GPS or foot-pod?
Measurement of speed and elapsed distance during sports can be done in several ways, most commonly with GPS or foot-pod. Frequently, you ask as about the advantages of GPS and foot-pod and what you should pick.
So let’s start with GPS.
With sport testers, you can meet two different versions; integrated GPS inside the sport tester or external GPS as a module for the sport tester. The integrated module is good because you don’t have to carry other device. However, the disadvantage is the size of the sport tester and the necessity of charging the sport tester like a mobile phone. With external module, you only change the battery inside it. The battery life of the sport tester is not really affected by having an external GPS.
Another disadvantage of GPS is that you have to be outside. In order for the GPS to work and receive signal from satellites, it needs to be able to see the sky. While sporting, it can happen that in a big forest or housing estates the GPS doesn’t reach enough satellites, and it doesn’t work for a while. However, you don’t have to worry that you’d loose a part of the route. Once the GPS reaches the signal, it calculates the data from the last spot where the signal still reached you. For example, if you’re running through a zigzag forest trail, the data will be distorted because GPS connects the point where the signal was lost with the first point where the signal was found again with a straight line.
Other disadvantage is deviation. It depends on the number of available satellites and also on the quality of the chip inside the GPS. If the chip is better and more satellites are available, there’s more accurate data. The deviation can be from two to 100 meters; it depends on the conditions.
Foot-pod is a second option for measurement of speed and elapsed distance.
Foot-pod, or foot speed sensor, is essentially a pedometer. After you put it on your shoe, it picks up vibrations caused by feet hitting the ground during walking or running. However, modern foot-pods can do much more. Thanks to some more advanced sensors they not only pick up feet hitting the ground, but also its acceleration and direction of moving. Thanks to that, foot-pod can record different lengths of steps, etc. The accuracy of foot-pods is at 98%. However, the precondition for accurate measurement is good calibration.
The disadvantage of foot-pods is the fact that it’s single-purposed. It’s only for running and walking. On the contrary, the advantage of foot-pods is that you’re not relying on satellites, unlike GPS, so you can measure even in the gym, big forests and anywhere where the GPS wouldn’t have a signal.
What to choose then?
If you’re a runner and you don’t need to measure speed and durance for example on a bike, you should buy a foot-pod. However, if you’re a multi-sport person, GPS is the right fit for you.