Trail Running: Increasing Distance and Endurance

This article is part of our series: Training for Trail Running.

 A woman using a foam roller on her calves

Whether you’re registered for a trail race or simply want to run farther for exercise, working on increasing distance and endurance can be an important aspect of reaching your trail-running goals.

There are many philosophies on how to best train to increase distance and endurance. Several tried-and-true approaches include:

  • Adding mileage gradually so you don’t overdo it
  • Changing your pace to boost your training
  • Heading to the track for endurance workouts
  • Running for the hills to increase strength
  • Running doubles (two runs in a day) to prep your body for long runs
  • Doing plyometric workouts to build leg strength with box jumps, burpees and more
  • Eating and drinking well because proper nutrition and hydration are key to any training program
  • Resting to ensure your body can get the most out of each workout

Your first step, as it is with any new training program, is to consider your health and fitness level. If you have any concerns, consult your physician. After that, you can train solo, but taking some classes, joining a running club and/or finding a coach or trainer usually helps you progress faster, and it’s often more fun.

Find a Running Class or Club at REI
You can also get technique help from trail-running classes and clubs:


Add Mileage Gradually

trail runner running along the trees

If you increase mileage too abruptly you can risk injury. Most experts recommend increasing your weekly mileage by about 10–20 percent and then sticking with that amount for two weeks before bumping it up again. For example, if you’ve been running 30 miles per week for a couple weeks, you can increase that by 3–6 miles (to about 33–36 miles) and run that amount for two weeks. Then increase your new weekly total by another 10–20 percent, and so on.


Change Your Pace

trail runner looking at their fitness watch
Training at different paces is standard practice for serious runners and an effective way to work on endurance. With a basic understanding of pacing, you’ll be able to get the most out of your workouts.


Training Based on Race Pace

Experienced runners will usually train at various race paces, such as a 5K or 10K race pace. (Race pace is simply the pace at which you can run a race of a certain distance.) Race paces serve as good benchmarks in a training plan and can help you determine other paces to run at.

To figure out your race pace for a distance you’ve run, you divide your finishing time in minutes by the distance in miles. For example, if you finished a 5K in 21 minutes, you’d divide 21 minutes by 3.1 miles to get 6.77 minutes per mile (which equates to 6 minutes and 46 seconds). You can also use an online race time predictor to do the calculations for you.

Once you know your race pace, you can use that as a point of reference to determine these other training paces:


How to measure it

Slow, easy pace

About 2 minutes per mile slower than race pace

Tempo pace

25–40 seconds per mile slower than race pace


All-out pace

Sprinting pace


Training Based on Heart Rate

If you’re new to running, you can train with a heart rate monitor. For example, the pace of an easy run should be at about 60–65 percent of your maximum heart rate. To learn more, including how to calculate maximum heart rate (HRmax), read our article, Heart Rate Monitors: How to Choose and Use.

Here’s a breakdown of different types of runs and the corresponding heart rate, as well as an alternative way to estimate your heart rate:

Run type

Percent of HRmax

How to estimate it

Easy run


You can carry on a conversation

Long run


You can speak sentences

Tempo run


You can speak single words

Speed run


You can’t speak comfortably


Head to the Track

the surface of a running track
Track workouts are nothing new for runners focused on getting faster, but they’re also a useful tool for increasing distance and endurance. Doing longer tempo runs gets your body used to sustaining a certain pace over distance.
Here are some recommended track workouts for building endurance and distance:


Mile repeats: Run one mile (four laps on a standard-size track) at your 5K race pace then rest for four minutes. Repeat four times.

Repeat pace step-downs: Run four miles without stopping. Run the first mile (four laps around the track) about 20 seconds slower than your 5K race pace, and then each mile after that 10 seconds faster than the previous. Following this sequence, your final mile will be at a pace that’s 20 seconds faster than your 5K race pace.

1200m ladder: This ladder workout reduces the distance you run with each interval. Start by running 1200 meters (three laps around the track), then rest for two to three minutes. Then run 1000 meters, and rest for two to three minutes. Continue this sequence, reducing by 200 meters each time so that you run 800 meters, 600 meters, 400 meters and 200 meters.

Run the first interval a bit slower than your 5K race pace and then try to run each interval just a bit faster than the previous one.

5 x 1000 meter repeats: Run five 1000 meter laps at your 5K race pace with about a three-minute rest between each lap.


Run for the Hills

two train runners running on an uphill trail
Running hills is an excellent way to increase strength, which will pay dividends on your long-distance runs. Hill repeats, which are simply laps up and down a hill, are good for building speed and endurance. Look for a hill that has a nice steady, gradual incline rather than a sharp increase. You want to be able to maintain a consistent quick pace without maxing out your cardio. Two possible hill workouts include:
One-mile repeats: Run one mile uphill at a pace that’s about 40 to 45 seconds slower than your 5K race pace. When you reach the one-mile mark, turn around and do an easy jog back to the start. Rest for two to three minutes, then repeat. Do a total of four to six reps. If you’re training for a distance longer than about a 10K, aim for six reps.


Cut-downs: The idea of this cut-down workout is to reduce the distance of the intervals but keep the pace the same. Try to maintain a pace that is about 40 to 45 seconds slower than your 5K race pace.

