How many kilometers/miles should you run a week to prepare for a marathon?

How many kilometers should I run per week to properly prepare for my next marathon? That's a question we've been asked so often, but the answers are often unclear. At Campus, we're not going to give you a random number. We'll help you understand the challenges surrounding mileage for marathon and determine your ideal preparation based on your individual profile.

Though it's a legendary event, the marathon is a distance that is both demanding and accessible to a majority of runners, provided they put in the effort. Preparation over several months will train your body to sustain continuous effort over 42.195 kilometers/26.2 miles. Whether you're looking to complete your first marathon without a time goal or aiming for your personal record, preparing for a marathon is always an unforgettable adventure.  

To improve endurance running, simply run more. This is even more true for the marathon than for shorter formats such as the 10K or the half-marathon, which are run at higher heart rates. 

However, the development of your aerobic capacity is very gradual. This is the one you will be relying on almost exclusively in the marathon. It is after several years of training and numerous milestones reached that you will develop this capacity to its maximum.  Alongside the frequency of your runs and weekly volume, the length of sessions can also increase. 

This creates a virtuous circle: "the longer you've been running, the longer you can run". That's why a good base of kilometers run at a slow pace is essential to prepare for your marathon and to arrive in the best conditions on race day. 

One of the main challenges in marathon is to resist muscle and joint fatigue that occurs in the second part of the race. All runners, regardless of their level, have experienced that moment when their body urges them to slow down.  

Good preparation will allow you to push this fatigue back as far as possible. By accumulating a good amount of miles, you'll train your body and mind to better navigate this critical point in the race. That's the whole point of a long-term preparation. A training plan of 16, 20, or 24 weeks will allow you to progressively achieve a good weekly mileage volume with a significant number of long runs ranging from 1 hour 45 minutes to 2 hours 15 minutes. All this while respecting rest days and assimilation weeks. 

In 2019, the Strava app collected data from male and female runners during the last 12 weeks of their marathon preparation, and categorized them according to their time goals. These figures provide indications on the mileage to cover according to your own goal. 

This goal concerns the vast majority of runners. The weekly kilometer/ mile range recorded by Strava for men and women is 30 to 42 kilometers, with at least 3 weekly runs completed. Below this frequency, you'll be advised to focus on shorter distances. In practice, your marathon preparation will lead you progressively up to 40 to 50 km (24,85 to 31,07 miles). It's a good indicator whether running a marathon is a good idea considering your volume: having run the marathon distance in a week before attempting it for the first time. 

About 40% of men and 20% of women aim to finish under 4 hours. To target this goal, the weekly average increases to 51 km for men and women, and a minimum of 4 runs per week. This type of preparation can lead to a max volume ranging between 65 and 70 km. 

Here, we're dealing with a minority of runners since only 5% of finishers manage to finish under 3 hours (4% of men and 1% of women).

During the London Marathon, Strava was able to analyze the kilometer volumes recorded on their platform. An interesting metric emerged: finishers under 3 hours trained about twice as much as finishers between 3 and 4 hours. 

The number of kilometers per week increases at the same time as your weekly long run. Your long run will mainly depend on your distance goal and your ability to gradually extend it. At Campus, the potentially longest session does not exceed 2 hours and 30 minutes. From our point of view, this is the best compromise to develop your endurance while minimizing the risk of injury and incomplete recovery. 

The number of kilometers/miles gradually increases until week -3, generally the busiest week of your plan. The fatigue level is then at its maximum, intentionally. Then, the mileage decreases progressively in the last few weeks. This is the tapering period. By maintaining your workout frequency but reducing the session volume and slightly their intensity, your fatigue will decrease, and your fitness level will increase. Logically, you will reach your peak fitness in the final week, ready to give it your all.

It is important to thoroughly master the pace you will target on the day of your marathon. For amateur athletes, these sessions are not the ones that lead to the most progress, but they provide benchmarks for race day and thus build confidence. This type of session includes intervals run at marathon pace. The intervals, relatively short at the start of preparation, will increase over the weeks. Here, we aim to improve your running economy, that is, to use as little energy as possible at your marathon pace. It will be interesting to perform this type of session with legs already fatigued by your previous training to simulate the last ten kilometers of the marathon. 

The essential session of a marathon training plan. It will have a major impact on your physical condition and boost your confidence at the starting line. In the early stages of preparation, your long run won't be much longer than your usual jog, and it will gradually increase over the weeks. Ideally, don't add more than 2 kilometers/1,24 miles or 10 minutes extra each week to limit the risk of injury. You must not push your body too hard as it needs to assimilate the stress generated by this unusual effort. 

Depending on your goal, your level, your weekly volume, and the duration of your plan, the long run will peak between 25 and 35 km a few weeks before the marathon. Reaching this peak will require several months of adaptation. That's why Campus recommends preparation durations longer than the “traditional 12 weeks,” especially for first-time marathon runners. 

In the Campus plans, the maximum duration of long runs is 2 hours 30 minutes, even 2 hours 40 minutes for the most experienced profiles on the longest plans. A longer duration is considered counterproductive. It increases the risk of injury, generates too much fatigue, and requires too much recovery time. It's not so much the duration of your longest run that will change the outcome of your race, but rather the amount of long runs you've fully assimilated throughout your plan. 

The general idea is to smooth your effort to the maximum in order to avoid changes in
pace that are costly in energy. This is the energy you'll need at the end of the race. Oftentimes,
with the excitement of the start and the adrenaline peak, runners tend to
start too fast, well beyond their marathon pace, and regret it afterwards. Do you want
to give yourself the best chance? So follow this precious advice from seasoned marathoners
: the marathon really begins after 30 kilometers. Up to that point, it's better to
stay focused on your split times.

About 80% of the weekly mileage in your marathon preparation is run at a base endurance pace. A comfortable pace at which you should be able to hold a conversation without effort. Easy runs are made for this and allow you to accumulate kilometers without generating additional fatigue. Conversely, spinning your legs in complete relaxation can contribute to your recovery after more challenging workouts. 

These sessions consist of alternating between fast phases (faster than your marathon pace) and recovery phases. The benefits of interval training are numerous, from the improvement of endurance, to muscular power, or technique. They are useful whatever your goal. After these sessions, your marathon pace will feel much more comfortable!

Preparation for a marathon generates fatigue. It's normal, it's even one of the intended goals. However, be careful not to exceed certain limits unique to you. Your running background, reference times, predisposition to injury or not, and your ability to recover well are all indicators that will influence the mileage your body can handle. The important thing is to find your sweet spot, the right balance that allows you to progress without overdoing it. The Campus plans are individualized to adapt to your specific needs. 

Recovery plays a central role in a marathon preparation. Remember that it's the training + recovery combo that allows you to progress, and that rest days are essential. Whatever your profile, it is advisable to observe at least one complete rest day a week to regenerate physically and mentally. 

Many factors affect your recovery, such as your lifestyle, sleep quality, diet, hydration, or even your age. All these factors will affect the maximum training load your body can handle. 

The beneficial effects of muscle strengthening in a marathon preparation are well-established. It can be beneficial to keep one or two slots in your week reserved for strength & conditioning (calves, quadriceps, hamstrings, ankle, foot). Ideally, these sessions will complement your training plan. Starting with 4 or 5 weekly running sessions, if you're prone to injuries, it may EVEN be considered to replace a workout with a strength & conditioning session.

To top it off, now that you've grasped all the subtleties of the volume to achieve in your marathon preparation, you can launch a custom Campus plan...  No need to calculate your weekly mileage, we'll handle it! :)