As a UKA Registered Coach in Running Fitness, my most popular and intriguing distance to offer advice on is the marathon. I am firmly in the camp of running 20-22 miles as your longest run in training. If it were me (a 3:46:40 PB marathon runner), I wouldn’t want to be on my feet for any longer than 3 hours. I would run 18 x 2, 20 x 3 and a 22 miler (all being well and according to plan) 4 weeks out which would see me on my feet for a little over 3 hours.

On top of this, I would incorporate a 10-12 mile mid-distance runs during the heavier weeks with the majority of this at marathon pace as well as my speed training and easy miles.

I have been in this camp for years – then I met and started living with my partner – a sub-3-hour marathon runner at the same time as making friends with another couple, one of whom is also a coach. Then began the great debate – ‘Should you run a marathon to train for marathon?’ My answer – there is no need. It will take you too long to recover, your body shouldn’t be running marathons that often. His response – How do you know you can run the distance if you don’t run the distance? While I agree with this sentiment for a half marathon – I don’t for a full distance.

The Experiment

Anyway, after debating this one night, my partner stated that he was going to do it. He would run the distance to see if it helped/hindered his training. Of course, there was no way we were going to advise doing it at his usual pace and we agreed to do it in two stages – half with me at 9 minute mile pace and half on his own at 7 min mile pace.

And that is exactly what he did – in fact, at the end he barely looked like he had broken a sweat! He rested for the rest of the day and woke up the next day feeling good. No leg soreness, no DOMs. I should point out he has a physical job so is on his feet all day anyway.

His thoughts

  • He took it easy for the first half and only upped the pace a little in the second
  • He had lots of water before, during and after which he feels definitely helped
    He fuelled properly before, during, and after and was able to test his hydration and fuelling
  • The last 3 miles was where it got tough and he felt like that was the point where he was getting the biggest training benefit

So, this is all great but we still don’t know the long-term effects – how will he fair when he toes the line for the London Marathon in 6 weeks? Will this particularly long run help or hinder him? How will his tune-up half marathon go in a week? All of these questions we are yet to answer.

Many of his fellow sub-3 marathon runners have tried and tested the same and gone on to pull a PB out of the bag by incorporating this distance into the training and as they said “it’s never done them any obvious harm”.

Do I still think it’s not a great idea?

I certainly wouldn’t advise it. It takes a lot out of you and it’s tough on the body but I can see the confidence boost that it has given him which is perhaps the biggest benefit.

The benefits of running a marathon to train for a marathon?

Will the fact that he ran the full distance prepare him for how it feels to do the full distance on the day? Will those last 3 miles be a little less difficult because his legs know what it is like? Will the pain be a little less?

There are some who say that the 26-mile distance as a training run offers very little benefit, that it can prevent you from optimal training for 10-14 days after. Here is why, and many others think you should NOT be running the distance in training:

Marathons Are Tough On The Body

When you tackle a marathon, every part of you gets put to the test both physically and mentally – from muscles to tendons to ligaments, and beyond. Whether you’re cruising at a leisurely pace or pushing yourself to the limit, those 26.2 miles take a toll on your body like no other. Here’s a rundown of some of the key physiological systems that bear the brunt of the challenge after you’ve conquered that marathon distance:

Running a marathon takes a toll on your skeletal muscles, leading to soreness and fatigue. Research shows that both training for and completing a marathon can cause inflammation and muscle damage, impairing muscle power and endurance. Even if you feel fine after the race, your muscles are weakened and require substantial recovery before resuming full training.

After a marathon, cellular damage can be assessed by measuring creatinine kinase (CK) levels, indicating harm to skeletal and myocardial tissue, and elevated myoglobin levels in the blood. Studies have shown that CK damage can persist for over a week post-marathon, while myoglobin remains in the bloodstream for 3-4 days after the race. These findings emphasize the importance of rest for the body to recover fully from the cellular damage incurred during the marathon.

