The long run is the most important part of a marathon training plan. It’s the key training run for marathoners during their training period, ending with the longest long run.

The longest long run marks the end of intense training and the beginning of a taper, which lets the body recover and get ready for race day.

Many runners worry about the longest long run and wonder how long it should be. 

Different training methods suggest different approaches – some focus on time, some on mileage, and others on weekly volume. Some plans even have runners run the full 26 miles in their longest long run.

The answer to how long the longest long run should be isn’t a simple straightforward answer. It depends on various factors like your running experience, your injury risk, and, your goal finish time

In this article, we are going to help you determine how long your longest run should be. We will break down:

  • The Purpose Of The Long Run In Your Marathon Training 
  • How To Run A Long Run
  • When And How Long Your Longest Long Run Should Be
  • The Shortest And Longest Long-Run Options In Marathon Training

So, let’s get started…

What Is The Purpose Of The Marathon Training Long Run?

The purpose of a long run is to achieve several outcomes, with the most important one being building your base endurance or overall endurance. It helps your body develop the ability to supply oxygen and energy to your muscles during the marathon.

Long runs also play a significant role in improving running economy, especially when training for much longer distances. 

It helps the body get accustomed to being on the move for extended periods and psychologically prepares you for longer distances.

These runs prepare you mentally to be on your feet for a long time and make your tendons, ligaments, and muscles stronger. 

Additionally, these long runs provide an excellent opportunity for you to experiment with nutrition. You can try different fueling strategies to see what works best for you and what you can tolerate on race day. 

During long runs, take it easy and enjoy them. It’s not about speed or how fit you are. Save performance tests for your time trials. 

You should be able to comfortably chat with your running buddy during these runs.

Running long distances increases the blood vessels in your muscles, making oxygen and energy delivery more efficient. 

However, running even more beyond a certain point (around 20-23 miles or 32-37 km) doesn’t provide extra benefits. It can lead to injuries, so it’s not worth the risk.

How Do I Run A Long Run?

When it comes to running a long run, the key is to approach it with a smart strategy. 

As mentioned earlier, long runs are essential for building endurance and stamina, but they should not be tackled too aggressively. 

The importance of not running too hard during long runs cannot be stressed enough. Running at a pace that’s too fast can leave you feeling exhausted and drained, making it challenging to complete the run. 

Instead, opt for a more relaxed and easy pace that allows you to sustain your efforts throughout the entire run. 

It might even feel a bit slow, almost like it could get boring, but that’s exactly the pace you should be aiming for. The goal is to finish the long run feeling like you could have gone a little further, not completely wiped out. 

By maintaining an easy pace, you’ll be able to keep going for longer and make the most of your training. 

Here are some common mistakes many runners make during their long runs.

Common Mistakes You Should Avoid When Doing Long Runs

Common Mistakes You Should Avoid When Doing Long Runs

Running Too Hard

One of the most significant mistakes many runners make during their long runs is running too hard. Long runs are not about testing your speed but rather building your endurance. You should aim to finish your long run feeling good, not completely shattered, and be able to continue your training the next day without feeling overly fatigued.

Increasing Mileage Quickly

Another common error is increasing the mileage too quickly. It’s crucial to gradually increase the time spent on your long runs to reduce the risk of injuries. Jumping to longer distances too soon can be harmful to your body.

Stopping Too Often

While taking walk breaks during long runs is recommended, stopping too often or pausing your watch can provide false data. 

Remember that each runner is unique, and what works for one may not work for another. It’s essential to find the right mileage and pace that suit your body and fitness level…

Related: Get Better at Running: 10 Common Mistakes to Avoid

What Determines Your Longest Long Run Time?

The length of your longest run depends on factors such as your running experience, injury risk, and your goal finish time. 

Marathon training plans vary from person to person, with some runners finding an 18-mile or 30 km long run less taxing compared to others. 

At Coach Parry, our approach emphasizes planning long runs based on the duration of time you spend on your feet, rather than a fixed distance.

If you’re already accustomed to handling long runs or have a higher weekly mileage, you might find it manageable to extend the length of your long runs.

Conversely, if you’re new to running or have a history of injuries, it’s advisable to space out your long runs to every two weeks instead of doing them weekly.

That said, it’s important to remember that the value lies not just in a single long run, but in the cumulative volume you build each week. 

Many runners worry that their longest training run isn’t as long as the full marathon distance – and that’s okay. The key is consistently accumulating weekly volume, steadily building it week after week.

Now that we’ve covered much about long runs, let’s take a closer look at the timing of your last long training run before the Chicago Marathon.

When Should Your Last Long Run Be Before The Chicago Marathon?

Finding the right timing for your longest run before the Chicago Marathon is crucial to ensure you reap its full benefits and be race-ready. 

