Marathon training is an exciting yet challenging journey.
You end up dedicating most of your “free” time to training runs, eating right, going to the gym, and trying to get a good night’s sleep so you can get up and do it all over again the next day.
As you build up volume and intensity and reach your peak week two to three weeks from your race, your longest long run awaits you with open arms.
But how long should this long run be? 18 miles, 20 miles, 22 miles? And should you run a marathon in training (the short answer is a definite no, but more on that later).
I wish there were a simple one-size-fits-all answer, but there isn’t. Your longest long run will depend on several factors, such as your running experience and fitness level. Is this the first time you’re running a marathon? Or your fifth?
For a ballpark figure, your longest long run should be between two and a half and three hours. Keep reading as I get into the details so you can calculate your longest long run for your upcoming marathon.
How Long Should Your Longest Long Run Be?
As a certified running coach, one of the first questions new marathon runners ask me is why they won’t run the total marathon distance before their race.
Marathon training isn’t like 5K, 10K, or even half marathon training, where you often run beyond the distance of your goal race. It’s more like an ultramarathon, where you run just a percentage of the race distance.
I can understand the concern, especially for beginners running their first marathon. You may feel that you have to run the entire distance beforehand to feel confident about your performance on race day.
But remember, your training isn’t just about your long run distance; it’s about the accumulated volume week after week.
If you go overboard performing long, taxing runs, it can actually negatively affect your training, fatiguing you and tiring you out before your race. The last thing you want to do is get to the start line with tired legs.
As mentioned, considering factors such as experience and fitness level, training time and volume, and marathon goals, your longest long-run marathon time should be between 2 1/2 and 3 hours.
Depending on how fast you run, this long run could be between 16 and 24 miles. Of course, we will always see exceptions, especially when referring to elite runners.
You’ve probably heard that a 20-miler is usually the sweet spot for most athletes and coaches, but it the reality is it depends and needs to be analyzed on a case-to-case basis.
Working with a running coach is ideal so they can analyze your training as you go and adjust your plan accordingly. They will be able to assign your long-run mileage based on your work up until that peak week. This way, there is much less risk of injury or overtraining.
So, why am I giving you a time range instead of a mile-based answer?
Each runner has their own running pace and will run their marathon at different speeds. Therefore, if we give a specific number of miles, the time on the runner’s feet will vary significantly from runner to runner.
Let’s look at an example.
If you are a beginner running at a 12-minute mile pace, your estimated marathon time will be just over five hours.
If you have to run a 20-mile run for your longest long run, you’ll be on your feet for four hours. Training for that length of time may take too much out of you, leaving your body unable to recover properly.
If you instead decide to stay within the 2:30 – 3:00 hour parameter, your longest run would be more along the lines of 15-16 miles. This is a shorter long run in terms of mileage but not time.
A more experienced runner who runs at an eight-minute mile pace will be able to run the 20-miler in just over two and a half hours. In this case, the runner could perhaps bump up their longest long run another mile or two if their coach decides it’s appropriate and safe.
Jack Daniels, an exercise physiologist and renowned running coach, supports this timeframe, ensuring runners that anything over three hours increases the risk of injury or burnout due to the extra stress on the body.
If you exceed the three-hour limit, your body will need more recovery time, and you may be unable to continue your training program as planned. Overtraining or injury could also prevent you from tapering correctly and force you to take unnecessary time off.
Again, your fitness is an accumulation of all the workouts in your marathon training plan, easy runs, speed work, strength training, cross-training, etc.
If you have followed your training plan to a T, your fitness will pull through and get you to the finish line on race day, even if you don’t run a 20-mile run before the big day.
Let’s discuss ultrarunners for a moment to put this idea into perspective. I’ve been an ultrarunner for the past 12 years and have run a good number of 100-mile and 100K races.
The most my coach had me run before my first 100-miler was an 80K race. That’s only 50% of the total mileage of my goal race.
He told me the same thing I am telling you. It’s not just about that one long run. It’s about all of the volume and work put in leading up to the big day. (In the case of ultras, plenty of back-to-back long runs!)
And guess what, I finished my first trail 100-miler in under 24-hours. It made me a believer in this training method. Your body and mind can do it.
So, trust the process.
What Should My Long Run Pace Be?
As per usual with running, this is going to depend. The intensity at which you should run your long runs in general and your longest long run will depend on your marathon goal.
Are you running your very first marathon or trying to qualify for Boston?
If you are a novice, you should run all your long runs at an easy, conversational pace. Your goal is to cross the finish line happy, healthy, and injury-free. Therefore, your main focus throughout your training cycles will be endurance.
You’ll gradually increase your weekly mileage, with a dip about every three weeks for recovery, with the ultimate goal of building your aerobic base and enduring the 26.2 miles.
If you are an experienced marathon runner, your body has most likely gone through the adaptations of building up your base, and your training program is focused on running faster and at a specific race pace.
If you have a time goal, such as running a 3-hour marathon or 4-hour marathon, you most likely have a precise marathon pace in place.
This marathon pace can be practiced in speed work sessions during the week and during long runs.
I suggest adding it in gradually with easy pace and marathon pace intervals. You could start with 1 mile marathon pace / 2 miles easy pace intervals for the duration of your long run and work your way up from there.
Here is an example of an interval progression if you are going to run a 20-mile long run:
- Repeat 3 times: 3 miles Easy / 3 miles Marathon Pace
- Cool down: 2 miles Easy
If you are interested in estimating your marathon finish time and calculating your training paces, check out this guide: Calculate Your Marathon Pace + Race Pace Strategy.
Expert Training Tips For Your Peak Week Long Run
Even though all of your long runs should be used as mini “practice races” where you try out different fueling and hydration strategies, shoe options, etc., your longest long run is the best opportunity to perfect every detail for race day.
#1: Choose A Route Similar To Your Goal Marathon Course
If you have the option, you want to pick a route for your longest long run that resembles your marathon course.
If it will be hilly, choose a route with some rolling hills. If your course tends to descend, it’s a good idea to know how your legs will feel on those downhills, so choose a route that tends to go downhill.
#2: Carbload The Night Before And The Morning Of
Strategically plan your meals for the day before and the morning of your marathon long run.
You want to eat foods you are confident will agree with you and not cause GI distress, and ensure that you top off glycogen stores with a carb-dominant meal for dinner and breakfast.
Runners can tend to get carried away when they think about carb loading and actually end up overeating. Be careful and just simply replace some of your protein and fat with healthy carbohydrates so you’ll be ready to go the next day.
The same goes for your breakfast the morning of. Make sure you eat 2-3 hours before you start your long run, again, simple carbs such as toast with jam or honey.
#3: Try Out Your Race Day Clothing And Gear
Since this is a practice for your race, wear the same clothing, shoes, and gear you plan to wear on race day to ensure nothing chafes or your feet don’t get blisters or hot spots.
#4: Perfect Your In-Race Fueling And Hydration Strategy
Just like your pre-race nutrition and hydration, you need to practice your in-race strategy on your longer runs.
You should have been practicing all along, trying gels, chews, and hydration options to figure out what works best for you.
Now, during your longest long run you are really putting into practice your perfected strategy.
#5: Recover
After this long run, you are still going to need to train for the next two to three weeks during your taper, so take care of yourself and recover afterward.
Cool down, stretch, and have a post-run snack soon after you finish. Also, ensure that you continue hydrating throughout the day.
If you are looking to get started with your marathon training, we have our very own training plans for every fitness level. Check out our database to choose the right training plan for you:
