Should You Run A Marathon During Marathon Training?

Running a marathon takes months of training with weekly long runs. But on those long runs do you ever run the full marathon distance? 

In shorter races like a 5k, 10k or even a half marathon you might cover the full race distance in training runs, but it’s rarely done in marathon training. Why is that?

Whether you sign up for a race or do the distance on your own, what are the positives and negatives of running a marathon as part of your training?

Here’s the top line you need to know:

Running the full marathon distance in training for a marathon can work for some well-trained and experienced runners, but is an unnecessary risk for most other runners. Instead, it’s smarter to focus on completing several quality long runs up to 20-22 miles/32-35k.

LONG TRAINING RUNS

The distance of a marathon isn’t necessarily the issue here; it’s not like 26.2 miles is a barrier after which your body cannot continue. Just look at ultramarathons where you’ll likely do training runs of more than 26 miles. 

The key consideration is that in training for a marathon, running the full distance in advance isn’t essential to success in the race. You just don’t need to do it, and there are potential negative associated with running that far, but it is something that runners choose to do. 

WHY RUN A MARATHON AS PART OF MARATHON TRAINING?

There are several reasons why someone might do a 26.2 mile or 42.2k run during marathon training. 

• Some runners like to know that they are able to run the full distance in training ahead of a goal marathon race. 
• Experienced and well-trained runners may choose to do a full-distance or even over-distance (i.e 27 miles, 45k) to get good physical and mental preparation for race day.
• Some experienced runners like to sign up for numerous marathons during a year, while others like to book two marathons within 4-8 weeks of each other to give themselves two chances at racing a goal time using the fitness from the same training block.
• Sometimes we just plan our routes wrong and end up running further than planned.

NEGATIVES OF RUNNING A TRAINING MARATHON

• It’s a long distance to run so you need to make sure your body is fit and strong enough to handle it and, importantly, be able to recover in order to continue training the next week.
• You may need to factor in more rest days and easy days in the week after running a training marathon, which may affect your overall training – adding a few extra miles to a long run could end up causing you to miss more cumulative miles in the next weeks, probably outweighing any benefits.
• Very long or very hard runs can affect your immune system (runner’s flu is something a lot of runners suffer from after a race) and that could lead to having to take time off training towards your goal race.

POSITIVES OF RUNNING A TRAINING MARATHON

• Running a marathon in training removes the intimidation of the distance.
• It’s a good chance to practise the full marathon experience including the carb-load, race day travel, race fuelling and race kit.
• Some runners love to race often so plan training marathon races in the build up to goal events.
• It can be a good way to develop physical and mental resilience.

IF YOU CHOOSE TO DO A MARATHON AS A TRAINING RUN THEN:

• Only do it if you are a well-trained runner who is well-experienced at running marathons (and probably a faster runner – you don’t want to be doing long runs of over four hours, whether that takes you 42k or 24k).
• Use it as a full dress-rehearsal for your race with one key difference: the intensity of your run. Don’t do the full distance at goal race effort and start out at an easy pace, increasing to race pace near the end if you feel good.
• Don’t be afraid to stop early if you aren’t feeling good. Cutting a run short or stepping off the course for a DNF may be smarter than derailing the next few weeks of training.
• Ensure you carb-load well and make the most of mid-run fuelling and post-run recovery.
• Factor in additional recovery time and be prepared that you may need to adjust an entire week of training following a particularly hard run.

One alternative to thinking in distance would be to do a longer ‘time on feet’ run. If you’re a runner aiming for under 3:30 in the marathon then you could do a run which takes 3:30-4:00 and is run slowly or on trails. This can be good condition for the amount of time a marathon will take you without going the full marathon distance. But again, you need to factor in great nutrition and additional recovery.

HOW TO RUN TWO MARATHONS CLOSE TOGETHER

Some runners choose to sign up to two marathons within 4-8 weeks of each other. Sometimes this is just because they want to run a couple of races, other times it’s as a chance to use the same training block to have two attempts at a goal time. Here’s how to do that.

Focus on a full week of recovery after the first marathon. Do some active recovery and walking, eat well, sleep well, and prioritise recovery, and only do easy runs if you’re feeling good. 

If you have four weeks between races: after an easy week, in the second week try to do one or two shorter workouts to get your legs moving again. For your long run that week, aim for 14-18 miles (23-30k) if that feels ok for you, but don’t push too hard if you’re still feeling fatigued. Keep running shorter workouts, or workouts with goal marathon pace in the next weeks as you taper down again.

If you have six to eight weeks: you have time to have a couple of easy weeks and then a couple of weeks with some more quality running and intensity. Get a good mix of workouts in the week and then two or three good long runs during this time, then taper again to your race. 

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Here’s Sarah on her longest run in training for the 2024 London Marathon