How to Train for a Half Marathon on Trails

Your 10-Week Trail Half Marathon Training Plan |

Completing a trail half marathon is an achievable goal for almost anyone, with a little bit of structured training. Below you will find strategies and a sample training plan for runners hoping to put in their first 13-miler (give or take a bit) on trail. The goal for athletes shouldn’t be just to finish the race—but to have fun throughout the entire process, from day one of training all the way through to the finish line.

Training Principles

Whether you’re running on a trail or a road, the same basic training principles apply. To progress over the long term, reach your full potential, and stay injury-free, you must first build your aerobic base, then develop your ability to maintain a faster pace for a longer duration, and only then, if you wish to optimize your performance, do you dive into high-intensity training. In practice, this is simpler than it sounds.

1. Run Often

The ultimate paradox of running is that you can get faster over time by running slowly. Professionals and recreationists alike should spend the bulk of their training at an easy pace to bolster their aerobic capacity. Easy runs strengthen the musculoskeletal system, stimulate growth in the circulatory system to better supply oxygen and fuel to muscles, and increase the ratio of slow-twitch-to-fast-twitch muscle fibers for endurance, among other adaptations. With a solid aerobic base, you can begin to handle harder workouts.

If you’re new to distance running, or fresh off the couch from a running hiatus, start with short runs, anywhere from one to three miles, and try to build up to four or five runs per week. For the time-crunched athlete, or those who are just starting out, your runs can be as short as ten minutes, or you can alternate between running and walking as needed. What’s important is that you get out regularly.

Easy running is defined by perceived exertion—how you feel in the moment—and not speed. An easy pace means that you can hold a conversation. If you’re on trails, at first that might mean running the flats and walking the hills. If you need to recover from the run, it wasn’t an easy day.

Pro tip: ditch the GPS watch. Removing metrics of evaluation from your running life is the best thing you can do for your long-term mental health and physical progress. Easy is as easy feels, not what the watch says. The body and brain don’t respond to numbers, they respond to stress.

Ideally, you want to slightly increase your training volume every week—around one to four miles—with the occasional reduced week for recovery. If this is your first half marathon, try to reach at least ten miles on trail as a minimum for your longest training run, and make eight-mile runs routine. Taper off two weeks before the race by reducing your overall running volume by 10 to 30 percent while maintaining the same volume of intensity, such as speed work.

2. Run Fast

Introducing speed work will help improve your running economy and overall pace for the same level of perceived exertion. As you improve your speed, your easy runs will feel just as easy, but you’ll be going faster without realizing it. Speed work doesn’t replace easy runs but should be mixed in one to three times per week, usually during the second half of a run.

A go-to speed workout involves strides, short bursts of fast running (usually 15 to 30 seconds) with easy running in between (one to two minutes) for close to a full recovery. These are done in back-to-back sets and might look like: twenty seconds fast, two minutes easy, twenty seconds fast, two minutes easy, and so on for four or more sets. For the fast portion, you want to run at the fastest pace you can sustain for two to four minutes, or roughly 80 to 90 percent of your maximum speed. Once you can run 15 miles total in one week, you can mix in strides two to three times per week.

When you’re starting out, do strides uphill (ideally on a consistent 6 to 8 percent grade), because this reduces the impact forces on your joints and bones. As your body adapts to the stresses, you can progress to doing strides on flats, which is better for speed training.

This forms a positive feedback loop with aerobic development. As you introduce strides, your easy miles will get a little faster, so your aerobic system develops even more, which then lets you run even stronger on the strides.

3. Run Everywhere

Strive for a balance between road and trail running in training. Trail running involves biomechanical strains that road running does not—you’re running up and down hills, stepping over roots and rocks, and dealing with uneven footing. Trail running is also slower and less efficient than road running. Every time you adjust your stride for an obstacle or turn, your power output and pace drops.

During the week, when schedules are busy, run roads, dirt paths, and whatever’s convenient, but on the weekends, make your runs an event. Do all of your long runs on trails that are close as possible to what you’re going to be racing on.

If your race is on a hilly course, focus your trail days on running the downhills efficiently. The uphills might feel harder, but when you run downhill, your calves and quads act as shock absorbers and are subject to higher levels of strain. “Uphills are just a byproduct of aerobic fitness and speed. The faster you are, the better you’re going to be at climbing,” says Roche. But downhills involve eccentric loading—when muscles elongate under a load rather than contract. That’s where muscle damage happens. If you’re not prepared for downhills, your legs are going to be a puddle of Jell-O after the first hill on race day.

4. Run for Fun

Draft a training plan (request sample schedule below), and try to stick to it, but don’t get stressed if you fall short of your mileage goals or miss a day here and there. Work, life, and kids can often get in the way of a systematic training plan. Do what you can when you can, especially if you’re busy. If you miss a day, you can try to make it up later if you feel refreshed enough, but it’s often better to skip the day and continue on with the plan. If you miss two or more days in a given week, repeat the week.

Getting too focused on the day-to-day mechanics of your training plan often adds another stress that makes the training less effective anyway. The body doesn’t adapt in states of chronic, high stress, and it doesn’t differentiate between the source of stress—whether that’s running or parenting or work or anything else. If you feel fatigued for more than one or two days in a row, then we need to change the approach. We need to back off.

So take the pressure off, and remember—you’re doing this because it’s fun. Race day should not be an event to fear but a day to celebrate your hard work.

The Ten-Week Training Plan

For a healthy individual who can run four miles in an hour, ten weeks is a reasonable time frame to prepare for a trail half marathon, and six weeks should be the minimum. Off the couch, you might want to add a few extra weeks to ease back into the rhythm and allow your musculoskeletal system to adapt to the impacts of running. If you’re trying to optimize performance and crush a race, an ideal length of time to train is closer to three or four months.

Everyone is different, and there’s no such thing as a one-size-fits-all training plan. Send us an email for a sample training schedule: SEND ME THE 10-WEEK HALF MARATHON TRAINING PLAN


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