How To Run More Trail Mileage Safely

As a trail runner, living in a mountain village is a privilege. Every day provides the opportunity to run on nearly endless trails right from my front door. It seems as if the only thing that limits me from running on some of our mountain trails is that I can’t run far enough to reach them. The quest is to increase my trail mileage so that I can explore those further away trails. The question is how much can I increase my running volume without getting injured?

The general rule for running is to only increase mileage by 10% each week. However, the 10% rule fails at both very low mileage and very high mileage. Low-mileage runners can be more aggressive. At high mileage, runners must be more conservative and only increase mileage every 2 or 3 weeks. 

Let’s take a closer look at the factors that will help you determine the optimum rate that you can increase your trail mileage safely. 

How To Run More Trail Mileage Safely

There was something that my athletics coach always used to tell me, the easiest way to get injured was running too fast, too long, and too soon. What he effectively meant by that is if you ramp up your mileage and intensity of your training too quickly you get over fatigued, you don’t recover enough to assimilate that training that you’ve done, and that inevitably leads to some sort of overuse injury. 

So the way to increase your mileage safely on the trails is to make sure that you’re not increasing your mileage by more than what you are physically capable of assimilating and recovering from before you head out on your next training run. Because it’s not during a massive training run that you get injured, it’s when you set off on the next training run without having properly recovered that your injury risk skyrockets.

The 10% Rule For Safely Increasing Trail Mileage

We all know the general “rule of 10%” for increasing mileage safely whether it be on the road or on the trail. However, while the 10% rule is a really good system, especially for beginners, there are two instances where the 10% rule does not really work all that well. The first of these is when you’re doing really low mileage and the second of these is when you doing really high mileage. 

Let’s start off with what happens at the low mileage end of the spectrum. For someone who is relatively new to running or restarting after a layoff, you might be doing three runs per week and each one of those runs is about one mile and distance. If you were to increase your mileage by only 10% each week you would only add about 150 yards to each of your runs by 150 yards.

This is far less than what you’re able to step up on a week-to-week basis. For instance, at that rate, you will not be able to expand out from three to four runs per week of one mile each for over two months and a half and that is far less than what you’re capable of ramping up your distance. As you can see, when your mileage is still really low you should be able to safely increase your mileage by more than 10% per week by adding an extra run day without aggravating your chances of getting injured. It does help to have a coach who monitors your recovery levels – or use a Whoop Band (available on Amazon).

On the flip side, if your current mileage is already around 90 or 100 miles per week a 10% increase in mileage week of the week will be way more of an additional training load than what your body is capable of handling and you will very likely get injured even if you stick to the 10% rule. 

So, as you can see from this, if you are currently at a high mileage level you will do better by increasing your mileage by substantially less than 10% in order to be able to stay healthy.

Be Strategic With Trail Running Mileage Increases

As you can see, it is important to be more strategic with your trail running mileage increases. If you’re relatively new to trail running or are restarting, you should be able to increase your mileage by easily more than 10% each week – even potentially in the region of 20% each week for the first few weeks and then gradually dial that percentage down in a way that I’ll explain to you in just a moment.

Likewise, you need to be strategic if you are already up at the high end of the mileage spectrum. It may be more prudent for you not to increase your trail mileage by 10%. Either reduce that weekly percentage or increase your mileage by approximately 10% every second or third week rather than every week. That way you are giving your body more time to adapt to the new training volume.

Know Your Baseline Mileage

One of the most important things to know as a trail runner is your baseline trail mileage. What I mean by this is the mileage per week that you feel comfortable running at when you are approximately mid-season, fully fit, and not yet ramping up for a goal race.

By knowing your baseline mileage you will know the level to which you can ramp up your mileage more rapidly without the risk of injury. By way of example, if your normal baseline mileage is 50 miles per week and you have just completed a marathon or a half marathon and have taken a week for recovery. You can’t restart your training back at 50 miles a week after the week of recovery as it will be too great of a shock to your system.

However, even if you restart your training at 20 miles per week, or even less, you’ll be able to increase your weekly mileage back up to your baseline of 50 miles per week within 3 or 4 weeks. This is simply because 50 miles per week is what you already know your body is capable of handling comfortably. You just need to be able to ease back into that comfortable distance after having recovered from the race you did.

Likewise, if you know your baseline mileage, you will know that as soon as you start pushing your mileage above that baseline you should do so at a more conservative rate than the 10% rule that we mentioned earlier. It is at these mileages that are above your baseline will you start pushing yourself into the territory where you need to balance your recovery to mitigate injury risk.

Aggressive Trail Mileage Increases Up To Baseline Levels

As I mentioned earlier knowing your baseline mileage means being able to ramp up your mileage quicker after recovering from a race during your season. Similarly, if you are at the start of a new season you can be more aggressive in the increase of your weekly mileage back up to your baseline level.

Conservative Trail Mileage Increases Above Baseline Levels

Once you are above your Baseline level, it is prudent that you become more conservative in the rate at which you increase your run mileage. The simple reason is that above your baseline you can become somewhat more injury prone if you don’t manage recovery carefully. 

One thing to remember is that each injury-free season allows your baseline mileage. So, by being more conservative in your weekly mileage increases once you’re above your baseline level, you are making it possible to have a higher baseline level for each successive season.

Prioritize Distance Over Pace For Additional Miles Above Baseline Level

When I am increasing my mileage above my baseline level, I have build weeks and maintenance weeks. A build week is one where I increase my mileage. During my build week, I prioritize the additional mileage over pace or any intensity workouts.

My maintenance weeks are those where I stabilize at the new higher mileage. Here is where I incorporate some quality workouts into my program again.

Limit Number Of Targeted Workouts During Mileage Build Phase

As I mentioned earlier, when you are in a mileage-build phase, you should limit the number of targeted/quality workouts during that base-building phase. For instance, when I’m building up my mileage I will limit my targeted workouts to no more than once per week. Most often the targeted workout will be a strength session in the gym. 

Aside from that, my longer runs also have a few interval-like efforts. The reason is that I live in the mountains and none of my trails are flat. Every run that I do is on an undulating trail meaning that the uphill sections require slightly more effort to get over.

The Triathlon Training-Block Method For Increasing Mileage 

Having raced triathlons, there is another trick that I’ve used to great effect when building my mileage for trail running. What I do is split my training into training blocks of 4 weeks each during a build phase above my baseline. I look at increasing my run mileage on a block-to-block basis rather than week-to-week. 

As I mentioned each block is 4 weeks in length. By way of example, if I do 30 miles in week 1, I can then increase this to 33 mi in week 2 and 36 miles in week 3. Week 4 will be my recovery week where I reduce my mileage by 50% of whatever it was in week 3, so in this case week 4 will be 18 miles. 

This will conclude the first block of training and I begin the second block on whatever I did in week two of the preceding block. In this example, I was at 33 miles in week two of the first block so I begin the second block at 33 miles for the first week 36 miles for the second, and 40 for the third. This will bring me to my second recovery week where I will again cut the mileage to 50% of whatever it was in week 3. Which in this instance will be half of 40 in other words 20 miles will be my maximum mileage during that second recovery week. 

My third training block then starts at 36 miles, which is what I was doing during week two of the second block. 

As you can see from this example even though it initially appears that I might be increasing my mileage by 10% per week or slightly more, the recovery week allows me to properly absorb the training done during the preceding three weeks.