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Training Plan for your First Trail Half Marathon

Trail running can be a respite from staring at the white line on the side of the road. Variances in surface, small obstacles such as roots and rocks, and frequent elevation changes provide you with ample distractions that seem to make the run go by faster. If you’ve run a few 10ks and have been thinking about trying a half marathon, why not take your training a step further and try a half marathon trail run?

Tips for Trails

Fuel, Hydrate, Recover

Race Day

Training Plan

At the bottom of this article, the accompanying 12-week trail half marathon training plan is designed for runners who have run, at a minimum, a few 10ks and are comfortable with some base mileage. It’s designed to alternate hard efforts with easy runs or cross training on weekdays with back-to-back longer runs on the weekends. The order of training sessions is more important than the day they occur, so if Friday and Saturday are your weekend, shift the plan accordingly. Active recovery days are ‘rest days.’ ‘Active’ simply means that you should engage in some light movement during the day—and can be as light as a meditation class—because anything is more beneficial than sitting on the couch.

Where indicated, use your current 5k and 10k race results as pace goals for your trail running workouts. Avoid using a faster ‘dream goal’ pace, as you’ll be forced into an anaerobic zone to complete the trail running workout plan. Yes, you might get faster, but you won’t gain the endurance necessary to complete your half marathon.

We’re not all Dean Karnazes, and not everyone’s body is suited for an Ultramarathon. Listen to your body and stay safe while pushing your limits.

Tips for Trail Running

If you haven’t previously dabbled in trail running, here are a few tips and tricks that will keep you on your feet while you’re knocking out your trail running workout plan.

Look Up
Not at the sky, but at the trail a few feet in front of you. Avoid zoning out, as this may lead to spread-eagle landings when you trip over rocks. To accomplish this, spend as much time on the trails as possible. Every workout except track intervals may be done on trails that have relatively consistent elevation changes.

Avoid Drastic Courses
Running uphill for four miles and then back down for four more defeats the purpose of an eight-mile negative split run. Your trail running training plan should avoid these extreme elevation changes.

Vary Your Stride to Match the Terrain
Practice changing up stride length during your fartlek intervals or your tempo run.

Loosen Up
Let gravity help you run downhill. Don’t lean back and brake using your heels; rather, lean slightly forward and take quick footsteps, minimizing the time your feet are in contact with the ground.


Fuel, Hydrate, Recover

To maximize training results, I like to think of every workout as a microcosm involving fueling, the exercise itself, and recovery.


Running a half marathon is primarily an aerobic endeavor, with a few forays into anaerobic as you punch it uphill or try to pass a runner in front of you. The aerobic energy system mostly uses a combination of carbohydrates and fat, the proportion of which depends on the intensity of the exercise. For very low-intensity exercise, your muscles mainly draw their energy from fat. But as your effort level goes up and your muscles have to generate energy more quickly, the proportion of energy from carbohydrates increases.

Now, this doesn’t mean that you’re instantly using that bagel you snuck for breakfast. The carbohydrates used during aerobic activity are converted to and stored as glycogen. These stores are limited, and as they begin to run out, the proportion of energy provided by fat increases again as the body tries to limit the loss of glycogen. Once your glycogen stores have run out, your body begins to break down muscle proteins to provide energy and to maintain blood-sugar levels. While burning fat is a usual goal of endurance runners, especially new runners, the breakdown of muscle proteins is not.

Eat and drink before heading out for each leg of your trail race training plan. A small snack will help keep blood-sugar levels consistent. A 150-calorie, carbohydrate-rich snack (with a trace amount of protein) eaten 15-30 minutes before your run should suffice. Avoid the thought that to lose weight you shouldn’t eat.

During a run, the average person is able to process between 30 to 60 grams of carbs per hour. Taking in more does not make you faster, nor will it help minimize glycogen depletion. At worst, you may end up with gastrointestinal issues.

Gels have become a common during-race fuel. They are compact to carry and contain about enough carbs to ingest one per hour. If you eat small meals throughout the day, you will not need to fuel during easy or shorter runs. Ingesting a gel during harder efforts and longer runs will help reduce the possibility of hitting the wall. This ‘bonk,’ as it is referred to, occurs when your glycogen stores are depleted.


Race directors are realizing that events with thousands of runners have a high environmental impact. Thousands of cups, gels, and assorted wrappers are used and thrown away. To this end, several races are becoming “zero impact.” This means you’re required to carry a water container. While some participants prefer to use a simple water bottle that they refill at aid stations, a hydration pack is another option. The nice thing about a pack is that you are able to carry the drink mix you’re used to training with for the entire run. My personal pack of choice is the Salomon S-Lab Hydration Pack. Often, there’s the temptation to use whatever is on the course, which is perfectly acceptable if you’ve trained with it before.

