How to Train for a Marathon (From 12–16 Weeks Out)

As a preface to this article, I’m generally talking about the sub 3 hour to sub 4 hour marathon runner. Someone that’s been running a little while and stepping up to their first marathon, or someone a little more seasoned who’s got 2 or more under their belt and stepping back to the plate for a more competitive time.

On the presumption that you are actually training for your marathon, and not missing training by sitting on the couch- most marathon runners who fall short of their goals (or worse- don’t make the start line) don’t fall short because they didn't train ‘hard’ enough, they fall short because the training they are doing is not optimised to their ability, and there is usually mis-aligned expectations of where the goal time outcome sits in relation to that ability. I call it- ‘’the body and the mind not being in the same neighbourhood!’’

If a runners' training is not optimised for their actual ability as it is TODAY, then they are not going to be getting the specific training stimulus and adaptations that they are looking for in order to have a good performance on race day. E.g if you’re a 3:30 marathoner and following a training schedule for even a 3:15 marathoner- you WILL NOT be getting the full benefits of that training. Worse- you’ll be over-reaching. At a basic level you won’t even be getting the specific aerobic adaptations as even your easy pace will be too fast.

I see it all the time. The excitement of entering a marathon quickly turns into chasing bigger long runs, higher weekly kilometre totals and harder sessions than are actually necessary. 12-16 weeks out from race day, runners are already trying to train like they're in the peak of their marathon block. These are the runners that typically get sick or injured 4-6 weeks out from race day-either not realising their potential, or not even making the start line.

One of the principles I keep coming back to as a Coach is this: You can only get so much adaptation from EACH training block. Gain potential is not linear or exponential. You can't force six months worth of training into sixteen weeks just because you feel like it or you think ‘I’m different’.

Prefer to Listen?

If you prefer listening over reading, we unpack these same coaching concepts in this week's NZ Nomad Runner podcast. We discuss marathon training in more depth, share examples from coaching, and explain why we structure marathon blocks the way we do.

🎙️Listen here 

12-16 Weeks: Continuing on with that foundational work

The 12–16 week window is one of the most misunderstood blocks of marathon training. Many runners think this is where they need to start proving they're ready. In reality, it’s where they're preparing themselves to tolerate the training that is still to come.

This is still a foundational phase. Yes, the long run begins to extend, weekly structure becomes more deliberate and you're transitioning from simply ‘running’ to genuinely ‘training’. However, the emphasis should still be on consistency rather than hero sessions. This means, we want to be plugging together the entirety of our training schedule in a pragmatic fashion week to week. We’re getting a little tired at certain parts of the week, but we’re able to recover well and be ready for the next week to rinse and repeat.

Your body should be adapting to training, not surviving it, you don’t want to be accumulating too much fatigue at this point and you should be ticking through these weeks with relative ease still. If you’re not- then your training load is either too high for you as an individual, or you need to look at what other interventions can be introduced in order for you to be able to tolerate that training load- that is the two levers that can be pulled.

This period is also a great opportunity to continue building strength. As the marathon-specific work increases later in the block, there is naturally less capacity for heavier strength training. So at this point you might be doing 2 pretty solid strength sessions per week, whereas closer to your race for most athletes marathon training it will be more like 1 key session per week with some shorter lighter functional routines scattered through the week.

Key themes for this 12-16 weeks out:

• You’re levelling up your foundation
• Getting your body strong
• Deepening that aerobic base
• Dialling in the discipline of your training routine
• Looking after yourself, keeping things simple
• You’ve increased your carb intake and are fuelling your runs with purpose
  

Consistency Will Always Beat Hero Sessions

One of the biggest mistakes I see is runners chasing sessions that look impressive rather than sessions that produce adaptation. A huge king hit long run might earn plenty of kudos on Strava, but it doesn't necessarily make you a better marathon runner. I'd much rather see an athlete complete twelve weeks of consistent training than four incredible weeks followed by injury or illness.

Marathon fitness is remarkably patient. It rewards runners who continue turning up week after week who train within their ability, rather than those who try to cram everything into a handful of sessions.

Brick by brick. That's how good marathon performances are built.

The 8–12 Week Window: Bridging Towards Marathon Specificity

Around the 8–12 week mark, training begins to shift.

Long runs continue to increase in duration, and marathon pace work starts to appear within some of those runs. Not huge race simulations, but enough to begin teaching your body what marathon intensity feels like under fatigue. Often I prescribe something like 15-30 minutes of marathon intensity at the end of the weekend long easy run, especially around that 10-11 week out period, then I often prescribe a de-load week around 9 weeks out.

I call this 8-12 weeks out a bridge phase, because that is exactly its purpose: To bridge the 12-16 week phase with the final 8 weeks. As a coach when I’m working with someone I’m really looking to prepare the athlete well for the final 8 weeks (9 weeks incl race week). I want them to be strong, very aerobically fit, healthy, niggle free, relatively fresh, and mentally fired up for the final 8 weeks.

Together we’re also building a picture on where we are starting to see marathon pace (or marathon intensity) landing for the upcoming sessions, we have a good idea of this already as we’ve accumulated a lot of data by this point and we have a strong feedback loop going back and forth.

