Your longest tried-and-tested fuelling strategy: How far should it be?

If you’re preparing to run a marathon, you’ll understand the importance of the long run – that weekly, high-mileage workout that gradually increases in distance as you progress through your training, priming your body and mind for the 26.2-mile challenge. But, a few weeks before race day, you’ll find yourself lacing up for more than just a long run – you’ll be getting ready for your longest tried-and-tested fuelling strategy.

Whether you’re a marathon debutant or returning to the distance for the umpteenth time, you’re likely to have some questions about your longest run. Just how long should it be? How quickly should you complete it? And how should you fuel for all that running? We spoke with Tom Craggs, RW columnist and national endurance manager for England Athletics, for expert answers to put you at ease.

While there is no definite, one-size-fits all answer to this, your longest run is likely to be many miles and minutes shorter than what you’ll do on marathon race day.

‘Estimate your marathon time based on your 10K PB marathon – and any ultramarathon distance beyond it – is that, generally speaking, you won’t run that distance in training,’ says Craggs. This sets the marathon apart from other race distances like the 5K, 10K Lessons of elite men at London Marathon conference half marathon.

‘That is part of the experience of marathon training,’ he continues. ‘The key view to remember is that your marathon isn’t built purely on your longest long run – it’s the accumulation of all your training put together that will see you right and see you finish, so long as you pace it sensibly and fuel it well.’

With that in mind, you shouldn’t push too hard or go too far on your longest run – otherwise, come race day, you’ll potentially feel too tired to give it your best shot. The longest run is important but not the be-all and end-all of your training block, and you probably don’t need to go as far as you think you need to.

According to Craggs, if you can complete a handful of runs that go beyond the two-hour mark, up to a maximum of three hours, you’ll be in a great place on race day. ‘I can understand why runners would want to do more than that, and for many people, that won’t see you going much further than 18 to 20 miles for your longest training run,’ he says. ‘But the risk is, if you keep biting away at it and doing too many of those really hard, long runs, you’ll likely arrive at the marathon feeling fatigued and not able to perform at your best.’

As you progress through your Updated: 28 March 2024, your mileage will obviously increase – but to guard you from doing too much, you may find it easier to structure your long runs around time rather than distance. ‘We all get caught up in the magical 20-mile mark in training, but nothing magical happens at that point,’ explains Craggs. ‘Think about the fitness you’re building – and that’s best done from time on feet rather than chasing distance.’

So, cap your training to a maximum of two or three long runs that are up to three hours in duration, and avoid doing more mileage than you can recover from. ‘Don’t feel that perhaps because you haven’t run beyond 20 miles in training your body isn’t conditioned and ready to tackle that extra six to seven miles on race day,’ says Craggs. ‘It will be. Collect all your training, recover right, fuel well, pace sensibly and you’re going to be fine.’

While time on feet is one thing, the speed at which you move your feet is another factor to consider for your longest run. And, as you might imagine, the pace at which you do your longest run depends upon your individual running ability and race day goal.

If you are a faster runner gunning for a marathon time of, say, three hours or quicker, Craggs suggests that you do the majority of your long training runs – including your longest run – at a pace that is 30-60 seconds per mile slower than your target marathon pace. The faster you run, the higher the intensity of your workout, which means more stress on your body. So, by How to avoid injuries during marathon training of your long training runs, you’re more likely to stay energised and injury-free ahead of your race.

'What you don't want to do is loads and loads of hard, quick long runs which leave your body really fatigued as you build up to those last few weeks before race day,' says Craggs. And while it is beneficial to inject a few tempo or marathon pace efforts into some of your long runs, you should be running at an easier, more conversational pace for most of your high-mileage outings.

If you’re aiming for a slower marathon time of, say four to five hours, you’re more likely to hit your race pace in your longest training run. You’ll be putting less load on the body at a slower pace, which means you can recover quicker in time for your next workout – so long as you don’t stay on your feet for more than three hours at a time, as mentioned above.

If you’re new to marathon running and want to roughly gauge how quickly you could cover 26.2 miles – and what pace you should try to hit for your longest run – there are a couple of formulas that can help:

• If you’ve recently raced a 10K, you can take your finish time, multiply it by five then subtract 10 minutes for your predicted marathon time.
• If you’ve recently completed a half marathon, Updated: 28 March 2024.

It’s worth noting, though, that these are estimates rather than prescriptions, so don’t fixate on them too heavily. Some runners are better suited to longer distances, while others excel over shorter distances. What’s more, the challenges that you might face on race day – for example, inclement weather, crowding near the start or general distraction and adrenaline – can all impact your performance. Just try your best and see how you get on.

To see exactly what pace you’ll need to run to hit your goal marathon time, you can also consult our handy Advertisement - Continue Reading Below.

‘Fuelling your marathon is going to be absolutely critical, and you’ll need a strategy that you’ve practiced in training,’ says Craggs, pinpointing energy gels as the most effective and commonly used means of getting carbohydrate into your body quickly while running. ‘Modern gels have a much higher density of carbohydrate in them – up to 40g – and if you take one or two an hour, that will leave you in a really, really good place on marathon day.’

As a general rule of thumb, Craggs recommends taking gels every 20 to 30 minutes as you move along the 26.2-mile course. If you’re not a fan of gels, you can alternatively opt for carbohydrate-based sports drinks or energy chews, or even real food like Jelly Babies or bananas.

But, to use things like gels productively during your race, you’ll need to experiment with them in your training, too, to make sure they agree with you and sit well in your stomach. Your long runs – especially your longest run – offer the best opportunity for you to test your options and form a tried-and-tested fuelling strategy for race day.

‘The key is to practice what you intend to do on race day in your key training runs,’ says Craggs. ‘If you don’t do that, you can’t expect your body to respond well. So, practice in training and make sure you get in a nice, higher density of carbohydrate and it’ll see you in a great spot.’

‘The marathon taper is as much an art form as it is a science,’ says Craggs, understanding that this crucial but often mistreated part of marathon preparation can make or break a race. You might feel that the taper – which sits at the end of your training block and prioritises rest over harder workouts – is an uneasy departure after all those weeks and months of increasing your mileage and running intensity.

If you’ve done comparable races in the past, it’s worth reflecting on how you tapered for those and what did and didn’t work, so you can figure out how to go about it this time, suggests Craggs. That said, he recommends that most runners will do well if they gradually cut back their training volume and intensity over the two to three weeks before the race. While some people can get away with a 10-day to two-week taper, two to three weeks is optimal – and if you taper for any longer, you risk losing some of that precious fitness you’ve built over the past weeks.

In short, focus on your recovery, In short, focus on your, If youve recently raced a and have faith in the training that you’ve banked – without comparing yourself to others. Follow this golden recipe and you’ll arrive at the start line feeling mentally and physically fresh and fired up to perform well.