Your ESN Half Marathon Fuelling Guide

The half-marathon is a long, physically demanding challenge. To hit your goals at the ASICS Manchester Half this October, your training needs to be backed up by a solid eating and drinking plan. What you eat and drink is often the single biggest thing participants get wrong, which can slow you down in training and on event day.  

As the official nutrition partner for the race, ESN has created a simple, straightforward plan to keep your energy levels high, keep you hydrated, and help your body recover quickly. This guide breaks down exactly what to do during your main training runs and on event day. 

The ESN Energy & Recovery Products 

To follow this guide, you will use a few key products from ESN’s endurance line: 

ESN Perfect NRGY Hydro Energy Gel

A light, liquid-style energy gel that gives you a quick boost during long endurance sessions. Each gel delivers 20g of fast-acting carbs from a dual-carb blend, plus sodium, sea salt and coconut water powder to help support hydration. It’s fructose-free, plant-based and easy to digest, with a watery texture that’s easy to take on the go.

ESN HydroLoad Electrolytes

A drink powder designed to help you stay hydrated and keep your energy up before, during or after your run. It combines 5 key electrolytes to help replace what you lose through sweat, plus 18g of carbs for added energy. Its hypotonic formula is made to be absorbed quickly by the body, making it ideal for longer or more intense training sessions.

ESN GOAT Bar

A soft, oat-based protein flapjack made with real ingredients like egg whites, oats, nuts and fruit. Each bar gives you 14g of high-quality protein to support your muscles, plus 21g of carbs, fibre and healthy fats for balanced, longer-lasting energy.

 

Part 1: Fuelling Your Training Sessions

1. Easy Runs (Building Your Stamina)

  • What it is: A run of about 8 to 11 kilometres completed at a slow, comfortable pace where you can easily chat with a friend. You will usually do these twice a week.  
  • Before the event: Eat a normal meal that gives you slow-release energy (like brown rice, oats, or sweet potato) along with some protein about 2.5 to 3 hours before you start.  
  • During the run: Because these runs are shorter (around 1 hour) and less intense, you do not need to eat any extra food while running. Instead, just focus on drinking 500–600ml of water mixed with 1 serving of ESN HydroLoad Electrolytes to replace the fluids and salts you lose through sweat.  
  • After the run: Within 30 minutes of finishing, consume your ESN GOAT Bar to kick start your recovery (or eat a carb-rich meal) and help your muscles repair and restock your energy.

2. Progression Runs (Teaching Your Body to Push When Tired)

  • What it is: A run of about 9 to 11 kilometres total. You start off at an easy pace, speed up to your half-marathon pace in the middle, and finish fast. This teaches you how to keep running hard when your legs feel tired later in the race.  
  • Before the run: Eat a light meal with easy-to-digest carbohydrates (like white rice or white toast) and some protein 3 hours before you start.  
  • During the run: Aim to take in 30–60g of carbohydrates per hour. Take 1 ESN Perfect NRGY Hydro Gel at the 20-minute mark and a second gel at the 40-minute mark, washing them down with a few sips of water.  
  • After the run: Drink 1 serving of ESN Hydroload Electrolytes with an ESN GOAT to stop muscle breakdown and instantly start the recovery process.

3. Speed Sessions (Interval Training)

  • What it is: Short, fast bursts of running (lasting 2 to 8 minutes) followed by walking or slow jogging breaks to catch your breath. These sessions make you faster and improve your running strength.  
  • Before the run: Because you run very fast, your body relies heavily on carbohydrates for quick fuel. Eat a light carbohydrate meal 3 hours before. If preferred, consume caffeine 15–30 minutes before you start to help you focus and handle the tough effort.  
  • During the run: High-intensity running burns energy very fast. Aim for 60g of carbohydrates per hour. Take 1 ESN Perfect NRGY Hydro Gel every 20 minutes (at 0, 20, and 40 minutes) to hit this target exactly.  
  • After the run: Drink a refreshing serving of ESN HydroLoad Electrolytes and ESN GOAT Bar immediately to rebuild your muscles, replace fluids and restock your energy tanks.

