How To

Zwift How-To: Running a Marathon on Zwift

on February 05, 2021

Running a marathon is hard. Depending on how good your treadmill is and how well-ventilated your indoor space is, running a marathon on Zwift may be even more difficult than outdoors!

So how do you do it? How do you train for and complete a full 26.2 miles of running on Zwift?

Treadmill Experience

Running on a treadmill is an acquired skill. When you first step on a treadmill it can feel slightly strange. Having the Zwift screen to focus on can help with this, but it's certainly something you need to get used to before deciding to run long.

The more comfortable you become running on a treadmill, the more energy-efficient you will become. And that is vital if you are going to spend upwards of 3-5 hours running on Zwift in one session!

Treadmill Quality

There is no escaping the fact that the better your treadmill, the better your Zwift experience is likely to be. This also translates to indoor marathon running.

If you have an old or very basic domestic treadmill it’s going to demand more energy from you to finish the marathon. An old treadmill belt will stretch more as it warms up and may also create increased friction underfoot. The motor may not be powerful enough to keep you moving at a set pace consistently and this will make your run feel much more difficult.

By contrast, a quality treadmill will feel closer to outdoor road running. Your effort level should be almost comparable. You won’t feel like you are constantly fighting the treadmill.

Learn about choosing a treadmill that works with Zwift

Running Environment

The most common issue when comparing indoor running to outdoor running is the buildup of heat and the lack of airflow in the room where your treadmill is situated. Treadmill running feels more difficult indoors because you are generally running in a hotter environment. As a result, your heart rate increases and your body is under greater stress.

You can mitigate this with open windows, plenty of fans blowing cold air onto your body and, if practical, choosing a cold day on which to run your marathon. Keeping cool, especially in the latter stages of your marathon, will help minimize fatigue.

Learn all about staying cool on Zwift

Marathon Training

It’s not essential to have run a marathon outdoors before attempting a marathon on Zwift.

Regardless of your time goal, marathon training consists of the same basic elements. The only difference is the volume of mileage you will be doing. Each week you should do these sessions

  • Long Run
  • Flat or hill Interval Session
  • Speed Session
  • Easy Runs

Your long run should be done at an easy, conversational pace. Don’t be tempted to push at marathon pace. You should try to increase the distance of your long run each week, so that 3-4 weeks before your marathon attempt, you complete at least one run of around 20 miles.

Interval sessions will improve your overall speed. You can alternate flat intervals with hill intervals to spice things up. Your speed session should be an all-out effort over 3-5km. These sessions are great to do on Zwift because you get the encouragement and support of others during the intervals sessions and you get competition in Zwift races to motivate and push you for the speed sessions. These hard sessions should leave you feeling completely exhausted.

The easy runs should be done like your long run, at a conversational pace. Anywhere between 5 and 10 miles is sufficient. Do not neglect these runs. They are vital for building your aerobic base, helping you to run longer at a lower heart rate, which means less effort and more efficiency. You can do as many of these as you like each week!

Marathon Pace Training

It seems counterintuitive that in marathon training you are not constantly running at your goal marathon pace. The problem is, running at goal marathon pace is taxing on the body. Too much training at race pace will quickly tire your body, risking injury and burnout.

Instead, every couple of weeks you can build some marathon pace efforts into your long run. If your long run is, say, 14 miles, you could do either the middle 7 or the last 7 miles at marathon pace. But do not do the whole effort at marathon pace and don’t do it in every long run.

What is Marathon Pace?

Even if you have no desire to finish your Zwift marathon in a specific time or run at a specific pace, it is still prudent to set a realistic goal time and plan to run at a specific pace. This will undoubtedly help you finish.

Remember, efficiency is the key. Running ‘even splits’ or the same pace for each kilometer or mile will keep your heart rate stable and your body moving in a consistent and steady manner.

This will conserve energy for later in the run. Continual fluctuations in speed and cadence are disruptive both physically and mentally.

Choose a finish time that is realistic based on other races or runs you have done. There are lots of tools you can use for this such as the McMillan Pace Calculator. Enter your current 5k, 10k, or half marathon time and it will suggest what kind of time you might be capable of achieving in the marathon.

If you are looking at running a 4-hour marathon, your pace should be 9.09min/mile or 5.4min/km. Running this on a treadmill is simple enough. You merely dial in the pace and leave it there until the end.

Don’t be tempted to start fast to ‘bank’ miles. It could be beneficial to start slightly slower to ‘warm’ into the run. But in general, you are better off staying at the exact same pace all the way. Only if you feel super good in the last 5k should you think about increasing your speed!

How Many Miles a Week?

There are many schools of thought about the best ways to train for a marathon. If you are planning to do a marathon on Zwift then you should divide your training between the treadmill and outdoors.

One of the accepted truths about marathon training is that volume and consistency are key. Volume is the number of miles you cover each week. Most experts agree that to run faster in a marathon one of the main components is mileage.

In order to be in the right physical shape to run a 5-hour marathon, you should be running between 20 and 40 miles each week consistently for approximately 12 weeks.

For a 4-hour marathon you should plan for around 40 to 60 miles a week, and for a 3-hour marathon 60-80 miles a week is likely required.

The increased mileage should mostly be in the form of easy runs. Your training should not include more than 2 or 3 hard sessions a week.

Of course, this assumes you have some level of basic fitness and you are not starting from scratch. Brand new runners should build in some months of ‘base’ exercise to prepare their bodies for the intense level of training they are about to undertake.

Join a Group Marathon

Running a marathon, especially on a treadmill requires not only physical fitness but also mental strength. Much of that mental fortitude comes from your own confidence, experience, and personality. But a large part can come from the support and encouragement you get from those around you.

This is equally true on Zwift, where there is a huge community of like-minded runners, all wishing you the best and pushing you on to achieve your goals.

You may prefer to run your marathon alone, as a solo activity on Zwift. However, you will feel a greater sense of community spirit, an increased sense of responsibility, and a huge motivation to succeed if you enter a group run.

Having others around you running a marathon at the same time on Zwift is incredibly inspirational. Hang on to that inspiration, perhaps stick with a runner who is going at your pace, suck in those Ride Ons, and hand out a few of your own as you go. The miles will go by quicker.


Running a marathon on Zwift doesn’t have to be more difficult than running one outdoors, if you have the right equipment and get your running environment right. If you do the training and embrace the Zwift running community, it might even be easier and more fun than you expected! See you in Watopia.