When it comes to long endurance runs, especially the marathon, the decision isn’t so much “to carb or not to carb”, but rather how to go about it.

 

Personal preference

We all have certain products we naturally gravitate to, whether it’s because we saw them before the alternatives, or it’s an informed decision having tried other options. It’s important to consider personal preference when it comes to working out your marathon fueling strategy, but equally to get the best result will sometimes mean going outside of your comfort zone.

 

Question your previous experiences

A lot of people I talk to and coach have tried some gels and found they caused a stomach upset. Upon further discussion though, they’ve revealed that they didn’t have them until 45-60 minutes into the race, or even later. This is far from optimal, and is likely why they experienced some unpleasant symptoms. It wasn’t the gels so much as the condition their body was in when they ingested the gel.

 

Optimal fueling

Many of the most popular products from SiS and High 5, often used because they’re low-cost and stocked in supermarkets and stores such as Holland and Barrett, are far from optimal when it comes to their carbohydrate content since they only contain glucose-derived carbs. If we continue with the gel analysis in particular, both of their main products suggest using one every 20-30 minutes. If you stick with this even, which most people won’t, you’ll still be missing out on your best performance due to a lack of fructose.

Comparisons of athletes in 3 exercise trials showed that whilst glucose only carbs of up to 60g/hour improved power output by 9% on average vs. taking on no carbs, if fructose at 20-30g/hour was also added, power increased by 17% vs. the control group who had no carbohydrates.

I don’t know about you, but if something safe and legal like a gel could give me up to 8% more power than an inferior gel, I’d be swapping as soon as I could! In fact I did, transitioning from using SiS gels to Torq gels through 2020 into 2021.

 

Other carb options

Although I drink mostly water and squash on long runs and marathons, carb drinks such as Tailwind (which does supply glucose and fructose in the ideal ratio) can be a good option.  There’s only really one, potentially major, drawback. Your carb fueling and hydration are then linked. 

If it’s hot and you want to drink lots, you could end up with too much carbohydrate to use and get a stomach upset. Too cold and not wanting to drink, and you could end up missing out on carbs or drinking so much you need to stop to use the toilet because you’re not sweating it out, and you lose time.

You don’t necessarily need to pick only one option, you can of course use gels and drinks to fuel, but calculating and executing that strategy is more difficult and open to mistakes.

 

Bars and chews

I’d generally advise not bothering with these for marathons unless you’re looking at 4 hours or more as your target time. Even then, the chewing could well disrupt your breathing and slow you down where gels or drinks could get you round well.

 

As always, there’s no one correct way to fuel your marathons, but consider what I’ve told you when it comes to formulating your race day strategy. Don’t forget to try it out a few times before the big day to see how it feels and allow yourself the opportunity to change things if you need to, or allow your body to adapt to taking on more carbs.

 

Written by Kyle Brooks, Running Coach based in Norwich, Norfolk