If you know anything about the Boston Marathon, you’ve probably heard of Heartbreak Hill, the punishing half-mile incline that comes over 20 miles in to the storied course. What tends to get less attention? The steady downhill of the first 17 miles of the race, which loses almost 500 feet in elevation. “Everyone dreads the hill, but a lot of runners don’t think about how to prepare for downhill running,” says Elizabeth Corkum, aka Coach Corky, a New York City-based running coach and personal trainer. “A lot of runners get to the hills and realize their quads are shot.”

That’s because your quads, or the front of your thighs, take the brunt of the load while running downhill. It can prove to be more than many runners are prepared for, and the decline can cause some runners to lose control of their form, or run faster than they are capable of sustaining.

But done correctly, running downhill can be “fast and fun” says Corkum, who recently logged her first sub-three-hour marathon at Mount Charleston, a 5,000-foot-net downhill race. Even if there are no downhill races on your calendar, you’re bound to encounter declines at some point in your running—whether you’re doing hill drills or running on trails. Use these tips from Corkum and other experts for safer, smoother downhill running.

Why running downhill is so freaking hard

Running downhill takes such a heavy toll on the legs because it involves an eccentric contraction—meaning the quadricep is lengthening as it takes the impact. It’s not something many runners train for, says Scott Frowen, CSCS, an athletic trainer for UPMC Sports Medicine. It’s why many end up finishing downhill races with much more soreness in the quads than they’re used to.

Going down a hill can also feel scary, says Kai Ng, aka Run Coach Kai, a USATF and RRCA certified running coach. This can cause runners to tense up, or adjust their form by leaning backwards. Others are tricked by how easy downhill running can feel at first and end up losing control and running too fast—which they pay for later.

How to conquer downhill running

Learn proper running form and stick to it

Even runners who practice good form on flat terrain can get thrown off by declines, says Kai—that’s why he recommends getting the basics down on flats before attempting lots of hill work. Though downhill running will require a few adjustments, overall, proper running form is proper running form, says Frowen. Don’t let hills make you forget to drive your knees, stand up tall, send your elbows back and turn your feet over quickly.

Relax and let gravity do the work

Especially when racing, many runners are tempted to “hammer it” on downhill stretches in order to bank or make up time, says Corkum. That could be a strategic choice for a short race, or the end of a race, but “that’s when you’re going to destroy the quads,” she says.

In general, Kai recommends an “easy, but not lazy” effort on downhills, staying in control of your form while allowing gravity to do the work of pulling you forward. Downhills can also be an opportunity to recover from challenging uphills, he says.

Lean slightly forward

It’s only natural to be scared that you’re going to tumble down the hill, which is why many runners lean backwards. But Frowen says this is equivalent to driving down a mountain with your foot on the brake the entire time—when you get to the bottom, your brakes, or in this case your quads, will be shot.

Leaning backwards also causes runners to heel strike, which sends impact up through the knees and hips, and risks fracturing the bottom of the foot, says Corkum. Instead, relax into the hill and lean slightly forward, catching yourself with the quick turnover of your feet, which should be landing midfoot. Support yourself with your core (runners not used to downhills may be surprised to have sore abs afterwards, says Corkum) and stand tall with your shoulders rolled back and chest open.

How far you lean will determine how fast you go—Kai suggests trying to maintain a perpendicular relationship to the incline of the hill. Sometimes runners lean too hard, he says, which causes them to lose control and go too fast, and can put too much pressure on the balls of the feet, leading to shin splints and knee pain. “The hill does not dictate how fast you go,” he says.

Know where you’re going

Kai says that he often has clients who vertically oscillate—or slightly jump up—as they run down hills. “I always say: ‘Is the finish line up there or is it in front of you?’” he says, adding that not only does this slow you down and waste energy, but it multiplies the impact of downhill running on your muscles and joints. “Understand which direction you want to go,” he says.

On the other hand, don’t look down, says Corkum, which can close off your airway. As tempting as it can be, trust that the ground will be there to meet you and look ahead.

Strength training exercises for downhills

There’s no way to improve your downhill running form without regularly incorporating downhills into your training, but start slow, suggests Kai, who recommends working with more gradual declines, like bridges, at first. Since running downhill, even when done correctly, can be so taxing on the body, Frowen says hills should only be a major part of your run two times a week at most.

Meanwhile, strength-training, always important for runners, is especially key when prepping for downhill running—Corkum recommends incorporating strength work two to three times per week. Use these exercises to build strength in the core and quads.

Plank rocks

Corkum recommends spending time in plank since it’s the same spinal position you want to be in when running, and can build core stability to support the forward lean when going downhill. Begin in a forearm plank, “making sure you’re in a good pelvic tilt,” says Corkum. Rock forward onto the tips of your toes, sending the head forward over the hands, and then backward, sending the heels back. “Learn what those muscles feel like when they’re activated,” she says. Continue moving back and forth for 30 to 60 seconds.

Forward and reverse lunges

To prepare the quads to take the load of running downhill, Corkum suggests forward and backwards lunges. Beginning in a neutral standing position, take a big step forward, creating a 90 degree angle in both knees and keeping the torso upright, then step back into your starting position. Next, step that same foot backwards, coming into a reverse lunge, both legs bent at 90 degrees, and back knee under hip. Alternate sides and stepping backwards and forward, and advance by adding a weight in each hand. Continue moving back and forth for 30 to 60 seconds, then switch sides and repeat.

Jump squats

For a higher-impact quad strengthener, try jump squats: Start standing with feet about hip-width apart, lower into a squat position, keeping your knees behind your toes and your torso upright. Push down through both feet to jump up in into the air, extending both legs to straight, and swinging straight arms back behind you. Land softly with bent knees back in your squat. Continue for 30 to 60 seconds.