4. Long Runs (EventDay Rehearsal)

  • What it is: Longer runs between 13 and 23 kilometres to build your basic endurance. Use these runs to practice everything you will do on event day, including the clothes and shoes you will wear, your breakfast, and your running snacks.  
  • The day before: Start loading up on energy. Eat plenty of carbohydrates throughout the day. Eat ESN GOAT Bars as snacks and sip water mixed with ESN HydroLoad between your main meals.  
  • Before the run: 3 hours before, eat a light breakfast of easy-to-digest carbohydrates (like white toast with jam or cereal) and some protein. Your body’s energy levels drop by about half while you sleep, so this breakfast tops your tanks back up. Include an ESN GOAT Bar or fruit juice for a quick energy boost.  
  • During the run: 
    • If the run takes less than 2 hours: Take 3 ESN Perfect NRGY Hydro Gels spaced 20 minutes apart to get steady energy.  
    • If the run takes longer than 2 hours: You need more fuel. Aim for 60–90g of carbohydrates per hour by combining your gels with bottles of water containing ESN HydroLoad Electrolytes.  
  • After the run: Drink a large serving of ESN HydroLoad Electrolytes and an ESN GOAR Bar within 30 minutes to jumpstart your recovery.  

 

Part 2: Quick Summary Table

 

Part 3: Event Day Blueprint | ASICS Manchester Half (October)

The Science Made Simple 

For most runners, a half-marathon takes between 1.5 and 2 hours to complete. When running at this speed, your body relies almost entirely on carbohydrates for fuel. If you do not eat enough carbohydrates the day before the event, your body’s energy tank will run out too quickly, causing you to slow down drastically and feel completely exhausted. However, if you carbohydrate load correctly in the day before the event, you will improve your ability to maintain your target pace and improve your overall performance.

1. 24 Hours Before the Event: Filling your Fuel Tank 

Eat plenty of carbohydrates today. Focus on foods that are low in fiber (like white rice, white pasta, white bread, and juices) so your stomach stays light and you do not feel bloated or get an upset stomach on the course.  

Example 24-Hour Plan for a Runner: 

  • Breakfast: A bowl of puffed rice cereal with milk, 1 banana, and a glass of fruit juice mixed. 
  • Mid-Morning Snack: 1 ESN GOAT Bar and a glass of orange juice. 
  • Lunch: A large white baguette with spinach, a little mozzarella cheese, and low-fat ham, plus a glass of water with ESN HydroLoad Electrolytes. 
  • Mid-Afternoon Snack: A bowl of rice pudding with a spoonful of honey and a glass of fruit juice. 
  • Dinner: A large portion of boiled white rice, a piece of grilled salmon, and a side of beetroot, plus a glass of water. 

2. Event Morning Timeline 

  • 3 Hours Before the Start: Eat a simple, familiar breakfast that you practiced in training (like white toast with jam or porridge) along with a little bit of protein. Sip on 500ml of water mixed with 1 serving of ESN HydroLoad Electrolytes up until 1 hour before the start to make sure you are hydrated.  
  • 30 Minutes Before the Start: Caffeine, in your preferred form, with a few sips of water while you wait in your starting area to help you feel alert and ready to go.

3. How to Fuel During the Event

Because ESN Perfect NRGY Hydro Gels are very liquid-like and smooth, they are easy to swallow without needing to wait for a water station. 

  • 0 to 20 Mins: Settle into your comfortable running rhythm. 
  • 20 Mins: Take 1 ESN Perfect NRGY Hydro Gel (20g of energy).  
  • 40 Mins: Take 1 ESN Perfect NRGY Hydro Gel (20g of energy).  
  • 60 Mins: Take 1 ESN Perfect NRGY Hydro Gel (20g of energy).  
  • 80 Mins: Take 1 ESN Perfect NRGY Hydro Gel (20g of energy).  

Keep taking a gel every 20 minutes until you approach the finish line. 

4. After the Finish Line

As soon as you cross the line, collect your medal, water and grab your ESN GOAT Bar. Consuming your ESN GOAT Bar within 30 minutes of finishing the event will immediately kick start your bodies recovery and starts rebuilding your energy so you aren’t as sore the next day.

 

Head to the ESN website and use your exclusive code ‘RUNMCR26’ at checkout to get 25% off all ESN products and start honing your ASICS Manchester Half fuelling strategy before event day.