What are we measuring? What is a 'g'?

  • g is simply the symbol used to represent the acceleration value of an object during free fall near the surface of the Earth. The value is 9.8 m/s2 or 32.17 ft/s2.
  • In the case of an impact or a shock, the ‘g-force’ acting on an object can be very large during a short time. If for example the sensor indicates a value of 5g, it means the ‘deceleration’ was 5 times g = 49 m/s2.
  • For the specific case of running, when the foot hits the ground, it will ‘decelerate’ at a specific rate until it reaches a complete stop. The TgForce sensor is actually measuring the ‘deceleration’ rate at the tibia when hitting the ground.
  • A higher ‘g’ value recorded by the sensor means more stress was felt by the tibia during landing.

What is the PPA?

Peak Positive Acceleration of the tibia is the maximum acceleration that occurs during the impact phase of running. The PPA has been used in numerous scientific studies along with the vertical loading rate. However, measuring the vertical loading rate requires an instrumented treadmill and is typically used in a laboratory environment.

Why do we have to attach the sensor directly to the tibia; why not attach it to shoes?

  • Attaching the sensor to the anteromedial aspect of your tibia will provide you with real impact data affecting your body while running.
  • Shoes are made of various materials that attenuate impact at different rates. As the shoes age, materials deteriorate and the inner properties change. Environmental variables like temperature and humidity also affect the shoe’s response to impact.
  • What we are interested in is the impact level sustained by your body, not the shoe.

In summary, tibial attachment has been used in numerous scientific studies and is the recommended method for obtaining reliable results.

Can we use the TgForce sensor while running barefoot?

Yes, absolutely.

What's in the box?

  • One TgForce rechargeable wireless sensor
  • One USB recharging cable
  • One Velcro(tm) band for attachment

The TgForce Companion App for iOS is available for free on the App store.

Are you shipping to international locations?

Yes, we  ship to international locations.

What is the recommended gMax value?

If you are a runner, it’s recommended that you first consult an Exercise Specialist or Sports professional who can give you recommendations about defined targets and objectives. They can also help you transfer to another type of shoe or get started with your gait retraining as well.

How can I extract the data for further analysis?

Simply use the Export feature in the Settings menu. Data will be exported in CSV format using email messaging, including PPA, Average PPA, Time, Cadence, Step count.

What are the compatible devices?


  • iPhone 4s
  • iPhone 5
  • iPhone 5c
  • iPhone 5s
  • iPhone 6
  • iPhone 6 Plus


  • iPad 2
  • iPad 3
  • iPad 4
  • iPad Air
  • iPad Mini
  • iPad Mini 2

iPod: Touch 5th generation