How Many 20 Mile Runs Before Marathon

When it comes to preparing for a marathon, there are many factors to consider, including training mileage, nutrition, and rest. One common question that arises is how many 20 mile runs should be completed before the big race. As an avid runner who has completed several marathons myself, I understand the importance of this question. In this article, I will delve into the topic and provide some insight based on my personal experiences and research.

The Importance of 20 Mile Runs

The 20 mile run is often considered a crucial milestone in marathon training. It serves as a gauge of your physical and mental preparedness for the full 26.2 miles. Running for 20 miles in one go allows you to simulate the physical and mental challenges of the marathon distance, giving you a taste of what to expect on race day.

Completing multiple 20 mile runs during your training can help build your endurance, improve your running economy, and boost your confidence. These long runs allow your body to adapt to the demands of running for an extended period of time, improving your aerobic capacity and teaching your muscles to efficiently utilize stored glycogen as fuel.

Factors to Consider

While the number of 20 mile runs needed before a marathon can vary from runner to runner, there are a few factors to consider when determining how many you should aim for:

  1. Your Running Experience: Beginners may need more time to build up to running 20 miles comfortably, while experienced runners may already have a solid base of mileage and can handle more frequent long runs.
  2. Your Training Plan: The specific marathon training plan you follow may dictate the number of 20 mile runs. Some plans incorporate multiple 20 milers, while others focus more on running shorter distances at faster paces.
  3. Your Body’s Response: Listen to your body. If you find that you are consistently fatigued or experiencing excessive soreness after your 20 mile runs, it may be a sign that you need to reduce the number or intensity of these runs.

My Personal Recommendation

Based on my personal experience, I would recommend aiming for at least two to three 20 mile runs before your marathon. This allows your body to adapt to the demands of running long distances and gives you the confidence that you can handle the marathon distance.

However, it’s important to note that every runner is unique, and what works for one person may not work for another. Some runners may benefit from completing more 20 mile runs, while others may find that fewer are sufficient. It’s essential to listen to your body and adjust your training accordingly.


The number of 20 mile runs to complete before a marathon is a personal decision that depends on various factors such as your running experience, training plan, and body’s response. While there is no one-size-fits-all answer, incorporating a few 20 mile runs into your training can be beneficial for building endurance and confidence. Remember, marathon training is a journey, and finding the right balance between pushing yourself and allowing for adequate recovery is key.