  • Run uphill for one mile; jog down; rest two to three minutes; repeat
  • Run uphill for three-quarters of a mile; jog down; rest two to three minutes; repeat
  • Run uphill for a half mile; jog down; rest two to three minutes; repeat



Run Doubles

Running doubles, or two-a-days, simply means you run twice in a single day. It’s a technique used by many experienced distance runners to get their bodies ready for long-distance running.

Doubles are a good way to increase your fitness level without putting too much stress on your body. Instead of running 10 miles in a single push, you can split that up and do two shorter runs with a period of rest and recovery in between. This also makes it easier to fit long runs into a busy schedule. Some runners like to use one of the runs as a warm up for a harder run, or do a hard run with a recovery run later.



Plyometric Workouts

Plyometric workouts are essentially jump training and are often regarded as a way to improve your explosive speed. But, they’re also good for developing strength that will help you on longer, slower runs.

With all plyometric exercises (“plyos” for short), the idea is to exert your maximum effort in short intervals of time. Here are some examples of good plyos (you don’t have to do all of these. Start by choosing three or four exercises and doing them two or three times per week):

exerciser demonstrating the box jump plyometric exercise
Box jumps (quads, hamstrings, calves, glutes): Box jumps train your fast-twitch muscle fibers for quick reaction times. Squat downward and explode up while swinging your arms to leap onto a box that is about one to two feet high. Step down. Do three sets of 10 reps, with one to two minutes of rest between sets.


exerciser demonstrating the skater jump plyometric exercise
Skater jumps (quads, glutes, calves): Channel your inner speed skater to improve your strength, balance and ability to change direction. Start with your legs shoulder width apart and your knees bent. Push off with your right leg to jump to the left and land on your left foot. As you do so, your right leg will swing behind your left leg. You can touch the ground with your right hand as you’re landing on the left foot. Immediately push off with your left foot to jump to the right. Do three sets of 10 reps on each leg.


exerciser demonstrating the single-leg hop plyometric exercise
Single-leg hopping (quads, calves, ankle invertors and evertors): This exercise develops calf and quad strength while also improving your ankle strength for better balance. Stand on one foot and hop to a point about 15–20 meters away. Switch feet and hop back to the starting point. Repeat. You can also do side-to-side hops to develop greater lateral stability.


exerciser demonstrating the broad jump plyometric exercise
Broad jumps (quads, hamstrings, calves, glutes): Broad jumps are an excellent way to improve your lower-body power. Start with your legs about shoulder width apart. Swing your arms forward and up and rock onto your toes. As your arms swing back down and behind you, lower your butt and bend your knees in preparation to jump. As your arms start to move forward, explode off the ground to jump forward as far as you can. Absorb the impact of the landing by bending your knees and then go right into your next jump. Make sure you land with your knees over your feet. Your upper body can be angled forward, but keep your back straight. Do three sets of 10 jumps, with rest in between each set.


exerciser demonstrating the burpee plyometric exercise
Burpees (quads, glutes, hamstrings, calves, abs, arms, chest, triceps): Burpees are a full-body workout that will get your muscles and lungs burning. In addition to the cardio and muscle workout, they’re good for training your agility and balance. Start standing with your feet shoulder width apart and your arms at your side. In one smooth motion, squat down, place your hands down on the ground in front of you and kick your feet back so you’re in the plank position. Do a pushup so that your chest touches the ground and return to plank position. Now jump your feet in toward your hands then explode straight up to jump off the ground while reaching your hands up over your head. When you land, immediately go into another burpee. Do two sets of 10, with rest in between the sets.

Nutrition and Hydration

trail runner fueling up on the trail
Staying properly fueled while training is extremely important. If you don’t eat and drink right, you may suffer from fatigue, muscle cramps, nausea or worse, which will prevent you from reaching your distance and endurance goals. Here are some basic hydration and nutrition guidelines to follow:


  • Pre-hydrate: Drink 17–20 fl. oz. about two hours before you run so you’ll start off properly hydrated.
  • Maintain hydration: Drink about 5–10 fl. oz. (or a few good long drinks) of water every 15–20 minutes while running.
  • Eat up: For runs lasting about an hour or more, consume 200–300 calories (mostly from carbohydrates) per hour while running.

Learn more in our Hydration Basics for Trail Running article and Nutrition Basics for Trail Running article.



Rest and Recover

It’s important to allow your body time to recover after hard workouts. As a general rule, don’t do back-to-back days of hard workouts and give yourself at least one day off of running per week. Proper rest can help prevent overuse injuries, restore your energy levels and keep your motivation high.

To give your body a break from the pounding of running, try doing some light cross-training on your rest day or between hard running days.



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Contributing Experts

Julia Zuniga
Julia Zuniga

Julia Zuniga is an REI Outdoor School Instructor in San Diego, Calif. She holds a Master’s Degree in Exercise Science and her expertise is in fitness and trail running.

Matt Jewett
Matt Jewett

REI employee Matt Jewett is a former intercollegiate cross-country and track athlete and semi-elite sponsored runner. He has coached numerous runners, from top-ranked high-schoolers to coworkers to his own two daughters and their friends.