If You Don’t Measure It

You Can’t Improve It

If you don't measure it - one year of fitness trends

If you don’t measure it, you can’t improve it. The diagram on the left illustrates my Training Peaks fitness trend over the last year.

A year ago, I was ramping up my fitness for the annual Girona cycling pilgrimage, which was a precursor to Ride London in May. As is documented elsewhere, Ride London saw me in the ICU for 12 days with multiple fractures. The graph bottom right shows my fitness fall precipitously.

And then, my climb back. I have cycled, gone to the gym, and even taken up running—all to get back to fitness. And this morning, my fitness was higher than when I came into Ride London 2023.

With Girona only three weeks away I had planned some hilly climbs in the month leading into the trip. Three sessions of North London hills. And yesterday, an absolutely brutal loop through the worst the Surrey Hills has to offer.

When I finally got home, I was wracked in agony and was experiencing cramps. A long day in the saddle can do that for you. I don’t remember another day when I saw the gradient at 20% and over than yesterday. For a few seconds, I saw a reading of 28%. At 103 kgs, hills of that profile are no fun.

Relatively Strong

If you don’t measure it applies to other parameters, too. Garmin measures an approximation of VO2. This measure is increasingly seen as a good indicator of longevity – see this range of Peter Attia articles.

We can go into a long argument about the accuracy of this Garmin measurement, but it counts for me. Firstly, because I will track a trend over time and if I’m maintaining or improving, that’s a good thing. If I did the fully-scientific VO2 test with a mask and dozens of sensors clipped to me I would probably get a different number. But then I would need to do it again and again and again in order to see progress.

What I like about being in Garmin’s top 10% for my age and gender is the massive data pool. With millions of Garmin devices in circulation, my performance stacks up against a large peer group.

I have two more areas in my ‘if you don’t measure it’ category: sleep and Heart Rate Variability.

We are all aware of the importance of sleep in a wide range of physical and mental health areas. My trend for the last eight weeks is steadily downwards but still within the normal range. One to watch, for sure.

The other measure is Heart Rate Variability. This is another critical measure when it comes to establishing base fitness, and it’s a great early warning system; summary here.

My HRV is high, although yesterday’s smash fest has left my HRV with an amber signal, which tells me my recovery condition is marginal—a day to take it easy. It’s a good early indicator for colds and other illnesses. Quite often, I have seen my HRV fall in the days leading up to a cold.


There is no substitute for the ‘if you don’t measure it’ approach to fitness. Without points of reference, there is no way to understand whether you are genuinely making progress. Feel is a good indicator, but it isn’t definitive. The numbers never lie when looking at trends. I have settled on the three most essential measures available to us weekend warriors who don’t have access to full-blown sports laboratories. This routine fits into my life easily. Training Peaks and Garmin do their stuff in the background, while HRV takes me one minute with a finger sensor and app. However, for Apple and Garmin watches and Whoop wristbands, HRV is measured. I have found the wrist-based devices to be less consistent in measuring over a period, sometimes delivering wild swings for no reason.

Golden rule? If you don’t measure it, you can’t improve it.

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