Nutrition and Hydration
Nutrition and Hydration
If you want to run further, stronger, and more consistently, you need to respect the three pillars of endurance fuelling: carbs, water, and electrolytes. Ignore any one of them and your legs will let you know.
1. Carbohydrates: your primary fuel 🏃♂️
Carbs are gas in the tank. When you run, your body relies heavily on glycogen (stored carbs) to power each stride.
- Carbs fuel workouts, long runs, and races
- Low carbs = heavy legs, early fatigue, and that “I’ve hit a wall” feeling
- Adequate carbs help you maintain pace, form, and focus
If you’re running longer than ~90 minutes, you should be taking carbs during the run—not just before and after. Most runners use gels as their main carb source, but you may find you prefer more natural products.
2. Water: performance depends on hydration 💧
Water keeps everything moving—blood flow, temperature regulation, and muscle contractions.
- Even mild dehydration increases perceived effort
- Dehydration raises heart rate at the same pace
- Poor hydration slows recovery and increases injury risk
Don’t wait until you’re thirsty on long or hard runs. Sip early, sip often.
3. Electrolytes: the silent performance protectors ⚡
Electrolytes (especially sodium) help your body absorb water and keep muscles firing smoothly.
- They prevent cramping and muscle misfires
- They replace what you lose through sweat
- Plain water alone can dilute electrolytes and cause problems on long runs
If you’re sweating, running long, or training in heat/humidity, electrolytes aren’t optional—they’re essential.
The Big Picture
- Carbs fuel the engine.
- Water keeps the engine cool.
- Electrolytes keep the wiring intact.
When all three are dialled in, running feels controlled instead of chaotic, and strong finishes become repeatable—not lucky.
Train your fuelling the same way you train your legs. Training runs are the perfect opportunity to experiment and find out what works best for you.
One More Mile only happens when your body has what it needs to earn it. 💪
Calculating your Nutrition and Hydration Needs
The levels of carbs, water and electrolytes required will vary from individual to individual, with external factors such as the air tempeature also playing a part. It's important to understand what your personal needs are.
Below are 2 methods for determing this, one is a quick option that will take you 5 minutes, the other is a more advanced approach.
Nutrition and Hydration
Nutrition and Hydration
If you want to run further, stronger, and more consistently, you need to respect the three pillars of endurance fuelling: carbs, water, and electrolytes. Ignore any one of them and your legs will let you know.
If you want to run further, stronger, and more consistently, you need to respect the three pillars of endurance fuelling: carbs, water, and electrolytes. Ignore any one of them and your legs will let you know.
1. Carbohydrates: your primary fuel 🏃♂️
Carbs are gas in the tank. When you run, your body relies heavily on glycogen (stored carbs) to power each stride.
- Carbs fuel workouts, long runs, and races
- Low carbs = heavy legs, early fatigue, and that “I’ve hit a wall” feeling
- Adequate carbs help you maintain pace, form, and focus
If you’re running longer than ~90 minutes, you should be taking carbs during the run—not just before and after. Most runners use gels as their main carb source, but you may find you prefer more natural products.
2. Water: performance depends on hydration 💧
Water keeps everything moving—blood flow, temperature regulation, and muscle contractions.
- Even mild dehydration increases perceived effort
- Dehydration raises heart rate at the same pace
- Poor hydration slows recovery and increases injury risk
Don’t wait until you’re thirsty on long or hard runs. Sip early, sip often.
3. Electrolytes: the silent performance protectors ⚡
Electrolytes (especially sodium) help your body absorb water and keep muscles firing smoothly.
- They prevent cramping and muscle misfires
- They replace what you lose through sweat
- Plain water alone can dilute electrolytes and cause problems on long runs
If you’re sweating, running long, or training in heat/humidity, electrolytes aren’t optional—they’re essential.
The Big Picture
- Carbs fuel the engine.
- Water keeps the engine cool.
- Electrolytes keep the wiring intact.
When all three are dialled in, running feels controlled instead of chaotic, and strong finishes become repeatable—not lucky.
Train your fuelling the same way you train your legs. Training runs are the perfect opportunity to experiment and find out what works best for you.
One More Mile only happens when your body has what it needs to earn it. 💪
Calculating your Nutrition and Hydration Needs
The levels of carbs, water and electrolytes required will vary from individual to individual, with external factors such as the air tempeature also playing a part. It's important to understand what your personal needs are.
Below are 2 methods for determing this, one is a quick option that will take you 5 minutes, the other is a more advanced approach.
Use this short questionnaire to provide you with a fuel and hydration plan.
You will receive a report similar to this.
The questionnaire is provided by Precision Fuel and Hydration, I'm a big fan of them. They have taken a very scientific approach to endurance runners' needs and offer a range of products that are highly respected in the running world. I should add that this is just a personal view, I have no direct connection with them. Other brands are available too!
1. Carbs
Use this chart to determine your likely level of carb replacement needed during an endurance run. For most marathoners, this will be in the region of 60g per hour, but use your long training runs as a way of finding your own sweet spot for carbs.
And a key factor to remember is that you should be fully carbed up beforehand.
2. Water
Use the sweat rate calculator to determine how much water you need to replace each hour during your long runs. Before the run you simply need to weigh yourself and any liquid you will be taking on the run. Then do the same as soon as you get back from the run, and update columns A-F in the spreadsheet. Your water loss through sweat per hour will then appear in column J.
Create a new entry for every run you record in the form, as sweat loss will vary based on temperature and intensity of the session. Come race day, you can reference the most relevant entry to determine your hydration strategy.
This form can also optionally be used for calculating your sodium loss but this is dependent on you having an advanced sweat test (see below).
3. Electrolytes
Being a heavy sweater doesn't necessarily equate to high sodium loss. Some poeple sewat a lot but their sweat has a low sodium content. Others who sweat very little may have a high sodium content.
For the ultimate precision assessment of your sodium loss, book yourself in for a sweat test assessment. Search online to find somewhere local to you (or ask me for advice on this). As an example, I've used The Edge in Leatherhead before.