.g. 5-10 km) and training runs where you may not even have to worry about drinks or gels - providing you arrive on the start line ready to go.

If your event or training session is less than 60 minutes long and the ambient temperature is moderate, then it is highly likely that consuming the relevant carbohydrate (CHO) and fluids with your pre-race or training meal will be sufficient to maintain your performance. In this situation, you should aim for around 2-3 g per kg body mass of carbohydrate (a 70 kg athlete should therefore aim for 140-210g) as well as consuming at least 500 ml of an electrolyte containing drink at 2.5-3 hours before you run.

You may consume a further 250 ml of fluid at 1.5 hours before the run with the aim that when you begin the race or training session, your urine output has normalised and is of clear or pale colour. In this way, you will have more than enough energy and hydration to perform adequately especially if you have also filled your glycogen stores the day before. If your training run is track based such as an interval type session, then of course you could also leave your electrolyte drink at the side and consume when required.

However, for those situations when we are exercising for longer than 60 minutes, you should pay more attention to the in-race strategy. First of all, you should practice this during training runs using a race belts. For optimal performance on race day, you should aim for 60g of carbohydrate per hour and hence should schedule at least one run per week where the in-race fuelling strategy can be practiced. In this way, you can practice the physical process of tearing the gel as well as training your stomach to digest this amount of carbohydrate.

In the beginning, it is likely you will have to slow down your pace for approximately 30 seconds or so until you develop this skill. However, with practice you will soon be able maintain a reasonable pace whilst consuming carbohydrate in gel format. Failing to practice the art of consuming gels whilst also not developing your stomach’s capacity to digest this amount of carbohydrate will only lead to gastro-intestinal problems and reduced performance on race day.

In relation to fluids, you must take advantage of the regular fluid stations on course with the aim to consume at least 500ml per hour, usually in the format of 150-200ml every 20 minutes or so. Try to avoid using products that you haven’t used before. Where needed, your thirst will usually dictate that you require more. Weighing yourself before and after every training run will allow you to increase your understanding of your sweat rate so you can practicing drinking enough to prevent excessive dehydration, typically in the magnitude of >2-3% body mass loss.

In summary, the golden rule of in-race fuelling is to practice and pay as much attention to this as you do your actual training times. Keep a diary and record: how you felt, how much you consumed, what happened to your performance, what flavours you liked, your body mass loss, your urine output and so on. This information is just as crucial as your training heart rates and minutes per mile pace. It could be the difference in achieving that PB on your next big event.

Dr James Morton is the Senior Sports Nutritionist for Science in Sport (SiS), the leaders in endurance nutrition. He has led and collaborated in over 40 research papers and publications and is also Senior Lecturer in Exercise Metabolism & Nutrition at Liverpool John Moores University (LJMU).


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I run the Khon Kaen marathon every January. The rules specifically restrict runners to what is provided by the organisers. This is water and a low carbohydrate electrolytic beverage 'Sponsor.

No gels,energy drinks or bars.

I wrote to the organisers and the IAAF asking if they thought this was good practice and got the usual everything we do is perfect, who do you think you are anyway, type reply not addressing the specific issues I raised. I take around the four hours and have never used gels anyway but I would be interested if you would be concerned about slower runners who would still be on the course when temp and humidity were begining to rise. www.oldmarathonrunner.co.uk 


Posted: 20/08/2013 at 15:55

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