Inertial footpod

An inertial footpod is a device used to track running measurements such as speed, distance travelled, pace, etc., which would generally only be available on treadmills or with a GPS unit.

[1] This device is usually small and attaches to a runner's foot.

It uses one or more accelerometers and processes several times a second to compute speed.

One example is the foot pod employed by the Polar S625x running computer.