Every time your foot hits the ground, the ground pushes back with a force called the ground reaction force (GRF).
Within this GRF, two measures are especially important for understanding overuse injuries in running:
Impact: the shock your body feels at the moment your foot strikes the ground, expressed in G-forces.
Peak GRF: the maximum load your body experiences when your foot carries your full body weight, expressed in body weight (BW).
Typically, the measures are calculated in expensive and highly specialized lab-settings— not very practical for everyday runners.
That’s where OnTracx comes in. The sensor measures acceleration of your shin bone (tibia). Research shows that the peak tibial acceleration (PTA) is a strong reflection of the impact you feel. We’re also developing algorithms to estimate peak GRF in the future.
This means OnTracx can measure the impact of every step you take outdoors — where running really happens.
Why does this matter?
When the load you experience becomes greater than the load your body can handle, overuse injuries develop. These don’t happen in a single moment, but build up gradually through repetitive stress. In fact, overuse injuries account for nearly 80% of all running injuries.
With OnTracx, you can see your personal loading profile and progress gradually — reducing your risk and tailoring training to your body’s capacity.