Can you run a marathon and train for an Ironman® at the same time?

Can you? Yes. Should you? Maybe not.

This question typically exists for a group of people training for their first Ironman® triathlon race who have also never completed a marathon before.

There’s a prevailing wisdom that you should have accomplished at least a stand-alone marathon before attempting an Ironman®. If that stand-alone marathon happens before your Ironman® training block even starts, then that’s one thing – the problem comes when people consider doing a marathon while actively training for an Ironman®.

There exists a small number of reasons why you can or should shove a marathon into your Ironman® training, but for those in their journey to complete their first full distance triathlon, there’s a longer list of why it should be avoided.


In order to run a marathon, you need to have run the miles in training.

Typical marathon training plans have you peaking at a 20 mile run some 2-3 weeks before race day, after having slowly climbed up to that mileage throughout many prior weeks of progression.

After a marathon, the average recommended (reasonable) recovery time for the average athlete is 2-3 weeks of light, easy activity.

Can you start to see the issue?

If you wanted to put a marathon into your Ironman® training schedule, you’d either have to:

  1. Tack it on after the training plan works you up to 20 miles (witch is only a few weeks out from your actual Ironman® race, and wouldn’t supply a necessary amount of recovery time – and would greatly impact your cycling/swimming training too), OR…
  2. Put it closer to the beginning of your training plan, requiring you to ramp up running miles well before a solid base is built

Both options put you in compromising positions for being able to A.) properly train cycling/swimming and/or B.) recovering enough before your actual race.

Recovery needed

I mentioned that the average recommended (reasonable) recovery for a marathon is 2-3 weeks.

That means, for a normal person who trained for a marathon running anywhere from 25-40 miles per week in training, is probably going to be mega sore after a marathon.

The first few days thereafter you won’t do much, and maybe you can start to jog, lift, do yoga, etc. about a week after the race, but it certainly won’t be at any high intensity.

That downtime between the marathon and when you’d be able to begin again ‘normal’ triathlon training at the necessary volume & intensity, can put a large damper on the quality of that subsequent training. Simply because of fatigue & injury risk.

A marathon and an Ironman® marathon are not the same

The main reason people consider doing a marathon during their Ironman® training is because they want that marathon experience.

Well, news flash, unless you’re an elite runner – they don’t translate all that well.

Think about it.

A stand alone marathon, you start mile 1 fresh as can be. You’ve got pace targets, and can properly anticipate how your body will begin to fatigue over the 26.2 miles because that race is the only factor in determining how you feel.

With an Ironman® marathon, for the vast majority of first timers – this is a point of survival.

How you feel, and what your pace ends up being – depends heavily on how the swim and bike went.

Consider that you’ve had a 6-9 hour warmup leading up to your marathon start line. Things like weather (was it hotter or colder than expected?), nutrition (how’d your stomach do on the bike ride?) and fatigue (you’ve covered 114.4 miles already!!) really dictate how your marathon goes.

So while it’s nice to have covered 26.2 miles before – it doesn’t mean that your experience will be the same (or even similar) after that 114.4 mile “warmup”.

Your first marathon can be your Ironman® marathon

It’s ok – really it is.

There are hundreds (probably more) of people who jumped into long course triathlon long before running a stand alone marathon – and made it across the finish line just fine.

The key is to stick to a training plan that takes into consideration proper mileage and volume progression of the 3 sports. Trust that you’ll be ready on race day, and put your energy into properly training, vs tacking on unnecessary practice races.

Practice races of Olympic & 70.3 distance are going to me much more transferrable to your full Ironman® race because of that fatigue factor, than any stand-alone race will be.

So if you’ve never run a marathon before, and you’re working towards your first Ironman®, don’t worry – you’re not alone.

Trust the process, follow your plan, get some shorter triathlon races built into your season, and you’ll be just fine.

It’s simply not worth the risk of injury or deterioration of your other sport training to try to knock both out in the same training plan.