Key Themes for the 8-12 week window

• Think about this phase as a bridge
• Aim is to get to 8-9 weeks out from race day feeling strong, healthy, niggle free and mentally fired
• Start to get an idea of where marathon pace for upcoming sessions is starting to land based off of your data and how training has gone to date

The Final 8 Weeks to Race Day: Where it all comes together

Everything before this point has been preparing you for the final phase of the marathon block- the final 8 weeks. If you haven’t got the foundation work done in the preceding blocks and your marathon goal isn’t realistic in terms of your ability, you WILL be getting found out in this period!

This is where the training becomes much more marathon and event specific. Long runs become more demanding, marathon pace sessions become more substantial, fatigue starts to accumulate.

BUT- if you have built that strong foundation in the preceding blocks and you’ve been moving through your training and recovery pragmatically, then you’re going to get the most out of this final 8 week block and you’re going to get the maximum adaptations from that marathon specific pace work.

Your body is going to be strong enough to tolerate it, and you’re going to effectively absorb it and adapt from it efficiently.

I always have a de-load week up my sleeve that I use with my athletes around that 5-6 weeks out from race week period. This leaves you with 2 deliberate blocks within that final 8-9 week phase of training. Train, absorb, train!

This sets the athlete up for success for that final push. 4 weeks and 3 weekends out from race day your able to get some big punchy long runs with nested marathon intensity efforts included. It also means your able to hit taper period and still sharpen up with some shorter runs with a little

intensity- vs just being cooked and surviving till race day!

Key Themes for final 8 weeks:

• Your generally looking at 4-5 key long runs that contain some marathon pace work
• The length of the marathon pace blocks vary a lot, but taking out the outliers- you’re looking at 5km/6km/8km/10km reps athlete depending.
• Example: 34km run with 3 x 6km at Marathon intensity….. or 28km with 1 x 10km at marathon intensity, and 1 x 5km below marathon pace. Many ways to skin it.
• If your self training start with 2 x 5km reps within your long run (on the assumption you’ve done some mid week marathon pace work in prior blocks)
• Keep life simple, no new life commitments or projects if possible
• Look after your body, fuel the machine, do all the little maintenance protocol, recover like a pro, and prioritise sleep

Learning From Your Own Training

Perhaps one of the greatest opportunities during marathon preparation is learning more about yourself as an athlete. Every training block teaches you something new, we are forever gaining more insights about ourselves and our running, all of which we get to take forward into future training cycles.

You get to understand how much training you tolerate before fatigue accumulates, how your body responds to marathon pace work, what nutrition allows you to recover well and how your confidence changes as fitness develops, or how it can sometimes take a hit when one of those key sessions don’t go to plan. Don’t worry- usually there is at least one of those in any block!

This is one of the reasons I encourage athletes to reflect on their training rather than simply completing it. The marathon rewards runners who understand themselves, not just those who follow a schedule. Using tools like Training Peaks to do this is great, as you can comment on your runs-how you were feeling that day, how the run went, how you’re generally going

that week. That is all valuable data you can look back on in the future with or without a coach if you self train. We use Training Peaks to prescribe for our athletes at CMF Running, sometimes it can be 1 year down the road on a Zoom session with an athlete and we’ll go back to a prior marathon block and be able to dial right into how things were going in that phase thanks to the back and forth comments we’ve had in Training Peaks. This helps us shape current and future training.

Final Thoughts

Marathon training is about making consistently good decisions over an extended period of time.

I often say to my athletes: ‘We want to get all the dials pointing the right way’ This means keeping things simple, looking after ourselves, having training set that achievable and right for us, our ability, and that fits into our life, and just move through it pragmatically.

Avoid the temptation for Strava glory in training. Training by definition is about practice, learning, simulation- that’s what we want be doing. Race day is where we get to shine and lay it all out there. So often I see Strava glory from individuals in training, then see them fall short in race day execution. Often that’s the athletes I end up coaching!

The marathon has a way of exposing shortcuts. It rewards patience, consistency and good judgement. Those qualities aren't particularly exciting, but after coaching many marathon runners over the years, they're the characteristics I see most often in athletes who completely fulfil their potential in the marathon and all aspects of their running.

Key Takeaways

• The earlier blocks are about preparing you for that final 8-9 weeks
• Prioritise consistency over occasional hero sessions.
• Allow marathon-specific work to develop progressively throughout the build.
• Practise your race nutrition, pacing and equipment well before race day.
• Don't compare your training to other runners—your marathon and your training is unique to you.
• Judge your marathon build by months of training rather than individual workouts.
  
• Use every marathon campaign as an opportunity to better understand yourself as an athlete.
• Don’t chase weekly km totals, just cause someone said you gotta hit x kms on a group run
• Think about your key long sessions first in duration, and work the prescription to distance from there

About the Author

Chris Lucas coaches runners and athletes who are serious about levelling up their running. He also develops and mentors the CMF Coaching team, helping shape the coaching philosophy behind CMF Running. He's the host of the NZ Nomad Runner Podcast and is passionate about helping runners better understand the why behind their training.

Keep Learning

If you enjoyed this article, here are a few more coaching resources to help you continue learning.

🎙️Podcast: How to Train for a Marathon (From 12–16 Weeks Out)

📖 Related Article: Training Apps vs 1:1 Run Coaching

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