Impact force, loading rate and pronation

Impact force, loading rate and pronation

What are those metrics?

Impact force and loading rate

Your gait is divided in different phases:

  • When your foot is on the ground: absorption and propulsion phases
  • When your foot is in the air: swing phase

Impact force if the force applied by your foot on the ground during the absorption phase. Loading rate is the speed at which the impact force is applied. Together they quantify the shocks sustained by your whole body.

Pronation/supination

Pronation refers to the inward roll of the foot, whereas supination is the opposite of pronation and refers to the outward roll of the foot.

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How should I use them?

Impact force, loading rate and pronation/supination are mainly related to injuries. They do not have a direct role in performance.

We have a complete section which lists the most common injuries and their related metrics. Please refer to this section to get more details on how to use those metrics!

 

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Foot strike: does it really matter?

Foot strike: does it really matter?

What is foot strike?

Foot strike is the region of your foot that lands on the ground. It shows if you’re a heel-striker, midfoot-striker or forefoot striker.

The science behind foot strike

There has been many studies on foot strike. Here are key facts on foot strike:

  • Forefoot striking increases metatarsophalangeal and ankle joint load but decreases knee load (1)
  • Barefoot running was performed with higher cadence and shorter strides.(2)
  • Rearfoot pattern may reduce Achilles tendon stress, strain, and strain rate (3)
  • Even Kilian Jornet adapts his foot strike during a run (4)

How should I use it?

From a biomechanical point of view, rear foot striking is associated with higher knee load. On the other hand, fore foot striking creates higher mechanical constraints on the metatarsal bones (your front foot) and on Achilles tendon. Foot strike can therefore be associated with risk of injuries.

There are no clear conclusions on foot strike influence on running performance.

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How can I measure it?

There are no tools outside of running labs to measure foot strike. They usually do this with video analysis or with force plates.

Being the ultimate running wearable FeetMe Sport can measure foot strike. It is a key parameter in evaluating risk of injuries. You’ll find more details on the injuries associated with foot strike in our Injuries section.

If you want to evaluate your foot strike and evaluate your risk of injuries, FeetMe Sport is exactly what you need.

Propulsion force: key phase in your gait

Propulsion force: key phase in your gait

What is propulsion force?

Your gait is divided in different phases:

  • When your foot is on the ground: absorption and propulsion phases
  • When your foot is in the air: swing phase

The propulsion force is the force you apply on the ground during the propulsion phase of our swing. Therefore, it is the force that propels you forward.

The science behind propulsion force

The propulsion phase has been widely analysed by scientists. Here are key facts:

  • Propulsive force is increased by greater forward leaning (1)
  • Propulsive phase has the strongest direct link with running economy (2)
  • Body weight support and forward propulsion comprises about  80% of the metabolic demand of running (3)
  • Strides which are too long will require considerable power during propulsion (4)
  • At slower stride rates (and longer stride lengths), the muscles need to develop high external power during propulsion to overcome large braking forces (5)
  • Propulsive phase is key for running economy (6)
  • Propulsion force is directly related to plyometric and resistance trainings (7)

How should I use it?

Propulsion force is a key parameter in your running stride. It will greatly influence performance and efficiency. There are two way of using propulsion force:

  1. If you decrease your propulsion force while keeping the same speed, you enhance your running economy. You will run longer!
  2. If you increase your speed but keep the same propulsion force, you are optimising the force you are generating. You will run faster without getting exhausted!

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How can I measure it?

There are not many tools outside of running labs to measure propulsion force. Researchers use force plates which allow measuring one stride. FeetMe Sport is the ultimate running wearable and measures your propulsion force during any run.

Start measuring and optimising your propulsion force with FeetMe Sport go run more efficiently!

Power: running revolution

Power: running revolution

Please see our previous article about running efficiency to get a detailed introduction to power measurement.

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.

The science behind power

There is almost no scientific articles on power in running, mainly because there was no tool to measure power, until now.

However, power has been used for decades in cycling. It has revolutionised the way professional cyclist train. Most interpretation of power in running is therefore based on the knowledge developed on cycling.

How should I use it?

We can break down power in two main components: vertical and horizontal power. Vertical power is the energy you spend to make you move vertically, whereas horizontal power moves your body forward.

To be as synthetic as possible, you want to decrease your vertical power to improve your running efficiency (just like vertical oscillation).

