When constructing a trail runner, the goal is to build up in a way that prevents breakdown. It helps to think of your running training like building a house. You start at the foundation. Yet far too often, trail runners skip this essential step, and they are left thinking that injuries and burnout are common, rather than preventable.

The Foundation—Aerobic Development

The foundation of trail running is aerobic development from consistent, easy miles. Aerobic running is lower intensity, meaning the muscles have enough oxygen to perform using aerobic metabolism. Primarily, aerobic running burns fat, rather than carbohydrates, allowing the body to become more efficient with this readily available fuel source. At aerobic paces, you should be able to hold a conversation.

The benefits of aerobic running are threefold:
• First, it improves how efficiently your body pumps blood and oxygenates working muscles, which will make you faster at all effort levels.
• Second, it builds strength in muscles, tendons and bones. That strength is essential for preventing overuse injuries.
• Third, it is fun and sustainable—since it shouldn’t ever hurt, it’s easier to stay on target and train consistently.

The Cement—Running Economy

While the foundation is built with aerobic running, it is held together with running economy. Running economy is the amount of energy it takes to run a given pace—good running economy means you don’t have to work hard to hold faster efforts. One of the main goals of running training is to improve running economy to the point that fast running feels effortless.

Consistent aerobic running with good form is the main way to improve running economy. The other way to improve running economy is by incorporating fast strides into normal runs. These efforts—between 15 and 30 seconds, on a hill or flat—are low-risk, high-reward. They build strength and aerobic capacity, with the added benefit of teaching your body that fast doesn’t need to be hard. Add short, fast strides to consistent aerobic running and you can learn to train, not strain. In the process, you can get fast without really even trying that hard.

The Frame—Resilience

Resilience over a specified distance relates to the specific demands of trail running—often, trail runners are playing like kids on mud and mountains. The upside of playing like a kid is that it mixes up movement patterns, which reduces injury risk.

The downside is that the unique stresses of trails ask more of your body’s musculo-skeletal system—more athleticism, more strength and more ability to use multiple movement patterns over an extended time. You build resilience by running hills, running long and doing workouts. Think of resilience as the frame, providing structure and stability to your house.

The Walls—Endurance

Endurance is the ability to run for an extended time, like resilience, but related to your aerobic capacity rather than your musculo-skeletal durability and strength. Consistency will get you most of the way, but you still need to run long and practice running at aerobic threshold—an effort that is not purely conversational, but not hard either.

Think of endurance as the walls of your house—you can’t last on endurance alone, but you also can’t last long without it. Thus, with these elements, your fitness house is mostly complete, with a foundation, beams and walls. You could live in it, but it’s not perfect.

The Additions—Lactate Threshold and VO2 Max

That is where hard workouts involving lactate threshold and VO2 Max come in. Lactate threshold is the effort that you can sustain for an hour—think talking in clipped sentences, and feeling a bit of a burn in your legs if you hold it for longer than a few minutes.

VO2 Max is an effort you can hold for around 10 minutes (it varies by individual)—think a respiration rate where you can’t say more than a word or two at a time. Both of these workouts can lead to big fitness gains, but they come with higher injury risk. With this huffing and puffing, it is essential not to blow the house down.

Hard workouts involving lactate threshold and VO2 Max are the fancy elements of the house—the marble staircases, opulent additions and in-ground swimming pools. You can live without them, but they can take your training “house” to a whole new level.


If you are starting from scratch, you’ll be thinking about your foundation for an extended time. Each season, as you progress, you’ll start with the foundation, before moving up to the rest of the house. By going through the cycle each season—aerobic development and running economy, followed by endurance and resilience, followed by workouts—you’ll build higher and higher, turning a single brick into a big neighborhood that you can be proud of.

But we are getting ahead of ourselves. First, we need to delve into what it means to build a base to support an outstanding trail runner.

Laying the Foundation

At its simplest, trail running training is all about running the most miles you can sustain while staying healthy, happy and motivated. Laying a rock-solid foundation is what lets you reach great heights.

