It’s a jungle out there
A lot of fitness wearable ventures are currently focused on delivering what I like to call ‘lab tests in the wild’. That is, they want to be able to deliver metrics like VO2max at the end of people’s business-as-usual workouts, rather than in laboratory controlled conditions. It’s a worthy goal, but I get the sense that few of these companies know what they are getting into.
Here are some of the things that I’ve found need addressing during my own team’s algorithm development:
- Sensor accuracy – for instance how GPS readings alter in city canyons, on running loop tracks, and for seemingly no good reason
- Heart rate anomalies from strap issues and warm-up/warm down effects, or as the result of adrenaline, temperature, altitude, and autonomic suppression
- Running on trails rather than pavements, or running with a slower friend
- The effect of incline on various metrics (a delayed one in the case of heart rate).
If these are being addressed in the jungle lab tests out there, then I haven’t seen evidence of it. And I assure you that the impact of these factors can be very big. If you’re fit, but would like a leading device to contradict you, go for a run with it in Manhattan on a hot day.
If we take a step back and try to consider the purpose of these performance metrics, it is to be part of a system that helps us to get fitter – that is, to measure progress. Progress is something that happens over time, and so trend measures are going to be the most useful.
A good fitness program is training both limbs and lungs. Therefore trends in the performance of both of these need to be reported to people who are trying to improve (and the program altered to reflect these trends). A snapshot that bounces all over the place – not so much.