When we run, all we care about is how to get faster from point A to point B. To achieve this, we need to objectively evaluate our performance in real time. It’s all about being more efficient. In order to improve our scores, we need to see in real time how efficiently we run.

How are performance and efficiency measured today?

There are numerous way of measuring the efficiency of a runner and we have been using what was out there: mainly cadence, speed and heart rate.

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Cadence and speed are not accurate

Cadence or speed is a straightforward metric which relates with performance. However, it highly depends on external factors (terrain elevation, terrain type, wind, temperature, etc.). It’s pretty simple: if you run efficiently at 175 strides per minutes on a track, what should your cadence be when going uphill or running on sand? There is no way to answer this question. Thus speed or cadence do not measure performance objectively.

Heart rate has a huge variability

Heart rate has also been largely used for training. But, it has major drawbacks.

First, heart rate does not respond instantly to effort: this phenomenon is called cardiac lag. If you increase instantly your exercise intensity, your body needs some time to realise you need more oxygen to sustain that effort. It takes a while (a minute or so) for your heart rate to adapt. Your heart rate does not represent your instant effort.

Furthermore, heart rate has a huge variability. Some external and internal factors, such as terrain, temperature, hydration, stress and even sleep will dramatically influence your heart rate. If you run the exact same run on two different days, you definitely won’t have the same heart rate profile, even though you run the exact same way. It is therefore impossible to compare heart rates among runners and on different runs for the same person.

 

But most importantly, does not measure how well you are running. Heart rate measures how much oxygen your body needs to keep going and thus the intensity of the effort. It does not measure how this energy is used to make you run faster or more efficiently. Worst case scenario: you can consume more energy without even going faster.

This is why we need a metric that measures your stride efficiency in real time and objectively (i.e. independently of external and internal factors).

Power is the next game changer in running

Physics 101: what is power?

Power is a force multiplied by a velocity. It is expressed in Watts (W). Power measures how much effort you apply on the ground with your feet to make your run. It measures the mechanical energy used in real time and does not depend on other factors.

Power has revolutionised cycling training being the only objective metric to measure your performance. However, it has not yet been adopted in running, simply because no running power meters existed. Until now.

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Power has two main components: vertical and horizontal power. Vertical power measures how much effort you use to lift you body in the upward direction. And horizontal power is the effort you use to move your body in the forward direction.

How can power be used in running?

Let’s take some simple examples to see how he can use power in running to become more efficient.

Elevation

If you usually train on a flat track, you will know what power you are able to generate (and remember, this does not depend on external and internal factors), say 234 W at 175 strides per minute. You then decide to go for a run on a hilly trail. When you are going uphill, you cannot maintain the same pace as on your usual track, but you can adapt your pace to generate the exact same amount of power (234 W). In that way you know you are as efficient as on your usual track, even if you are running at 120 strides per minute.

The same goes when the trail goes downhill, you will be able to rise you pace up until you create the same amount of power to stay efficient.

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Terrain surface

In the previous example, power is your reference to adapt your run to the elevation of the terrain. But power can also tell you how to adapt your technique to the terrain surface to stay efficient. All trail runners know this but, your stride should not be the same on asphalt, grass, sand, rocky terrain or snow. Once again, cadence, speed or heart rate cannot tell you how efficient your technique is on a specific terrain. But power can! If you know you can generate 234 W on your usual training track, then this is also what you can generate on all those terrains as power measures the mechanical energy your body can deliver.

For instance, on sand you need to distribute your pressure uniformly under your foot to generate the same power, and therefore reach the same efficiency. Being able to adapt your stride to all terrain requires to get this data in real time.

Stride economy

Running is not about getting faster, it is about getting more efficient. Let’s say you can generate the usual 234 W during a full 10k, but nothing more. You have run 8km and still have 2km to go. You struggle to keep the same pace but realise your power is rising up due to fatigue. You are using more energy to keep the same pace: your stride is definitely getting inefficient. You won’t be able to finish the race if you go on like this. Relax your body and focus on your stride technic. Keep that power down and you’ll be break a new record!

Want to join the revolution?

As you can see, power is a real game changer for running. It instantly and objectively measures the influence of your technique on your performance.  Because it measures efficiency, power is already a revolution for running. If you want to be part of this revolution, signup for updates about our new product!

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