The Importance of Nutrition For Training

And so we turn to possibly the most controversial, devise of topics when it comes to marathon training: nutrition. Good sports nutrition isn’t all about eating endless salads, getting your 5(read 10!)-a-day, and eating plain chicken. It’s about eating appropriately for your training, taking on the right thing at the right time to support each training session, meaning you get the most from that perfectly planned program.

Unfortunately, nutrition is a hugely controversial topic these days, meaning deciding on the best nutritional strategy for your training has never been more complex. Whether it’s keto v veganism or low carb high fat v high carb low fat, the extreme approaches are matched only by the strength of belief that proponents of a given strategy have in their chosen dogma. In this post, we’ll take a look at why it’s important to get your nutrition right around your training and provide a few evidence-based tips along the way.


Why it’s important: your pre-training nutrition fuels the session you’re about to complete. The body can use either fat or carbohydrate during exercise, but the higher the intensity (for example during interval or tempo runs), the greater the reliance on carbohydrate. That’s because you can get energy from carbohydrate far faster, and for a lower oxygen cost compared to fat. The body can store carbohydrate in the muscle (~500 g) and liver (~100 g) as glycogen. Muscle glycogen provides an immediate supply of energy, while liver stores are used to maintain blood sugar levels. If you train first thing in the morning, your liver glycogen stores are likely to be almost entirely depleted, as they have been used to maintain blood sugar levels overnight without being topped up. The same applies if you train four or five hours after your last carbohydrate rich meal. Therefore it is likely your body will be a little low on the total amount of carbohydrate stored, and as such you have less available to use for high intensity training.

What to look for: the primary goal here is going to be topping up your liver glycogen and giving your body an energy boost before your session. Research suggests that ingesting ~60 g of carbohydrate ~60 min before exercise can provide exactly what you need. In real terms, that could be an energy bar, a couple of slices of toast, or a banana, or you might find it easier to take on fluid rather food before a session. Kenyan runners are famous for their incredibly sweet tea consumed just prior to running!

Top tip: consider whether you need the carbohydrate boost. Lower intensity sessions don’t have such a reliance on carbohydrate, and a growing body of research suggests that training in a carbohydrate depleted state can be beneficial at a cellular level.


Kipchoge nutrition
Why it’s important: the glycogen stores I mentioned above can see you through around 90 min of moderate-high intensity endurance running. After this time, you will run out carbohydrate and be forced to switch to predominantly burning fat. While this can be a useful training target, we can’t get energy from fat as quickly as from carbohydrate, meaning the pace at which you are running will drop. If you’re running a long tempo session deep into marathon training, it will therefore be worth topping up your limited supplies of carbohydrate mid-run to ensure the quality of those later intervals don’t drop off. On your longest of long runs, mid-run nutrition could also be the difference between completing the run, and being forced to get the bus home.

What to look for: research suggests the body can absorb between 60-90 g of carbohydrate every hour during exercise depending on the type of carbohydrate you ingest. It may not be necessary for you to max these out depending on your session, and in any case high carbohydrate intake during running could leave you dashing behind a bush mid-run. You can experiment with energy gels and drinks, or try gummy bears, Haribo or even raw jelly cubes work well!

Top tip: use longer runs to practice your nutrition for race day. We’ll discuss specific race day nutrition in a later blog, but plenty of research suggests that you can train yourself to take on more carbohydrate without stomach issues, resulting in faster race times. It also means you know exactly what to do come race day!

Post Run

Why it’s important: Traditionally, the goal of post-run nutrition has been to make sure you recover quickly and you’re ready to go for your next run as soon as possible. During a long or high intensity run, you will burn through your glycogen stores, and are likely to cause some muscle damage. As a result, guidelines have focussed on quickly restoring your carbohydrate stores, and taking on protein to help repair muscle damage.

More recently, research is starting to uncover the importance of the post-exercise window for maximising the physiological adaptations that are triggered during your run. Fitness is gained as the result of cellular adaptations, and ultimately the formation of new proteins within the cells such as mitochondria and glycolytic enzymes. As a result, the importance of ingesting protein in the post-exercise window to maximise the production of these new functional proteins has been amplified. However, contrary to previous guidelines, it’s also been shown that some of these cellular adaptations might be upregulated when carbohydrate stores are low. Therefore it could be important to deliberately restrict carbohydrate intake after training in certain situations.

A Roasted Chicken Dish

What to look for: if you’re going for the high carbohydrate option, consider between 1.2-1.5 g per kg bodyweight per hour for 3-5 hours after exercise, starting within 20 mins of the end of your run. The most up to date research suggests that if you can combine glucose and fructose then your subsequent performance in training will be better than if you take on glucose alone. Consider fruits, honey and syrups as sources of fructose, or make your own recovery drink by purhcasing the constituent ingredients and mixing yourself! Supplement this with ~20-30 g of protein at the end of exercise to help recover muscle damage, and possibly increase the total amount of carbohydrate you store. This could be taken as an immediate post exercise meal, bar or drink, and subsequent snacks such as bananas or oats. Elite runners of the Rift Valley are famous for their ugali- a type of corn flour porridge they eat by the ton! If you’re going for the low carbohydrate option, increase your protein intake slightly, and cut out carbohydrates in the hours after exercise.


Top tip: consider what your main goal for recovery is. Do you have a hard training session later that day (or first thing the next day if you’ve trained in the evening)? In this case you may want to prioritise getting ready for the upcoming session. Or do you have more time to recover, or only low intensity training planned later? In this case, you might be able to afford to remain low on carbohydrates and help your body maximise the adaptations it will make from your session.

Context is King

Hopefully these evidence based nutrition tips will be useful in your training going forward. The most important thing to remember is that nutrition sits within the context of your training, and your session for that day will dictate what you eat and when. I always find that if I can justify my nutritional choices in the context of training, I’m well on my way to supporting my training with proper nutrition. Why not try the same? A combined food and training diary can be a great way to get in the habit of thinking hollistically around the issue. Need a hand? Get in touch to arrange an initial consultation!