Miles make the woman or man, because mileage induces running-specific aerobic development and strengthens the musculo-skeletal system. Think of aerobic running training as a nearly endless positive feedback loop. Stronger muscles and joints let you run more miles, which improves the aerobic system, which lets you run faster and longer, which strengthens muscles and joints more. There is really no stopping this merry go round of progression other than genetic limitations (which take many years to discover) or injuries.

Principles of Building the Base

How you build your base depends on your background and goals. The idea is to start safely, focusing on short, relatively slow and sustainable runs. Emphasize frequency, rather than volume—three 20-minute runs over three days is better than one 60-minute run and two rest days. This frequency phenomenon is because running is weight bearing, unlike sports like cycling or swimming. Because it is weight bearing, you are more susceptible to injuries and the body needs to adapt to the stress. Bending, and not breaking, over and over again, is the primary goal of trail training.

If you are starting from scratch, do a short run every other day. Even 10 minutes counts, and it can be at walking pace—just use running form. The goal is to build durability, not to build speed.

Over time (or if you are a more advanced runner to start) progress to running almost every day—ideally you will run five or six days a week almost year round. Some of those runs can be short—10 minutes still counts when you are advanced—but the general goal is to spread out training volume so your body adapts and thrives off of consistent daily running.

Determining Total Running Volume

Now, the million-dollar question: how much should you run? As a trail runner, you should think of it in terms of time, not distance, since different types of trails of the same distance can involve lots more or less running. Total steps are pretty consistent over time, not distance, so time is the best quantification of total stress.

At first, you might just start with 30 minutes or an hour each week spread out over three or four runs. From there, a good first milestone is five hours a week spread out over five runs, with two days off. After you can sustain that without lower energy levels or lingering injuries, you can bump it up to seven to 10 hours over five or six runs, which is the sweet spot for most trail runners during the base period. If you are really advanced, you can aim for 10 to 14 hours over six (or more) runs, but such high volumes are best pursued at the direction of a coach.

Principles of Building Running Economy

Once you reach the five-hour milestone, congratulations! You are on your way to trail-running breakthroughs. That is the time to add short strides to improve running economy, muscle strength and durability.

There are two types of strides to think about: hill strides and flat strides. As your introduction to faster running, start with hill strides, which have less pounding on your muscles and joints. Find a gradual hill between four- and eight-percent gradient, and after a 15-minute warm-up, run 20 to 30 seconds moderately hard up the hill. While you are running, focus on smooth and sustainable form—in other words, use long-distance running form, and not sprinting form. Jog down easily for recovery, and repeat four to eight times two or three times per week.

After your body adapts to hill strides over a few weeks, add flat-ground strides, which involve slightly more stress on your muscles and joints due to increased impact forces, but also involve greater economy gains due to the faster pace. Use a similar protocol, aiming to hold the fastest speed you can without straining for 20 or 30 seconds, with one to two minutes easy running to recover between each. Do these strides one day a week at first, and eventually replace hill strides altogether with flat strides two or three times per week.

While the strides are an element of the foundation, it is important that you do them year-round. Speed can be learned, and it can also be forgotten. By doing strides in the context of your normal easy runs, you can constantly reinforce running economy. Better running economy leads to better running at all effort levels, from easy aerobic running to hard workouts and even races. In that way, aerobic development plus fast strides form the basic building blocks necessary to reach your running potential.

Length of Foundation Period

This foundational period can last as long as you’d like—most of your fitness development comes from this phase, so it’s OK to linger. If you are just starting running, do six months to a year of building up your base. If you are a normal runner starting a new season or trying a new approach, spend two or three months in this phase, ideally reaching higher training volumes than you ever have before. If you are advanced, you may only need a month rebuilding the foundation. In general, you are ready to move to the next training phase when you feel strong at the highest volume you plan to sustain all season long.

Develop Trail-Specific Endurance and Resilience

With a solid foundation, you already have most of what you need to reach your trail-running potential. Now, it’s about refining your strengths to endure faster and longer efforts on epic terrain.

