Braking with Your Legs, Not Your Knees
We've talked about loose rock and where ankles go wrong. This lesson is about the part right below that. Not where your foot lands, but what your leg does when it lands.
Most people brake with their knees on a downhill and don't know it. Every step becomes a small catch, a locking of the joint to stop your body from pitching forward. Do that for two miles of descent and your knees are doing the work your whole leg should be sharing. That's how people end a hike fine and wake up the next morning unable to get down their own stairs.
What braking with your knees looks like
Stiff-legged steps. Heel strikes hard and straight down. Knee locks out at the bottom of each step to stop the momentum. It feels controlled in the moment because you're not falling, but you're transferring all that braking force into one joint that wasn't built to be a brake pad.
What braking with your legs looks like instead
You want your whole leg soft through the step, not just your foot finding a place to land. Knee stays a little bent through the strike, absorbing the shock the way a shock absorber does, not the way a stick does. Your glutes and hamstrings do more of the decelerating. Your knee just goes along for the ride instead of stopping the ride.
Here's how I actually do it, and I do this slowly and out loud when I'm walking with people, because it's a habit you build by feeling it, not by hearing about it once.
Shorten your stride going down. Same as the climb, but for a different reason. A long stride downhill means your leading foot lands out in front of you, which means your knee has to lock to catch your weight. A short stride keeps your foot landing closer under your hips, where your leg has room to bend and absorb.
Bend the knee through the landing. Don't try to land soft and then straighten up. Let the knee stay bent as your weight comes onto that leg, and let it straighten again as you push off. Think of it more like a spring compressing than a peg hitting the ground.
Let your glutes and hamstrings take the load, not your quads and knees. You'll feel this in your back leg more than your front one if you're doing it right. Your legs should feel worked at the end of a downhill. Your knees shouldn't feel it at all.
Slow your pace on the steep sections specifically. Not the whole trail. Just the parts where the grade actually asks something of you. I'd rather you take an extra four minutes on a steep quarter mile than fly down it and pay for it in your knees for a week.
A plain opinion
Uphill builds you. Downhill breaks you. I've said this before in this course and I'll keep saying it because most people have it backwards in their heads. They brace for the climb and relax on the way down, and the descent is exactly where the damage happens. Treat the downhill with the same attention you gave the uphill. More, honestly.
About the watch
I tried a fitness watch for about a month, mostly to see what my heart rate was doing on climbs and descents. Gave it up. Not because it didn't work, it worked fine, but because I noticed I was looking at my wrist more than I was looking at the trail. On a downhill with loose rock and roots and drop-offs, that's exactly the wrong place for your eyes to be. I went back to just counting my own breathing and paying attention to how my legs feel. If a watch helps you and you can keep your eyes where they belong, use one. I just can't.
A home exercise, no trail required
You can practice the knee-bend habit in your own house. Find a set of stairs. Walk down them slowly, and pay attention to whether your knee locks straight at the bottom of each step or stays soft. Most people find they've been locking it their whole lives and never noticed until they went looking. Do this for a week, a few minutes a day, and you'll start to feel the difference between a leg that's absorbing and a leg that's just stopping.
Before next time
Next time you're on a downhill, even a short one in your neighborhood, try shortening your stride and keeping a bend in your knee the whole way through the step. See if you notice a difference in how your knees feel that evening.