The Marathon Training Series: Building Mileage for Long Runs

The Marathon Training Series: Building Mileage for Long Runs

By rabbitPRO Eric Senseman

The fall season might seem far off–after all, more than half of the summer season still remains. But if you’re planning to run a marathon this fall, now is the time to start gearing up.

When it comes to building up your weekly mileage, and the length of your weekly long run, there are two rules of thumb that are often used. 

  1. First, there’s the ten percent rule: Increase your weekly mileage no more than 10% from the previous week. Accordingly to this rule, if you run 30 miles this week, you shouldn’t run more than 33 next week. 
  2. Then, there’s the twenty-to-thirty percent rule: Your weekly long run should compromise 20-30% of your running volume for the week. According to this rule, if you run 30 miles this week, your long run should be 6 to 9 miles. 

A consequence of these two rules is that if you want to increase the length of your weekly long run, then you need to increase the number of miles you run each week–but only at the conservative rate of ten percent. Unfortunately with this math, depending on where you are in your running fitness, it could be sometime in 2024 before you’re ready for a marathon.

Rules of thumb are great, but rules are also meant to be broken. While these rules can be useful for a well-trained athlete at the peak of her training, they’re less helpful for the average marathoner looking to get ready for a race this fall. To determine how to safely build your mileage for long training runs leading into the fall, here are three questions to ask yourself:

  1. Are you returning to running after an injury? 
  2. Is your current weekly volume close to the highest weekly training volume you’ve run in the past six months? 
  3. How many days of the week are you currently running, and what’s the most days of running per week that you’ve done in the past six months?

If your answers to questions 1 and 2 are yes, or you’re running six or seven days each week, then the 10% rule and 20-30% rule can be applied. If not, take those rules with a grain of salt and consider including the following tips to build your mileage for long training runs. 

  1. The art of doubling. Running twice per day can safely increase weekly volume. For beginner-to-intermediate runners, or for any runners not accustomed to doubles, this should only be done once per week to start. Adding an easy four-mile jog in the evening might not seem like much. But, in the example above, if you’re currently running 30 miles per week, this small addition would bump you to 34 miles–or a 13% increase in mileage. Note that twice-per-day running shouldn’t take the place of a long run. 
  2. Isolate your long run. Running with fatigue is a good skill for a long-distance runner, but doing so in training too often can lead to overtraining, burn out, or injury. As you begin to increase the distance of your long run, keep those long runs isolated. That means taking a day off either before or after the long run,  running short and easy either the day before or after the long run, or a combination of these. 
  3. Ditch the intensity. As noted at the start of this article, summer is alive and well. In gearing up for a fall marathon now, you’re laying the foundation for a specific block of training this fall. As such, the summer focus should be on volume rather than intensity. As you increase your weekly volume, and the duration of your long run, keep your effort under control and just run easy. 
  4. Increase by twos. Two miles isn’t too far for a marathoner. Physiologically, two miles is a good number to tack onto your long run week after week, and it’s short enough that it doesn’t balloon your long run from a small number one week to a large one the next. If you start with an eight-mile long run and add two miles each week, six weeks later your long run will be eighteen miles. If you start now, summer will come to an end in the course of those six weeks, and you’ll be ready for your fall marathon training block. 

However you approach your training, make sure you listen to your body and slow down or take days off if you need to so that you stay injury-free. Happy running!