11 November 2017
The whole article can be expressed briefly this way: When walking downhill, lean forward. The rest will elaborate on why, and what other things to consider to improve our walking technique and make it safer. The article is divided into four sections:
- Motivation for this article
- Introduction to physics of walking
- Walking with a backpack
- Walking in the Middle Ages
Every now and then I notice someone slipping or even landing on their bum while walking downhill on a muddy track. While this is sometimes unavoidable, there is a number of things we can do to reduce such incidents.
Sport NZ lists as number one risk of tramping: "Injuries, e.g. from falls." (see here). While the Heinrich's pyramid may not be always applicable, I feel that in these circumstances it is still a useful tool to think about. The idea is that by reducing amount of unsafe acts and near misses (typically the bulk of all incidents) we are also likely to reduce a chance of more serious injuries (typically very few incidents):
Introduction to physics of walking
Walking technique is only one of the factors that can contribute to an incident. There are many other factors: Level of fitness, exhaustion, inattentiveness, weather conditions, terrain, etc. The counter-intuitive thing about walking technique is that we learn to walk early in our lives, therefore we usually don't seek instruction in how to walk later on.
I would like to focus on one specific aspect of walking technique: positioning of our centre of weight in relation to the terrain gradient. Let's have a look at a person walking upright downhill:
The person's centre of weight (red spot) is pulled down by Earth's gravity (blue arrow). This force is directly transferred to the person's feet and interacts with the surface they are standing on. There it resolves into two parts: Green force perpendicular to the surface, and yellow force pushing the feet down along the surface. If the friction between the feet (shoes) and surface is smaller than the yellow force, the feet will start sliding down.
How can we eliminate the yellow force pushing us downhill? It turns out this can be done by leaning forward. If we lean so far that we are perpendicular to the surface, then this force will be eliminated completely:
In this scenario the blue gravitational force will be resolved into two components at our centre of weight: Green force pushing us into the surface we are standing on, and orange force pushing us off balance. To prevent falling over we need to counteract the latter with light blue force in the opposite direction. We can achieve that by engaging our core muscles. Another important condition is that our centre of weight is not further than tips of our toes.
Obviously, this is an oversimplified scenario as it assumes we will be just standing there. When walking we need to consider more factors:
- Temporarily we can lean further than our toes as long as we keep moving. Though we need to be able to stop in a controlled way when required.
- By leaning forward we are increasing a risk of tripping over when our shoe catches on an obstacle, other leg, etc.
- With each step that we use to slow down or stop our movement, we are also generating a push that can get our feet sliding downhill. Again this works against the friction between our shoes and the surface; we are safe from sliding down only when there is enough friction.
- If we do end up sliding down, leaning forward improves our chances of staying in control of that slide.
There are other things that can be done to reduce risk of a fall when walking downhill:
- Increase friction between our shoes and surface. For example by using yaktrax, or waiting until the track dries up.
- Make small steps, especially when trying to slow down our movement. This will reduce the amount of downhill push with each step, while the friction remains constant.
- Walk slower. This will also reduce the amount of downhill push with each step.
- Run down a steep section if we can do it safely, and if we can safely stop later on. This approach obviously requires lots of confidence and careful planning of our speed and trajectory.
- Use one or two walking poles. However depending on the terrain this may or may not work to our overall advantage. Think of walking in the bush where poles could catch on surrounding vegetation and throw us off balance.
- If you hold on trees or other objects by the track, make sure you are still leaning forward at all times. When you lean back your feet are more likely to slide out from underneath you.
We can also consider some long-term mitigation:
- Improve our core strength and stabilising muscles. Talk to your physio or personal trainer about a suitable program.
- Learn skiing. To lean forward will be one of the things any skiing instructor will repeat endlessly. This comes in handy if we do end up sliding down the hill, as our skiing skills will help us to stay in control of that slide.
- Pick up a hobby that improves our stability. Dancing is a good example, as practising good dancing technique will strengthen our core and improve stability - especially spinning and turning in a controlled way. Various circus performing arts could be great too.
- Practise walking in challenging situations whenever it is safe to do so. For example never miss an opportunity to cross a stream by balancing on a log or do some boulder hopping. Pick rougher tracks for your trips or regular basis. Turn it into fun challenges for yourself.
Walking with a backpack
When carrying a backpack, the centre of weight of the backpack should be as high as possible and as close to our body as possible. There are two reasons for this:
- Our spine is a bit like a stack of coins. It can carry much bigger load when we push from above than if we pull to the side.
- By keeping its centre of weight high and close to our body it will be easier to shift our overall centre of weight forward or backward, as we walk downhill or uphill. Backpack adjustment straps can be typically used for that while walking.
Walking in the Middle Ages
Explore a little bit of history of walking. Here is a short video describing how people used to walk in medieval times, before the invention of fixed-sole shoes.
Please let me know if you notice any issues or inaccuracies in this article.
Article Walking Technique by Tomas Sobek is licensed under a Creative Commons Attribution 4.0 International License.