An N of 1 — subjective feedback

Tom C W
5 min readDec 2, 2022

On my run today I was listening to an excellent podcast about Running (very meta I know). This particular episode focused on using subjective feedback for improving performance rather than only relying on objective feedback in complex adaptive systems (in this case, humans).

We live in a time of wearable technology, with smart watches that can measure all manner of things used by millions of people everyday. And along with the wearable technology are a variety of tools and apps to explore some of the data collected by the technology. I myself have a Garmin watch and have subscriptions to both Strava and TrainingPeaks.

If you explore each of the different tools you will invariably find something which indicates your ‘Fitness’ score. Each has a different algorithm to take data from your wearable and provide you with a fitness score. But is it really indicating my fitness? And does it actually indicate that I am in a better position to perform how I hope to?

Invariably the fitness score is in fact a score based upon a training load. More training load = a higher fitness score. And yes, in general, training more, will most likely improve fitness. A positive trend on a fitness score will probably indicate that I am getting fitter. But is this the most efficient way of improving my fitness? And most importantly, am I in the best place to perform when I want or need to?

I am an N of 1.

I am an Nof 1. There is only 1 me, there is only 1 you. And yet the ‘fitness score’ is based upon an n of tens, maybe hundreds of thousands. How the average of these tens of thousands respond to specific training loads does not always indicate how I or you will respond or adapt. And this is why subjective feedback is vital.

In the case of running, subjective feedback is often about feel. How do you feel, based upon your training load. And what is the context and conditions of this training? For instance, on today’s run, I undertook a route I know well. It is an 8 mile out and back with lots of elevation. I have ran this route many times, and can look through times and speeds for these runs…



Tom C W

Do Good, Be Awesome. Thoughts on startups, social change, awesome things, and possibly running.