Have you ever lost balance on a steep downhill walk, and ended painfully on your bottom? If so, then you can guess what this text is about, so keep reading.
It is much easier to fall when walking down a slope than walking up because of several separate reasons that act together. They include some physical forces, our body shape, and ground effects. Here is a short list:
- There is a component of gravity force that acts in the direction of the slope. This holds for both downslope and upslope motion.
- But there is a difference of this gravity force for the two directions. Your body experiences more force when you go downhill.
- Effective foot friction may be smaller when you go downhill.
- Lever arm of your foot is longer when you go uphill, and this is why you are more stable than going downhill.
- When you extend your front foot to put it on the lower ground, your center of gravity is effectively higher. So you are less stable.
- If you have a scree on a downhill path, it may slide down under your foot, and you will finish on your back. This is not so when you go uphill, you will fall forward and you have arms to prevent injuries.
All these reasons are explained in more detail below.
So why exactly are you more likely to slip and fall when walking downhill than walking uphill?
When you walk on a flat ground, gravity acts vertically from your body weight center, so there is no torque acting onto your body.
But when you walk on a slope, gravity remains vertical, yet it has a component down the slope. This causes a torque effect, see the pictures below.
This torque effect acts in the same direction regardless of your own motion direction. But its effects are different for the uphill and downhill walk, more below.
More gravity acceleration when descending
Downhill motion: Imagine you are stepping down, and you are naturally pulled by gravity. The place where you put your foot is lower than the one where your other foot is located. We actually partly fall in each and every step.
You can understand it better if you first visualize a walk on a flat ground (the picture above left), and compare with a slope (the picture on the right).
So you have to extend your foot to reach the ground, and your body will be accelerated a bit. If you land hard, you will feel this in your knees. This is what I discussed in detail in my separate text with a comparison of downhill and uphill walk.
In other words, you use your muscles against gravity, but you may not be successful with every step. If you do not brake your movement correctly, you may lose balance and fall.
In fact, on extreme downhill, it may be best to descend by walking backwards. There is a sketch about this in my text about walking down an extreme downhill where I describe it as a backward scramble. In this case, unless you fall backward, your hands are close to the ground, and you have more chances for self-arrest.
Uphill motion: Compare this all with an uphill movement. Your foot is placed on a higher ground, so there is no additional acceleration. Of course, it is harder to go up, but you are more stable.
So how to deal with this extra force in downhill walk? I am sure most of you know this already from your own experience, but here is what to do:
- It is best to walk at a small angle, i.e., zig-zag and walk switchback style. Why? You will have less ground difference with every step, and less acceleration. See more in my text about walk in extreme downhill.
- Make shorter steps. I am sure you will do this instinctively, nobody needs to tell you this. The reason is the same, you will experience less acceleration with each step. Your knees will also be grateful to you.
Friction may be effectively smaller when you go downhill
What I mean with this is as follows.
Downhill walk: In this case we practically fall into every step. Then we have to use muscles to arrest further motion. If the foot slides, this is then dynamic friction that is lower than static friction.
On a scree downhill walk, you will likely dig the scree with your heels and this sliding effect is reduced. But this causes other stability issues as your calves are not engaged properly and they do not provide their usual shock absorption.
Uphill walk: Here, our step is not a fall, so the foot is on the ground and we have better chances to keep it static, and static friction works better.
You will likely also lean forward, and this will bring your center of gravity closer above your front foot position. So there will be maximum pressure on the ground and friction will be better.
Note also that here you use your quads more, and these are big muscles so you have a better control of your body. But even if you lose balance in a forward step, you can fall back to your back foot.
This is not so in the downhill movement where you completely depend on the front foot and you can not get back to your back foot after you start making a step.
How to deal with this?
- Use trekking poles. This improves stability. You are able to lean forward and to shift your gravity force center above the place where you put your foot. This will also improve friction and you will feel more stable.
- Have hiking or mountaineering boots with a good grip. If you are not sure about the first group, think about Salomon or Lowa boots, I have them both. As for mountaineering boots, I would always recommend some of the Italian brands that I use myself, like Scarpa or La Sportiva.
Foot lever arm effect
You are most stable when your weight is centered on your feet. But this is not always so when you walk on an uneven terrain. So sometimes you are with your toe on the ground, and sometimes with your heel.
To understand the consequence of this, think about your foot as a lever arm. When you face uphill, and your weight is on the front of your foot (toes), you are more stable than when you face downhill and your weight is on your heel. It is easier to keep balance in the first case because lever arm is longer.
Center of gravity is effectively higher for downhill walk
You can visualize this in the following way. Imagine you stand still. Your center of gravity is directly above your feet.
Now you make a step downhill. Before your foot is on the ground below you and before your weight is on it, your center of gravity is higher from the ground than what it was when you were standing still.
Now face uphill and make a step. As you shift your body weight to the front foot, your center of gravity becomes closer to the ground.
You are more unstable with the center of gravity higher, and you will fall farther when you go downhill. So at tricky passages, lowering your center of mass will help.
So these are some of the reasons why it is so much easier to fall when walking down a slope than when walking uphill. As you realize, there are many factors that may destabilize you. Your body muscles react continuously on all this, and this is why we have so much pain in muscles after a hard walk in the mountains.
There is no doubt it is far more challenging to walk downhill than uphill, and I hope I was able to show this clearly. Let me know if you have something to add, there is a comment box below.
You might want to read also my text about factors that make us tired when walking uphill. Bookmark this site and come again, you will always have new texts added here. Thank you for reading and have a nice day.