Running too close to the event can lead to excessive fatigue on race day, while doing your longest run too far in advance may not maximize your training gains.

Here’s a timing suggestion based on your running ability and experience:

Novices (If You’re New To Marathon Running)

If you’re new to marathon training, aim for your last long run about 4 weeks before the Chicago Marathon. This allows enough time for recovery and tapering before the big day.

Intermediate And Advanced Runners (If You Have Some Experience In Marathon Running)

For those with some marathon experience, schedule your last long run approximately 3 weeks before the race. 

This balance provides adequate recovery while maintaining your fitness level.

Elite runners

If you’re an elite runner, such as a sub-3-hour marathoner, you may consider adjusting the timing slightly closer to race day based on your personal preferences and what works best for you.

Now that we have the timing sorted, let’s focus on the pace you should aim for during your longest run.

Finding The Right Balance For Your Long Runs In Your Marathon Training

At Coach Parry, we believe in striking the right balance with your longest training runs for the Chicago Marathon. 

While these runs are essential for your preparation, overly long runs may not always be the most effective approach.

Here’s why:

Length And Timing:

The ideal length and timing of your long run should be tailored to your race goal and running experience. It’s essential to adjust these factors to suit your specific needs and abilities.

Diminishing Returns And Potential Damage:

There comes a point in your longest training run where the benefits start to diminish. 

Pushing beyond this threshold may lead to potential damage, compromising your training in the weeks leading up to the race, and even on the race day itself.

Here’s a comparison showing the differences for your longest run leading up to the Chicago Marathon according to your race goal:

Longest Run Distances & Pacing For The Chicago Marathon

(Please note that these distances are subject to change depending on how your training progresses. We want you to be well-prepared and ready to conquer the Chicago Marathon!)

Race Goal TimeLongest Run TimePace RangeAmount Of Weeks Before Race Day
Sub 3 Hour3:00 Hours4:25-5:10/km (7:06-8:19 min/mile)3 Weeks
Sub 3.30 Hour3:30 Hours5:15-5:50/km (8:27-9:23 min/mile)3 Weeks
Sub 4 Hour3:15 Hours5:45-6:30/km (9:15-10:28 min/mile)3 Weeks
Sub 4.30 Hour3:30 Hours6:25-7:05/km (10:20-11:24 min/mile)4 Weeks

In conclusion, it’s essential to recognize that the mileage for the Chicago Marathon is individualized. 

Each runner responds differently to the same amount of mileage, so comparing mileage with others may not be helpful. Instead of getting caught up in the mileage comparison game, it’s better to focus on your own needs and capabilities.

NB. If you have concerns about your mileage, it’s safer to lean towards doing slightly less rather than pushing yourself too hard. 

Trust the Marathon training plan you’ve chosen, have faith in the process, and remember that not all advice applies equally to everyone.

To ensure your success, we offer a 12-week Chicago Marathon Training Roadmap, based on proven science, to guide your training. 

This plan outlines your daily training and the optimal pace for each session, helping you avoid injuries and ensuring you’re well-prepared for race day.

Although there may be ongoing debates on this topic, rest assured that the Coach Parry plan provides a reliable and effective approach to preparing for the Chicago Marathon

So, let’s put any doubts to rest and focus on achieving your best performance on race day!

Should You Run 26.2 Miles/42 Kilometers Before Running The Chicago Marathon?

No, it’s not recommended. Running that distance can stress your body and increase the risk of injury, affecting your race performance. 

Remember, your training is not just about one run; it’s about the hard work you’ve put in throughout your journey.

To be ready for race day, focus on optimizing your training. 

Long runs are essential, but doing the full marathon distance before the event may not be the best approach. Instead, follow a well-designed training plan that gradually builds up your endurance and fitness level.

As you approach the Chicago Marathon, remember that your training accumulates over time. Give yourself enough time to recover and avoid overstraining. 

The key is to trust your training, take care of your body, and be well-prepared for the big day. 

With consistent effort and a balanced approach, you can reap the full benefits of long runs and perform at your best on race day.


Devlin Eyden has a passion for seeing his athletes grow and excel. From novice runners or cyclists across all disciplines to elite mountain bikers representing South Africa at World Championships. In addition to helping you ride faster, for longer, Devlin also has the personal touch when it comes to your bike setup, aiming at improving the overall rider experience. With his background as a Sport Scientist as well as a Strength & Conditioning specialist, performance is Devlin’s main priority, be it in the gym, the lab or out on the road or trails. Being a keen runner & cyclist and having completed the Cape Epic among others, Devlin has first hand experience in what it take to reach your goals. If you’re looking for a once-off training program or ongoing, high touch support Devlin has you covered.

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