Horizontal power can be used in two ways:

  • If you keep the same speed, you want to decrease your horizontal power. It means that you are using less energy and keep the same speed: you will be able to run longer!
  • You can also try to increase your speed keeping the same horizontal power. It means your are going faster while using the same energy: you will run faster without getting exhausted!

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How can I measure it?

There is currently no validated tool to measure power in running. At FeetMe, we are validating our measurements to make sure we bring to runners a device that can accurately measure power consumption.

To start training with power, get FeetMe Sport, your personal running coach!

Vertical oscillation: improve your running efficiency

Vertical oscillation: improve your running efficiency

What is vertical oscillation?

When you run, your center of mass (basically your pelvis) moves up and down. Vertical oscillation measures the amount of “bounce” – i.e. vertical up and down movement of your center of mass.

The science behind vertical oscillation

Scientists have studied vertical oscillation very widely. Here are the key facts:

  • Lower vertical oscillation appears to benefit running economy (1)
  • Significant correlations between running economy and vertical oscillation of the center of mass (2)
  • There is a significant decrease in vertical oscillation in mountain ultra-marathon race (3)
  • Increasing vertical oscillation leads to increase in oxygen uptake, reducing running economy (4)

How should I use it?

Collectively, these results imply that reducing the magnitude of vertical oscillation will increase the running economy. If you reduce your vertical oscillation, you will spend less energy bouncing (and you can use this energy to run faster or longer).

Vertical oscillation is therefore a key parameter for running economy.

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How can I measure it?

There are no robust tools outside of running labs to measure vertical oscillation. Watches can’t measure what’s going on under your feet and therefore cannot measure accurately your vertical oscillation.

FeetMe Sport will help you measure and reduce your vertical oscillation. Get your personal running coach to increase your running economy!

Understanding ground contact time

Understanding ground contact time

What is ground contact time?

Ground contact time is pretty straightforward: it is the amount of time your feet are in contact with the ground at each stride.

The science between ground contact time

Ground contact time has been widely analysed by scientists. Here is a list of key facts:

  • Short ground contact times may contribute to the exceptional running economy of Kenyan runners (1)
  • Shorter ground contact time is correlated with increased running intensity (2)
  • Rearfoot strikers have a longer ground contact time (3)
  • Longer ground contact time are associated with lower VO2 values (3)
  • Short contact times is important for both economical running and high top running speed in distance runners (4)
  • A shorter contact time contributes to higher running economy (5)

How should I use it?

Decreased ground contact time is highly correlated with running economy and performance. A shorter ground contact time will help you run faster and longer.

Decreasing ground contact time can be achieved in any runner with specific exercices.

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How can I measure it?

There are not many validated tools outside of running labs to measure the ground contact time. Labs use force plates or video analysis to measure your ground contact time. Pros have tools that can measure their ground contact time on 2 or 3 steps max.

However, there is no validated tool that can measure ground contact time during a complete run. Being the ultimate running wearable FeetMe Sport provides you best in class ground contact time measurements and helps you decrease your ground contact time.

Get FeetMe Sport, your personal running coach, and become a faster and more efficient runner.

Wearable devices and injury prevention. Meeting with Philippe Rouch : Head of Georges Charpak biomechanics institute.

Wearable devices and injury prevention. Meeting with Philippe Rouch : Head of Georges Charpak biomechanics institute.

Philippe Rouch is Professor and Director of the Institut de Biomécanique Humaine Georges Charpak at Arts et Métiers ParisTech. He graduated from the Ecole Normale Supérieure de Cachan and obtained a PhD in medium vibrations modeling in 2001.

Since 2010, he joined the Laboratoire de Biomécanique at Arts et Métiers ParisTech to develop musculoskeletal models especially for sport biomechanics. By coupling EOS 3D imaging, EMG, motion analysis, these combined models allow to compute performance criteria or injury risks criteria.

He’s currently working with the French Federation of golf, soccer, rugby, basketball, ping-pong and with INSEP. He will present one example on the influence of the playing surfaces on the injury risks for soccer or rugby players.

Looking at Tiemppo, he sees the potential for injury prevention among athletes with accurate measurements and feedbacks.

We spend some time with him getting his feedbacks about Tiemppo and FeetMe‘s technology.