How to Train for a Marathon • Common Purpose

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How to Train for a Marathon


Words by Common Purpose Team

Published 21st February 2020

Approximately 9 Minutes Reading Time 


Brief Article Overview


  • When preparing our clients for a marathon, we find Dr Stephen Seiler’s hierarchy of priorities useful.
  • The priority is to simply increase your running miles.
  • Give yourself enough time (16-20 weeks) and gradually building training volume in a strategic manner. 
  • Most of your training should be running, but topping up your training volume with other forms of low impact endurance exercise can be useful.
  • Supplementing your runs with strength training can mitigating your risk of injury.
  • Once you’re comfortable with running distance at a steady state, introducing some high-intensity sessions can help improve your running proficiency, efficiency and race pace.
  • Breaking down the big goal (Marathon) into small manageable chunks and setting “mini-goals” along the way, will help keep you consistent and motivated.


Big Hairy Audacious Goal


We’ve helped many brave souls prepare for marathons all over the world. Each client has unique motivations, histories and needs. As such, we work really hard to meet trainees where they’re currently at and safely develop them to be able to withstand and endure such a long and challenging event.


Although our programs are highly individual, there are a few principles we can apply across the board. These principles have been heavily influenced by the work of Dr Stephen Seiler, a Professor of Exercise Physiology, who is one of the world’s leading experts in endurance training.


Professor Seiler created a hierarchy of priorities that we’ve found to be very practical, thorough and concise. Like all fundamental principles, they can be applied to novice and elite runners alike. Here’s our take on this list of priorities, as well as a case study of how we helped our most recent marathoner! 


Priority #1 | Build your Mileage


Increase Training Volume


First things first, you need to get your miles in. Research on recreational runners found that weekly running mileage was correlated with their ability to sustain higher running speeds. Even elite athletes see their aerobic fitness (VO2max) improve as they increase running volume. If you’re a beginner aim to build to a comfortable 10-15km. Don’t worry about the pace for now, just aim to do the distance without breaks. 


Take Your Time and Build Slow


So it’s clearly well established that increasing training volume is important. This process, however, needs to be a gradual one. As explained in our “Training Through Pain” article, exposure to training stimuli is a bit like sun tanning. You’ve got to slowly build up your tolerance to the impact and stress of running long distances, allowing enough time for your body to recover and adapt.


The biggest mistakes we see, especially amongst first-time marathon runners, is not giving themselves enough time to prepare, going too hard, too fast and ending up injured. 


Give yourself enough time to build the miles over the course of your training program, for a beginner going for their first marathons, we recommend a minimum of 20 weeks prep time. Start off low and slow. If you’re already in the thick of it, then a good rule of thumb is to limit your training volume increments to 10-15% per training week (if time allows!).


Utilise Low Impact Activities 


Although a large majority (at least 80%) of your training should be spent running, a nice way to increase training volume whilst keeping injury risk low is incorporating different exercise modalities.


Swimming, cycling and rowing, for example, allow you to rack up the miles and hours without overly exposing your joints to the repetitive impacts associated with running. Using these exercises on top of your running to further improve your cardiovascular fitness, may come in handy. These activities are also advised if you encounter an injury. Use them as part of your rehab to retain the aerobic fitness you’ve worked so hard to gain.


Priority #2 | Stay Strong!


This is a key aspect of the “injury-free” component. As much as some endurance athletes dislike it, adequate strength is crucial to protect the joints. In order to tolerate so much volume, you need an equal blend of fitness, strength and technique.


Improving the ability of your muscles to absorb and produce force in a well-coordinated manner does brilliant things for your running economy. Appropriate and relevant strength training should not be overlooked and should be seen as an important supplement to your endurance running training. 


Did you know that every single foot strike requires the absorption of 2.5x your body weight?


This doesn’t mean you need to start powerlifting 5 times a week! You just need to ensure that your joints, ligaments, tendons and muscles are both resistant to fatigue and maintain integrity under load. We suggest two full-body strength training sessions a week, focusing on developing the entire lower body chain and midsection. 


Here are some examples of our favourite strength exercises for runners: 


Offset KB Bulgarian Split Squat (click for video)

Single-Leg Romanian Deadlift with Knee Drive (click for video)

Farmers Carry with Knee Drive (click for video)

Priority #3 | Pick up the Pace


Types of High-Intensity Training


Once you’ve racked up the miles and are comfortable with running distance (10-15km for example) at a steady state, you might want to think about pushing your pace and introducing some HIT (High-Intensity Training) and or HIIT (High-Intensity Interval Training).


For sports specific outcomes there is a real need for specificity. That is, keep the activity the same (in this case, running) but increase the intensity by manipulating either speed or resistance e.g. sprints, hills or sledges.


Interval Training


So how long and intense do the intervals need to be if your training for a marathon? The literature does suggest that there’s a sweet spot for maximal transferable gains, which seems to be just above the anaerobic threshold (zone 4 or 80-90% of max heart rate). This is the intensity at which fatigue builds exponentially after a few minutes. If you don’t know your anaerobic threshold we recommend using a heart-rate zone training calculator as an initial estimate. 