Principles of Building Endurance

Start with endurance—the ability to go longer and stronger at aerobic efforts. In the last third of your foundation period, you can add long runs, where you get 20-to-50 percent of your weekly mileage from a single run. Keep them easy at first, and be sure to get adequate recovery before and after the run. The idea is to train now so you can train harder later, not to train to race. So don’t be racing these long runs yet.

Once you are confident in your long runs and you are moving on from the foundation period, it’s time to work your aerobic threshold, which is slightly more intense than purely aerobic running, but with less injury risk than workouts. A couple of times each week, replace your normal easy run with an easy-moderate run, where you can still complete sentences but wouldn’t be able to rap an entire verse. This aerobic threshold running should feel like something you could sustain for a couple hours at least. Have most of your long runs end at this effort.

How Endurance and Resilience Work Together

Aerobic-threshold running over variable terrain works both resilience and endurance, since your body is adapting to uphills and downhills at a moderate, but not hard pace. Design these runs so that they involve every type of running you enjoy—especially steep downs and ups once you get more used to them. Your musculo-skeletal system will adapt over the course of a few months if you are newer to trail running, and a few weeks if you are more advanced.

Once you are really cranking in training and have not had any injury scares, you can even end other runs at aerobic threshold. Basically, the idea is to let your body flow, starting runs easy and slow and finishing faster if you feel great. However, never force it—the magic of a smart progression from a big foundation to the endurance and resilience phase is that your body starts to feel good most days, but if you try to force the issue, you might stall your fitness gains. The perfect aerobic threshold running feels like you are riding a bike downhill—mostly effortless, exhilarating and quick.

Length of Endurance and Resilience Phase

At this point, your training will involve sustained high volume, fast strides two or three times per week, and at least two runs where you end at aerobic threshold on variable terrain, including your long run.

In an unstructured way, you can add even faster uphills and downhills, starting to prepare for the hard workouts to come. And low-priority races are even OK, as long as you know that your training house is not fully constructed quite yet. Generally, you should stay in this phase as long as you enjoy it—from a month or two to most of the season. Most fitness gains come from aerobic threshold running and high training volume. But to put on the finishing touches, you have to do more structured workouts.


What Does It Mean to Do a Long Run?

It depends on how much you are running to begin with. In general, if you run less than 25 miles per week, it is any run longer than 10 miles; between 25 and 40 miles, any run longer than 12 miles; between 40 and 60 miles, any run longer than 14 miles; and above 60 miles, it’s any run longer than 16 (scaling up to 18 or 20 for people nearing triple-digit mileage).

Do Workouts and Get Race Ready

Now that you have the foundation, the frame and the walls, you can start having some fun with the design. Workouts are what turn an ordinary house into something spectacular.

Basic Workout Principles

To the mix of easy runs, a long run and strides, add one workout a week at first, and work up to two if you are advanced (with the second falling during the long run). Workouts come in all shapes and sizes, but at their core, they all involve sustaining moderate to hard efforts multiple times (or just once if you are doing a fast tempo run, sustained long run or race).

They improve running economy and aerobic fitness, like other types of running, with the added benefit of kicking your lactate threshold and VO2 Max into high gear. These higher-intensity energy systems allow your body to push harder, faster and longer—as long as you don’t get injured from the increased demands on your musculo-skeletal system or burnt out from the increased mental energy it takes to make it hurt a little bit.

Short Intervals

Start with short and simple intervals before building to longer and more complex efforts. The shorter focus at first is because you want to run all of these intervals with proper running mechanics. In shorter intervals, you can focus on staying smooth and effortless, since they are just an extension of the strides you have been doing for weeks or months.

For most athletes, 10 x 1-minute fast with 1-minute easy recovery is a great place to start, with intervals on any type of terrain (if you want to get faster, run them on flat or rolling trails; if you want to get stronger, run them on uphills and downhills). The next week, increase the number of intervals, before lengthening them to two minutes the next week, and three minutes the next.

