In this blog post, we review how to use the TgForce 3D sensors to monitor PPA (Peak Positive Acceleration of the tibia) from both legs simultaneously when running on the treadmill. 

When evaluating the tibial shock in a gait retraining program, it may be advantageous to use two sensors simultaneously (on both legs). 

  • It provides immediate feedback on both legs, saving time for both the runner and the kinesiologist
  • Immediately highlight any significant difference in PPA between the left and the right leg.

The procedure is relatively simple. With two iOS devices, pair each device with a TgForce sensor. Make sure to identify each sensor adequately (Left, Right) in the user’s settings. 

In the demonstration video, the runner attached sensors to the anteromedial aspect of the distal tibia. Some notes:

  • The treadmill is equipped with a cushioning feature 
  • Speed is set at 11.3 km/h (5:19 per km)
  • There is no slope on the treadmill 
  • Shoes are Brooks GTS-16
  • Two iPhone SE with iOS 12.4 for the real-time feedback

After the sesion, the average 3D impact (PPA) is 5.1g for the left leg and 5.3g for the right leg.

To demonstrate a situation where there is a significant difference in PPA between the legs, the runner switched the right shoe for a different type not designed for running (Adidas Superstar).
The difference in PPA is noticeable with the sensor on the right leg, recording an average increase of approximately 1g.

Further analysis is possible using the export feature of the TgForce 3D iOS App. For example, the two following charts were created using the MacOs Numbers application. In the second chart, the higher PPA recorded by the sensor on the right leg is evident and suggests an imbalance.

Running with Brooks GTS-16 – same shoes for both legs

Running with Brooks GTS-16 on left leg and Adidas Superstar on right leg to demonstrate imbalance