18 Week Marathon Training Plan + Complete Guide For Intermediate Runners

Whether you are training for your first marathon or fiftieth marathon, are trying to break five hours or qualify for the Boston Marathon, or want to run as many miles per week as possible or as few as you can get by with while still having a good race, you need a great marathon training plan.

In this article, we have created an 18 week marathon training plan for intermediate runners who would like to train for their first marathon or try a different approach to marathon training than the previous marathon training plan you used.

We will look at: 

• How Long Is a Marathon?

• 18 Week Marathon Training Plan For Intermediate Runners

Let’s jump in!

How Long Is a Marathon?

A marathon is 26.2 miles or 42.195 km long.

18 Week Marathon Training Plan for Intermediate Runners

We designed this 18 week marathon training plan for intermediate runners who have an interest in training for their first marathon.

The marathon training plan is designed to be approachable to runners who have some endurance built up but have yet to take on any formal marathon training. You will need to be able to run 6 miles without stopping before taking on this program.

If you are not yet up to that distance, consider our Couch To Marathon, 6-Month Marathon Training Plan, or 20-Week Marathon Training Plan for beginners.

These will be more beginner-friendly marathon training plans.

The 18 week marathon training plan below is designed to be unintimidating if you want to run your first marathon. There are no track workouts. You will do some speed work, but it is in the form of Fartlek runs.

These can be done on the road, trails, or even on a treadmill, so if you do not want to have to go to a track or you feel anxious about timing yourself on a track, a fartlek run is a great way to work on your leg turnover in a more relaxed way.

Like most marathon training plans, you will gradually progress the distance of your long run, and you will do some tempo runs and a little bit of marathon pace work.

The cross-training workouts in this 18 week marathon training plan are also important to reduce the stress on your musculoskeletal system while still improving your aerobic fitness.

Here are a few tips for the workouts you will find in this 18 week marathon training plan for first-timers:

• Cross Training: Any form of non-running aerobic workout. Examples include cycling, swimming, rowing, elliptical, aqua jogging, and hiking.

• Distance Run: Base-building run to improve your endurance. These should be run at a comfortable pace—something around a 7 out of 10 on a rate of perceived exertion scale or a heart rate around 70-75% of your maximum heart rate.

• Fartlek Run: Distance run involving bursts of fast running (think 5k race pace or faster) without stopping. Take 30-60 seconds of easy running in between each interval based on how you feel.

• Easy Run: Run at a conversational pace to aid recovery from harder workouts. These should be a 6-7 on an RPE scale.

• Strides: Accelerations or sprints at an all-out effort at the end of a run. Walk to recover.

• Long Run: Long endurance workouts to improve physical and mental stamina.

• Threshold Workout and Tempo Run: Run at a pace you can sustain all out for one hour.

If you’re looking for an intermediate, advanced, or time-based marathon training plan, check out some of our other free online marathon training plans.