You are ready to move on from the short, fast intervals when you reach 30 minutes of total fast sections—completing a workout like 10 x 3 minutes and feeling smooth and comfortable. All of these short intervals primarily work VO2 Max, but with some lactate threshold thrown in. Your running economy will likely skyrocket as you start adding the harder workouts—it’s not uncommon for major breakthroughs to take place in the first few weeks of workouts.

Longer Intervals

As your body adapts, you can add longer, lower-intensity intervals, like 6 x 5 minutes with 3-minutes recovery, 3 x 10 minutes with 5-minutes recovery or even longer tempos between 20 minutes and an hour in length. If you are adding a second workout to the week, you can incorporate these workouts into your long run as well. Your total weekly running volume can drop slightly, but don’t let it drop much. While workouts are great for short-term breakthroughs, long-term success is founded on sustained training volume.

Trail-Specific Workout Concepts

But what about the track and pace-based intervals? While that stuff might be helpful at the margins, it is not necessary to be the best trail runner you can be and it could increase injury risk. The track is the hamster wheel of running training, with monotonous motions. Monotony is boring and constant left (or right) turns can increase exposure to overuse injuries. Pace similarly is not important for trail training—since trail races are all different types of terrain, focusing on pace numbers is not necessary. Plus, the incessant judgment of a watch adds unneeded stress.

Instead, focus on effort. Short intervals should be moderately hard at aerobic capacity, breathing hard near the peak of your respiration rate. Long intervals should be moderate, where you can say a sentence or two, but would prefer to be silent. Trail-running training is an art, so don’t try to make it a boring, counter-productive science.

Length of Workout Phase

There is no perfect recipe for how long the workout phase should be. Ideally, it’ll be about the same amount of time you spent building your endurance and resilience. So if you spent two months after the base period doing aerobic threshold work, spend two months doing workouts. However, this is the one phase where it is not OK to linger. Err on the side of fewer workouts, not more, since workouts are the riskiest part of training in terms of injuries and burn out.

Putting It All Together

The final piece of the training puzzle is preparing for the specific demands of whatever you are training for. All of your trail-running fitness starts in the same place—aerobic development, economy, endurance and resilience—but where you take it from there is a Choose Your Own Adventure, with dozens of options.

Principles of Specificity

Break down the components of your goal events, focusing mostly on elevation gain and loss, terrain and distance. If the run has lots of up and down, be sure to mimic that as much as possible in training. If it’s an ultramarathon, be sure to focus on substantial long runs at aerobic threshold, or including workouts within the long run.

The place to alter training for specificity is within the weekly workout and long run. Decide what you will be doing based on the demands of the race. The rest of your training can remain the same as long as the workouts are specific to your goals.

General to Specific

Thus, training starts general and moves toward specific. Like a big pyramid, the general phase is bigger, and the specific phase is shorter and smaller. The length of time in each varies based on the individual. Generally, ultramarathons require more base and focused long runs, while shorter and faster races require more workouts and specificity.

Down Weeks

Throughout the training cycles, every three or four weeks, add a down week where you cut everything by 15-to-50 percent, with higher-volume runners cutting out more and lower-volume runners cutting out less. These down weeks will ensure your body adapts to the training and will allow minor injuries to heal before they become anything serious.

Pre-Race Taper Guidelines

Finally, a couple weeks before your goal event, it is time to taper. If you have been training correctly all along, you should not need too much of a cut down in training volume or intensity to be ready to race since you have avoided overtraining. Generally, you can cut down 20-to-35 percent from baseline the first week, then 40-to-50 percent from baseline the second. Keep the intensity in the program, just cut the volume of the intensity a similar amount—this will prevent the dreaded stale-legs feeling during the taper.

Standing the Test of Time

And, most importantly, know that there is no one formula that is necessary to achieve your trail-running potential. Picasso and Monet are both amazing painters with staggeringly different approaches; so too can you take a different approach to structuring your training.

That being said, there is one principle that applies across all of running training. No matter what, start with the foundation of aerobic development and build your running economy. From that base, you may want to build a mansion, or you may be content with a one-story ranch house. Start at the bottom with easy miles, build up methodically by increasing volume and adding strides, and whatever trail-running fitness you construct on top of that base is going to stand the test of time.