Fuelling, Hydration & Caffeine For Runners

Hi team, Coach Alexa here. Wendy had a great question after her amazing and super challenging trail race over the weekend (which included hills, mountains, bogs, and all sorts!) Her question was around fuelling and hydration, focusing on a broader perspective, including hydration, energy, caffeine, where to pitch it, and how to get that balance right.

Personalised Approach to Hydration and Fuelling

The first thing to note is that hydration and fuelling are highly personal matters. While there are generic recommendations from science and research, the implementation of these strategies varies hugely from person to person. I’m going to talk through some of those general recommendations, and then how we might work out how that applies to us, with a few examples to support that.

Key Recommendations from Science

So let’s talk about fuelling to start with; taking on energy pre-run and particularly during a run, we’re looking for carbohydrates predominantly. The science gives us three useful facts. The first is that, on average, when your run duration exceeds 75 minutes, that’s when we need to start thinking about taking on during run fuelling.

Food packaging does include nutritional information, and will tell you the number of grams of carbs (and of that, the grams of sugars), so that’s a useful thing to look at when planning your fuelling. The science suggests that, on average, runners can take in between 25 and 60 grams of carbohydrates per hour. However, this range can be influenced by individual physiology and metabolism, and also changes with training.

The Role of Digestion and Energy Usage

Developing an understanding your own digestive system’s ability to process carbohydrates and deliver energy to muscle cells can be really helpful when experimenting with fuelling. Factors like physical size and the rate of metabolism play significant roles here. For example, a tall rugby player’s energy requirements will differ significantly from those of a lean endurance athlete.

Experimenting with Fuelling Strategies

To find what works for you, it can be really helpful to keep a diary around your longer training runs. Record what and how much you eat before and during runs, your energy levels, how your stomach feels, and any bowel issues. You could also monitor your heart rate and pace with a smartwatch or similar; if you notice your heart rate creeping up and your pace dropping, that’s often a sign that your hydration or fuelling wasn’t enough to support the run. That diary  iterative learning helps tailor a fuelling strategy that suits your body and running needs.

Fuelling Your Run: Start Early

Another thing to bear in mind is that it takes around 30 minutes for what we eat to become available as fuel, and that’s for the simpler carbohydrates (sugars) which are most quickly digested. So starting early with your fuelling, aiming for little and often, is typically easier on our digestive system and gives us a more consistent release of energy.

Fuelling, Ageing & The Menopause

Alongside the individual differences, there is some useful science specifically relating to women as we get older and head towards and through the menopause. There is some evidence that our bodies get less happy with digesting fructose (or “fruit sugar”) and that we tend to get less insulin sensitive (meaning we don’t react to that sugar in the bloodstream quite as quickly). What this means is that as you get older, what worked for you before from a fuelling perspective might well change and need some adaptations.

Running Hydration: Drinking to Thirst

A quick rule of thumb for hydration is to drink to thirst; if you’re thirsty, you need to drink something, and if you’re not you probably don’t. Assessing your hydration levels can be done by checking the colour of your wee post-run; aim for a light straw yellow colour which indicates good levels of hydration (darker urine typically indicates you should be drinking more). Again, this is a personal process of iterative learning that depends on individual’s body characteristics, as well as environmental conditions like weather.

Caffeine Consumption and Its Effects

At the risk of sounding like a broken record, caffeine intake and one’s response to caffeine varies greatly among individuals. I was coaching a runner a few years ago who was getting really awful headaches about two hours into her long runs. After a little bit of head scratching, we realised that it was likely due to caffeine withdrawal, as she’d normally drink ten to twelve cups of coffee a day, and so her long run was causing an extended gap between her usual coffee consumption!

It’s important to match your usual caffeine consumption during runs to avoid withdrawal symptoms. Caffeine, a performance enhancer, also has a stimulating effect on the digestive system, potentially affecting bowel movements (potentially increasing the chances of needing a poo on your run), urination frequency, and even heart rate too.

Concluding Thoughts on Runner’s Nutrition and Hydration

While I can’t provide explicit advice for every individual scenario without ongoing collaboration, these tips and insights should hopefully serve as a starting point for experimenting and understanding your body’s needs during running. Pay attention to the amounts and timing of your water, caffeine, and fuel intake, and observe how it affects your energy levels, digestion, and heart rate. With this iterative approach, you can build a personalised plan that works for you. Happy Running!