Recent research indicates that the immune system experiences significant depletion following the completion of a marathon, heightening susceptibility to colds and flu, particularly for those continuing rigorous training for upcoming races. Additionally, a weakened immune system stands as a leading factor contributing to overtraining syndrome.

Although running at an easy pace can mitigate some of the detrimental impacts of marathon running, research unequivocally demonstrates that the marathon causes notable damage to muscles, cells, and the immune system for a period ranging from 3 to 14 days following the race.

Is there any additional benefit than a 20-22 mile long run?

Most marathon trainees typically maintain a pace ranging from 8 to 11 minutes per mile during their long runs, aiming for a finish time between 3:30 and 5 hours. For instance, running at a 9-minute mile pace, a runner would spend approximately 3 hours completing a 20-mile run.

While a 20-mile run (or longer) can undoubtedly boost confidence, it might not offer significant training and physiological benefits.

This is because research reveals that the prime physiological stimulus during long runs occurs between the 60 to 90-minute mark, with diminishing returns thereafter. Consequently, aerobic benefits such as capillary building, mitochondrial development, and myoglobin levels plateau or even decline after the 3-hour mark. Hence, completing a marathon distance as a long run doesn’t necessarily enhance fitness beyond what a typical 20 to 22-mile run would achieve.

There is also an increased risk of injury with extended mileage. Despite the seemingly small difference between a 20-mile and a full marathon distance, each additional mile significantly amplifies muscle fatigue. In the final stretch, typically the last 4 to 6 miles, form deteriorates, major muscles weaken, and overuse injuries become more prevalent, even at an easy pace. This heightened risk of injury is particularly notable among novice runners whose aerobic capacity may surpass their musculoskeletal readiness, meaning their bodies aren’t adequately prepared to withstand the demands placed on them, despite their lung capacity.

And for those who are all for it?

Training for a marathon by running a marathon itself may seem counterintuitive, but it can be a strategic part of some training programs. This approach is often referred to as a “marathon simulation” or a “dress rehearsal” run. The purpose is to replicate the race-day experience as closely as possible, allowing runners to test their pacing, nutrition, hydration, and mental strategies in a controlled setting.

During a marathon training cycle, runners typically complete long runs of varying distances, with the longest runs typically reaching up to 20-22 miles. However, these runs may not fully prepare runners for the physical and mental challenges of covering the full marathon distance of 26.2 miles.

Running a marathon as part of training provides several benefits:

Mental Preparation: Completing the full marathon distance during training can boost confidence and mental resilience. It allows runners to experience the physical and mental highs and lows they may encounter on race day, helping them develop coping strategies and mental toughness.

Pacing Practice: Marathon simulations allow runners to practice pacing strategies and find their optimal race pace. They can experiment with different pacing approaches and learn how to adjust their pace throughout the race to avoid hitting the proverbial “wall” or burning out too soon.

Nutrition and Hydration Testing: A marathon simulation provides an opportunity to test and refine nutrition and hydration plans. Runners can experiment with different fueling strategies, hydration schedules, and types of energy gels or drinks to determine what works best for them on race day.

Race-Day Logistics: Running a marathon during training allows runners to practice race-day logistics, such as pre-race routines, gear choices, and transportation to the start line. It helps minimize surprises and ensure a smoother race-day experience.
While running a marathon as part of training can be beneficial, it’s essential to approach it with caution, especially for novice runners or those prone to injury. Proper recovery is crucial after completing a marathon simulation, and it’s essential to listen to your body and adjust training plans accordingly to avoid overtraining or injury. Additionally, not all marathon training plans include a marathon simulation, and there are alternative approaches to training for the marathon distance.

At the end of the day, everyone has their own opinions – it is a subject that divides people. In a recent Instagram poll, we got 67% against and 33% for. It is fair to say that many more people disagree with the theory than those that do. Will it work for you? Will it work for my partner when he runs London? We will certainly be reporting back with a full rundown on his training programme (which is over halfway through now).