# Do Spikes Increase Friction? Benefits of Wearing Spikes for Runners

• aspodkfpo
In summary: There is a small gain in speed, but also a small extra expenditure of energy. Yes, wrt the pushing in, in effect you are running uphill slightly, like running on soft ground. There is a small gain in speed, but also a small extra expenditure of energy.
aspodkfpo
Homework Statement
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Relevant Equations
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Does wearing spikes increase friction if so how?

Is the main benefit of wearing spikes because it allows the runner to push against the side of the hole it makes, therefore directing a portion of the normal force forwards, unlike normal running where friction pushes the runner forward?

Middle and long distance runners in track often don't wear shoes with spikes. This is because they aren't pushing hard enough that there is a risk of slipping https://kaitcphysicsoftrack.weebly....rip onto the,spike makes - no friction needed.

How does not pushing hard enough result in a risk of slipping? Or is this statement untrue and if so why?

Because of the coefficient of friction, there is a maximum horizontal force through contact with the ground. This also depends on how hard you can push into the ground.

If you want more than the maximum you get from simple friction then you need spikes. Sprinters may need this at least for the high acceleration phase.

Ultimately, using spikes on a good track may be less efficient, which is not a problem for sprinting but is for longer distances.

Lnewqban
PeroK said:
Because of the coefficient of friction, there is a maximum horizontal force through contact with the ground. This also depends on how hard you can push into the ground.

If you want more than the maximum you get from simple friction then you need spikes. Sprinters may need this at least for the high acceleration phase.

Ultimately, using spikes on a good track may be less efficient, which is not a problem for sprinting but is for longer distances.

Why is it less efficient? It seems like getting spikes into the ground doesn't take anymore energy than running without spikes?

aspodkfpo said:
Why is it less efficient? It seems like getting spikes into the ground doesn't take anymore energy than running without spikes?
You might have to look at specific sports science to get the best answer to that. Spikes have to be pulled out of the track with every step. Over a distance race that small extra effort might make a small difference. If you take the extreme case of very long spikes, then clearly it would be an effort to move at all!

Lnewqban
PeroK said:
You might have to look at specific sports science to get the best answer to that. Spikes have to be pulled out of the track with every step. Over a distance race that small extra effort might make a small difference. If you take the extreme case of very long spikes, then clearly it would be an effort to move at all!
When being pulled out, friction is exerted by the side of the walls downwards, thereby resulting in more energy expended?

aspodkfpo said:
When being pulled out, friction is exerted by the side of the walls downwards, thereby resulting in more energy?
Yes, there is friction on the sides when you pull something out. If you stick a knife or spike into something it takes effort to extract it. For running spikes that must be a small extra effort, but may add up over thousands of strides. And, if you don't need the extra grip that the spikes give you, then it's wasted effort. If you are sprinting, then the extra effort over a few dozen or a hundred strides is negligible, but the extra grip may be invaluable in powering along.

That's the simplistic theory I can give you. Note that I've qualified everything I've said, as I'm no expert in the science of running shoes. If you want to know more, then I'm sure the Internet has plenty on the sports science of running spikes.

aspodkfpo
aspodkfpo said:
When being pulled out, friction is exerted by the side of the walls downwards, thereby resulting in more energy expended?
Then you push them in, you are dissipating energy into kinetic friction. When you pull them out, you are dissipating energy into kinetic friction. It is a lose-lose situation.

jim mcnamara and aspodkfpo
jbriggs444 said:
Then you push them in, you are dissipating energy into kinetic friction. When you pull them out, you are dissipating energy into kinetic friction. It is a lose-lose situation.
Yes, wrt the pushing in, in effect you are running uphill slightly, like running on soft ground.

## 1. Do spikes actually increase friction on a runner's shoes?

Yes, spikes do increase friction on a runner's shoes. The spikes, which are typically made of metal or rubber, dig into the ground and provide more grip and traction, resulting in increased friction.

## 2. How does increased friction benefit a runner?

Increased friction can benefit a runner in several ways. It allows for better traction and grip on the ground, which can help prevent slipping and falling. It also allows for more efficient use of energy, as the runner does not have to work as hard to maintain their footing.

## 3. Are there any drawbacks to wearing spikes for running?

While spikes can provide benefits for runners, they do have some potential drawbacks. They can be uncomfortable to wear for long periods of time and can cause blisters or irritation on the feet. Additionally, they are not suitable for all types of surfaces, such as pavement or indoor tracks.

## 4. Do spikes improve performance for all types of runners?

Spikes may not necessarily improve performance for all types of runners. They are most beneficial for runners who compete in track and field events, such as sprints or hurdles, where grip and traction are crucial. Distance runners may not see as much of a benefit from wearing spikes.

## 5. How often should spikes be replaced?

The frequency of replacing spikes depends on the type of spikes and the amount of use they get. Generally, metal spikes should be replaced every 4-6 weeks and rubber spikes should be replaced every 3-4 months. It is important to regularly check the condition of the spikes and replace them when they become worn down to ensure optimal performance and safety.