Why do my knees hurt going downhill, and how do I stop it?

Going up is limited by lungs and legs; going down is limited by the knee. Descending is eccentric loading — the quadriceps lengthen under tension to control each step — and the forces through the kneecap are several times body weight, multiplied again by whatever is in your pack. That is why knees complain on the way down and not on the way up, and it is why the answers are mechanical rather than medical for most people.

Step by step

1. Shorten your stride.A long step downhill lands on a nearly straight leg with the heel out in front, and the joint takes the shock. Small, quick steps keep the knee bent and let muscle absorb the load. This is the single biggest change and it is free.
2. Land softly with a bent knee.Aim to place the foot rather than drop onto it, with the knee already flexed. Think of walking down quietly. Noise is impact.
3. Do not lean back.Leaning back puts you on your heels, which reduces grip and increases the shock. Keep your weight over your feet with a slight forward lean from the ankles, and look a few steps ahead.
4. Zig-zag on steep ground.Descending diagonally reduces the gradient you are actually walking down. On steep grass and scree it also improves grip enormously. Take the extra distance.
5. Use two poles, lengthened.Poles take a measurable share of the load off the knees on descent — enough that people with knee problems can walk when otherwise they could not. Lengthen them for downhill so your elbow is around a right angle when the tip is planted below you, and plant them ahead and to the side.
6. Lighten and settle the pack.Every kilogram in the pack multiplies through the knee on every step down. Take less, and carry what you take high and close to your back so it does not swing and shift your balance.
7. Check the boots and the lacing.Toes hitting the front of the boot on descent means the foot is sliding forward — lace with a heel lock so the heel is held back in the boot. Worn-out cushioning and a boot half a size too small both make descents much worse.
8. Build the strength that actually protects the joint.Quadriceps, glutes and calves control the knee. Step-downs, split squats, wall sits and single-leg work over a few weeks make a large difference to descent tolerance. This is the long-term answer and it works.
9. Plan routes with the descent in mind.A route that climbs a steep face and descends a long gentle ridge is far kinder than the reverse. If your knees are the limiting factor, choose the direction of travel deliberately.
10. Know when it is not just loading.Pain that is sharp rather than aching, a knee that locks, gives way, swells afterwards, or hurts at rest and at night, is not a technique problem. See a GP or a physiotherapist rather than working through it.

Tips

• If you only own one pole, use it on the downhill side on traverses and hold it in whichever hand gives most support. Two is much better than one.
• Rubber tips on poles grip well on rock and paving; take them off for soft ground and use the carbide tips.
• Do not run down scree unless you know the slope. It is fun and it is how ankles get broken on hidden boulders.
• Warm the legs up on the flat before the first steep descent of the day, and stretch the quads afterwards.

Common mistakes

• Striding out to get the descent over with — Long steps land on a straight leg and the joint takes the whole impact. Faster is not shorter if it ends the walking season.
• Carrying poles strapped to the pack on descents — That is exactly the part of the day they exist for. Take them out at the top.
• Assuming knee pain means you should stop walking — For most people the answer is more strength and better technique, not less walking. Progressive loading is what makes a knee tolerant.

If it doesn't work

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