Hawaii’s hilly terrain destroyed our flat-land-conditioned legs back in January. So, with the mountains looming again in our near future, we set out to prepare our bodies for the challenge, and asked our friend and smart-as-fuck physiotherapist, Justin Vanderleest for the 411. Here’s what he prescribed:

First off, why is running even a gradually sloped hill so damn hard on the body?

Running is quite an economical motion on the flats. Our bodies are built for it. With optimal form, it’s really just the act of controlled falling forward. Gravity works in your favour on flat terrain. As you tilt forward (from the ankles, never from the waist), you begin to fall forward. Placing one foot in front of the other prevents you from falling on your face and keeps you moving forward. So, gravity can do a lot of the work to propel you along. When you’re running up hills, the same mechanics apply, but you have to do a lot of work to overcome gravity as you ascend. It’s physics.

What can we do to prepare our bodies for running hilly terrain?

I wouldn’t recommend hill training for someone who is just beginning a running routine. Start by building up your running endurance on flatter terrain. A good rule of thumb for mileage progression is 10% per week. Everyone has different mileage goals. Some college track athletes will run upwards of 160km per week. Recreational runners might be happy with a couple 5km runs per week. Either way, get comfortable with your goal mileage and incremental progressions before adding hills. A well-rounded running routine should include some strength training and stretching too. When you do add hills, cut back your mileage a bit and start small. Gradually sloping inclines will add a new dimension to your training. If you want to add steeper inclines to prepare for a hilly race, don’t be afraid to power walk the steep stuff at first. Your calves and quadriceps are going to feel it, so plan a rest day and let your body recover fully before the next run.

Would you implement a certain kind of workout into a person’s preexisting exercise routine?

Runners tend to get very tight. Regular stretching can make a big difference. If you don’t have a lot of time, the hip flexors and quadriceps–specifically rectus femoris are key. Stretching the calf muscles a few times per week will really pay off too. Runners also tend to get pretty slender. If you’re not working on strength training, your body literally uses your existing muscle as fuel during workouts. If you’re the kind of person who can’t get motivated to stretch and do some extra strength training, try finding a yoga class you like. An hour of yoga once per week can help a runner stay flexible and strong.

If you live somewhere flat, what can you do to mimic running up a hill?

I’m from Saskatchewan, so I can attest to the fact that no matter where you live, you can find hills for training. If you’re running a race with hilly terrain, there will be no substitute for the real thing. But, strength training for endurance would be a good start. Whether it’s high repetition body weight squats and lunges, a stair climber machine, or a spin class, do something to increase the resistance to motion. If none of those are available, run harder or do some sprints on flat terrain.

Any other advice for hill running prep?

Train for the descent, too. When going down hills, people tend to put on the brakes a little too much. But, this is your chance to get a free push with gravity on your side again. To keep control, try increasing your cadence, keeping your steps small and quick. Avoid the tendency to lean back and land on your heels. This will save your quadriceps and shin muscles on the descents.

On ascents, try exaggerating your arm motion pumping forward and back, and think about driving your knees forward. This will help drive you up the hill, improving your technique and discouraging the tendency to shuffle along as fatigue sets in. Hills are hard on the Achilles and knees, so make sure you have good mechanics, and don’t over train. You won’t fare well if you start running hills everyday.

Start slowly and get lots of rest. Depending on the size and incline of the hill, a hill session once every week or two might be plenty to start.

Justin Vanderleest is a super star Toronto-based physiotherapist with a focus on sports rehabilitation and injury prevention. Justin also writes for the Globe, and owns the world’s cutest dog.