Training for a half marathon is not only about the miles you put in each week. Fuelling is part of your training too, and it needs practising in the same way your long runs do.
Whether this is your first half marathon or you are trying to improve on a race that did not go to plan, working on your fuelling during your longer runs tells you what your body will tolerate. It also means race day is not the first time you try something.
Here is where to start.
Lucy, who I helped train for the Windsor Triathlon.
When should you start fuelling during a run?
On shorter runs you generally do not need to take any carbohydrate.
Once your training runs start lasting around 60 to 75 minutes or longer, it is worth practising the strategy you plan to use on race day.
Do not wait until you feel tired. Aim to take your first carbohydrate around 25 to 30 minutes into the run, and then keep taking it at regular intervals after that.
Work in time rather than distance. Five kilometres might take one runner 20 minutes and another runner 40 minutes, and what your body needs is tied to how long you are running for, not how far you have gone.
How much carbohydrate do you need for a half marathon?
Current sports nutrition guidelines recommend around 30 to 60g of carbohydrate per hour during endurance exercise lasting roughly one to two and a half hours.
You do not need to start at 60g an hour on your first long run. Begin at the lower end of that range and use your training runs to build up gradually to what you tolerate.
A simple starting structure could look like this:
- 30 minutes: first gel or chews
- 60 minutes: second gel or chews
- 90 minutes: third gel or chews
- 120 minutes: fourth gel or chews, if you need it
That is an example, not a prescription. Always check the carbohydrate content of the product you have chosen, because the amount in individual gels, chews and drinks varies considerably.
The carbohydrate you take each hour matters more than the number of gels you get through.
What should you eat during a half marathon?
There is no single product that suits every runner. Your options include:
- Energy gels
- Carbohydrate chews
- Sports drinks
- Dates
- Other easily digested carbohydrate sources
The best option is the one that gives you enough carbohydrate, is practical to carry and, importantly, sits well with your stomach while you are running. That last point rules out more products than runners expect, which is exactly why you test it in training.
STYRKR
STYRKR is one of the brands I use and recommend for endurance fuelling. They do a range of carbohydrate products, including chews, which can be useful if you prefer something more solid or you want an alternative to traditional gels.
Affiliate disclosure: the STYRKR link above is an affiliate link and includes a discount. If you buy through this link, Runfix may receive a commission.
What about hydration?
Hydration needs vary considerably between runners, and they change with temperature, humidity, how long you are out for and your own sweat rate.
As a general approach, take small, regular sips of water on longer runs and adjust what you drink according to the conditions and to how you feel.
If taking carbohydrate and a larger amount of fluid together upsets your stomach, try spacing your water away from your gels or chews. Take the carbohydrate, then have your water slightly later in the run.
Some gels are designed to be taken with water, so always check the instructions for the product you are using.
Again, this is something to practise in training rather than to try for the first time in a race.
Train your fuelling as well as your running
Your long runs are the place to test your whole race day plan. Use them to work out:
- What you are going to take
- How much carbohydrate you are getting each hour
- When you are going to take it
- How much fluid you need
- How your stomach responds
If something does not work, change it. You may need to adjust the product, the amount, the concentration or the timing before you find what suits you.
What should you do on race day?
One of the simplest rules for race day is this:
Do not introduce anything new.
Your half marathon should not be the first time you try a new gel, a new breakfast or a new hydration plan.
Use the products and the timings you have already practised. Eat a familiar pre-race meal, start the race properly fuelled, and take your first carbohydrate before you feel significantly tired or hungry.
For most runners that means starting around 25 to 30 minutes in and carrying on at regular intervals.
The takeaway
Half marathon fuelling does not need to be complicated.
For runs and races lasting longer than around 60 to 75 minutes, aim for roughly 30 to 60g of carbohydrate an hour, start fuelling early, and practise it repeatedly in training.
There is no one strategy that works for everyone. Your pace, your expected finish time, how your gut copes, your sweat rate and your own preferences all change what works best for you.
By race day you should know what you are taking, when you are taking it, and how your body responds to it.
This article is for general educational purposes and is not individual medical or nutritional advice. Fuelling and hydration needs vary between individuals. If you have specific nutritional requirements, gastrointestinal concerns, medical conditions or a history of low energy availability or RED-S, please seek individual advice from an appropriately qualified healthcare professional or sports dietitian.
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