When should I progress my mileage? By how much per week?

Author: Becky Arturo, PT, DPT, CSCS, RRCA Running coach, USAT Triathlon Coach

Running a marathon is huge feat. Regardless of what happens on race day, the accomplishment lies in the journey and training you complete in order to toe the start line. When training for a marathon, it’s important to train enough but also to train safely. Mileage progression is a major component of safe and complete marathon training.

Prior to building up to your marathon, you should make sure to build up a good running base. This means starting to log consistent miles on your feet prior the start of your official marathon training build. For someone who can run for at least an hour during this base building phase, I recommend a 4-5 month build up to your marathon.

When progressing mileage, it’s important to follow the 10% rule of mileage (or time) progressions. This means that week to week, you should not increase your weekly running time or mileage by more than 10% of the previous week, and I even tend to decrease this rule to 5% when returning from injury. 

It’s important to keep in mind that as your long run distance or time is increasing, your week day mileage should also be increasing with mid-distance runs and workouts. 

You should also take a step-down week every 3-4 weeks to allow your body time for recovery and adaptation. In general, this means decreasing your mileage and intensity for the week, and keeping your long run to 90 minutes or less. 

While some runners train by distances, others train by time running some use a combination of long runs by time and week day runs / workouts by distance. Either method is fine, as long as you follow the above-mentioned 10% rule of progressions with step downs. It is generally not recommended to do long runs of longer than 3-3.5 hours, as running for that long can have diminishing returns and increased risk of injury, especially for newer runners or first-time marathoners. 

You do not need to run more than 18-20 miles to finish a marathon, but if you need longer than 3-3.5 hours to get to that mileage, some coaches will recommend doing back-to-back long runs, such as 8 miles in the evening followed by 12 miles the next morning. Other coaches recommend getting out for the full 18-20 miles at once for the psychological training, while understanding the injury risk and diminishing physiologic returns. 

One more thing to keep in mind when planning your mileage progressions is that you should plan for a 2-3 week taper prior to race day. This means your longest run and highest mileage week should be 2-3 weeks before race week. After that, I recommend cutting mileage and intensity by 25% per week leading up to race week with a 3-week taper, or slightly more with a 2 week taper.

Committing yourself to marathon training is a great accomplishment in itself. Make sure you maximize your success with proper training and progressions along with adequate recovery!