Now, just how much should you drink? In general, you will sweat 1 to 1.5 quarts per hour of exercise. And the adage is true: If you’re thirsty, you’re already becoming dehydrated. Most runners will find that 6-8 ounces every 15 minutes is adequate. While new runners often think that water is sufficient, if you guzzle cup after cup without adding salt or any electrolytes, you are at risk for hyponatremia. While rare, this condition can lead to organ failure. A much less drastic, and more likely, result is that you suffer muscle cramps, headache, or nausea after several hours of exercise, especially in hot weather. Why? You need sodium to contract your muscles.

You’ve heard the phrase, “It’s all mental?” Well, the stimulus to move a muscle (in this case. to run) begins from the brain and travels via neurons to muscles. This stimulus causes an action potential in the neuron before it hits the muscles. The action potential can only be generated with sodium and potassium ions. Without the initial action potential there is no muscle contraction.

Some runners use tablets such as NUUN dissolved into their drinks, which contain sodium, potassium, and other electrolytes, when they are working on their backcountry trails program.  Other runners use electrolyte capsules taken with water, such as Hammer Nutrition Endurolytes. A third option is to use a drink such as Clifbar Clifshot Hydration that combines your carbohydrate needs with electrolyte replenishment. At 20 grams of carbs per serving with sodium and potassium, it’s an excellent all-in-one drink. One thing to note is that if you want to split your nutrition between gels and drink, make sure you sip water with your gel, not drink mix.


As distance runners, we strain to go faster and longer, and in the process, we not only deplete fuel sources but cause microscopic tears to our muscle tissue. The damage is quickly assessed by our bodies, which open stores for refueling and send white blood cells to repair muscle tears. In fact, it isn’t the training itself that makes us faster or stronger—it’s the recovery time between training. For this reason, it’s important to continue to hydrate post run. Additionally, you’ll want to consume a drink that has a 4:1 ratio of carbohydrate to protein.

Ideally, you want the drink to also contain sodium, calcium, magnesium, zinc, potassium, and branch-chain amino acids. In reality, very few recovery drinks contain all of these. The Louis Garneau LG1 Recovery Drink has everything but zinc and comes in punch, lime and orange to help temper a post-run sweet tooth. A few hours after running, refuel with a balanced meal.

In addition to refueling, keep your muscles warm by changing into dry clothes. Use your body’s metabolic activity to aid the recovery process and perform dynamic stretches while your legs are still loose. If you find your legs to be swollen slightly, rather than using ibuprofen, which can provide a false sense of recovery, elevate your legs, take an ice bath, or practice light self-massage to help the body flush out generalized inflammation. Localized inflammation, however, is often a part of the repair process and should not be thwarted. The body is a lot smarter than we often give it credit for.

How to Prepare for Race Day

The Night Before

The night before a race, it’s often hard to sleep. Your mind keeps going over whether you followed your trail run training guide well enough and the challenges you’ll face on the race course. To compensate for this restlessness, I encourage my athletes to make sure that two nights before race day, they get more than adequate sleep. Make sure all of your gear is laid out and ready to go so you won’t be stressed in the morning. Get to the race course early and get in 15-20 minutes of easy running with a few fartlek intervals of 20 seconds. Position yourself at the start and continue to stretch and hydrate.


Pre-Race Fuel

I’m sure you’ve heard of carbo-loading. While many athletes still swear by the process, if you eat a balanced diet with adequate carbs, it is not necessary for a backcountry half marathon. It’s more important to be consistently fueled. On race day, set the alarm early enough to eat a carbohydrate-rich meal and digest it before your race begins. It should also include protein and some fat. My personal favorite is a peanut-butter-and-banana sandwich with a small amount of honey. It never fails me. It’s what I eat to this day before a long day of running or even skiing. Be sure that you give your body enough time to digest (in other words, use the john before you race). If you don’t, you may end up doubled over with cramps.


Race-Day Pace

When the gun goes off, don’t let adrenaline take over and try to run your fastest mile ever. If you do, it may be the only mile you run. The 12-week program includes negative split runs, and this is the mindset you should be in at the start. Your run should start out at just below your half-marathon goal pace and gradually increase to goal pace. Note that as the elevation changes, so will your pace, so if you’re wearing a GPS, look at the average speed. The plan includes plenty of 5k pace intervals so that you’ll hit your goal time without having to run like a gazelle in the last mile to make up time.

Have fun, and don’t forget: recovery on race day is as important as on any other day. Drink your 4:1 recovery mix, then go for the pizza and beer.

12-Week Training Plan for Trail Half Marathon

Download the Plan

Now that you’re ready to start training, check out these upcoming trail half marathons:


And if you need training tips or advice on choosing your next race, reach out to one of our Gearheads for help.