Intensity and duration recommendations depend on your current fitness levels. But in general when training for an endurance event like the marathon, aim for relatively long intervals (4-8 minutes).


Repeat these intervals 3-6 times. Start with a work to rest ratio of 1:2 (4-8min on 8-16min off) then progress to 1:1 (4-8min on 4-8min off), then finally 1:0.5 (4-8min on 2-4min off).


The idea here is to push this ‘fatigue point’ known as the “lactate threshold” back so that eventually you’ll be able to run at a faster average pace without fatiguing. We suggest you buy yourself a good heart rate (HR) monitor (visit this article at Jen Reviews for a comprehensive guide on how to buy the right monitor for you) and give it a go! 


Pre-Race Tempo Runs – A Finishing Touch


About 8 weeks out from your marathon, just before your 1-2 week taper (gradual reduction in training volume), it may be beneficial to introduce 2-3 “tempo runs”. Also known as threshold runs, these are essentially the midpoint between steady-state (aerobic system dominant) and HIT (anaerobic system dominant). The intensity is right at the point between the two energy systems (70-80% MHR, between HR Zones 3 & 4), known as “comfortably hard”.


A few of these runs before your marathon will help add the finishing touches to your physical and mental preparation. An example for a marathon prep would be 15km at between half-marathon and marathon race pace, or (for added mileage) a 20km marathon pace run followed by 8km between the half marathon and marathon pace. Two of these within the final 6 weeks before your 1-2 week taper should be sufficient. 


Priority #4 | Finding the Balance


Polarised Approach


Building upon this notion of training at different zones and intensities, it begs the question of what zones should I train in and for how long? The evidence seems to bias toward a “polarised approach”, that fluctuates between both ends of the spectrum, as opposed to constantly hanging around the middle. Of course, there are real and logistical challenges. 


For example, we don’t want you sprinting down Regents Street at rush hour to get your extra two minutes of Zone 5 work! It also builds upon the first priority when it comes to volume. We’ve got to find ways of either increasing how much you’re doing or how hard you can push.


Priority #5 | Periodisation Details 


Breaking your goal down into manageable chunks is crucial when trying to conquer something like a marathon. How do you eat an elephant? One bite at a time. Setting a coherent framework that follows basic scientific principles (progression over time), aimed towards a SMART goal; completing a marathon, in a specified time is a great start. 


The more intricate the details within this plan, however, the more they can disappear into obscurity. So don’t overthink it, any progressive periodisation model will do. As Seiler states, all these different models are just scientific ways of saying “variation, variation, variation”. 


Think of consistent progression as the big rock of your program and planned variation (intensity, modality etc.), as the small pebbles which keep you interested, motivated, may accelerate the process and give you an edge when it comes to race day.


Below is a nice representation of the interaction between progressive exercise bouts, adequate recovery and fitness improvements which is a series of super-compensation cycles over time. 

Case Study


At Common Purpose, we typically work in four-week blocks and employ a stepwise loading where possible. This is done by increasing on weekly basis either intensity (speed, perceived exertion, load, impact) or volume (distance, time, reps, sets).


In our most recent marathon preparation client, we sat down and broke up her training into monthly targets. She had 6 months to prepare for her marathon, this is the macrocycle. We broke this down into separate months and assigned goals for each of them. 


For example, in February we made it about working up to 15km run. March the aim was to run a personal best 5km. These are known as mesocycles. These months were then broken down into weeks and days (microcycles).  


The microcycles are basically how we manage training Monday through to Sunday. Training distribution must be centred around the event practice itself. In this case the long run. This is worth considering when incorporating supplementary activities such as strength training. 


As a general rule of thumb, we recommend waiting for 48h between higher intensity sessions. See for recommended set-up for a runner who’s looking to prepare for a 10km run.


Here’s a week out of her training program: 

Try and consider how your longer bouts fit in with your week as they are often quite time-consuming. But they’re so worth fitting in. There are so many benefits physically and mentally to derive from a long run, cycle or even a big hike on a Sunday morning.


Big Picture Thinking


Simply put, some planned variation is better than monotonous training, and any form that has you do more and/or push harder over time is crucial, whilst also allowing for things like adequate sleep, recovery and restoration.


Many things influence a coach’s decision making. Things like the trainee’s history of training, history of exposure to different sorts of stress and load, psychological states, health and metabolic states.


Social and environmental models also affect the output of the system. Little things like access to good outdoors environments suitable for your activity. Nonetheless, I think all coaches can agree that there are some principles worth using guidelines such as understanding the relationship between volume and intensity.


We love coaching our clients through specific, challenging events like the marathon, so let us know if you’re thinking about it by dropping us a message! 


If you’re interested in starting your health and fitness journey with us…

Disclosure: This article is not to be used as medical advice. If you are currently experiencing physical or mental health issues, please seek professional advice from a fully qualified Nutritionist, GP or Physiotherapist.



  1. What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes? Seiler, Stephen. (2010). International journal of sports physiology and performance.