There are plenty of ways to convince yourself that training is working.
The scales can move. Clothes can fit differently. A weight that once felt heavy suddenly feels manageable. You can look in a mirror and wonder whether the person looking back is beginning to change shape.
But I like data.
Not because every aspect of getting fitter needs to become a spreadsheet, but because numbers have a useful habit of cutting through how I happen to feel on a particular day.
And this week I’ve started to see some genuinely quantifiable evidence that what I’m doing is working.
Running again — cautiously
Yesterday was another small but significant step in my return to running.
The calf injury that stopped me in my tracks a few weeks ago has dictated quite a lot of my training recently. Cycling, swimming and strength training have allowed me to keep moving, but I’ve been deliberately cautious about simply deciding it feels better and heading out for a 5K.
So we’re rebuilding.
Yesterday’s session was:
6 × 2 minutes running, each followed by 2 minutes walking.
It doesn’t sound particularly dramatic, and that’s rather the point.
The objective wasn’t pace. It wasn’t distance. It certainly wasn’t Strava glory.
It was simply another controlled dose of running and another opportunity for the calf to tell me whether it’s ready for more.
The answer was encouraging: 0/10 discomfort throughout.
The route was undulating, so the cardiovascular effort was still reasonably high, but mechanically everything behaved itself. That’s another successful running session banked and another step towards being able to run continuously again.
The first target is straightforward: get back to running 5K comfortably and consistently.
After that?
Well, I might have started wondering what my parkrun PB looks like these days…
There’s a considerable amount of work between here and there, but for the first time in quite a while it feels like a question of when, rather than if.
The numbers are starting to move
One of the things I’ve enjoyed about the last few weeks is having enough consistency to begin comparing myself with… myself.
I’m not interested in what somebody else in the gym can lift or how quickly somebody else can run.
I’m interested in whether this week’s version of me can do something that last week’s version couldn’t.
And increasingly, the answer is yes.
Weights in the gym have gradually increased. Exercises are becoming more controlled. I’m paying more attention to posture and technique rather than simply moving a weight from A to B.
There’s one particularly simple example that makes me smile.
About three weeks ago, holding a plank for 30 seconds was genuinely difficult. I was hanging on waiting for the clock to reach zero.
This week I’m completing 45-second planks after an entire gym session and feeling comfortably in control of them.
That’s a 50% increase in duration in three weeks, but the bigger difference is how they feel.
The same thing is beginning to happen elsewhere. Loads are increasing, repetitions are becoming cleaner and movements feel more familiar.
Then there’s cardiovascular fitness.
That’s where the data gets particularly interesting.
Enter Zwift
For anyone unfamiliar with it, Zwift is essentially an online cycling environment that connects to an indoor smart trainer or smart bike.
You pedal a real bike indoors while your avatar rides around a virtual world. You can race other people, ride socially, climb mountains, follow training plans or just pedal around looking at computer-generated scenery while sweating all over the floor.
But the bit I’m particularly interested in at the moment is structured workouts using ERG mode.
ERG mode changes the relationship between you and the bike.
Normally, if I want to produce more power, I pedal harder or select a different gear.
In ERG mode, Zwift tells the trainer:
“Make him produce 170 watts.”
The trainer then continually adjusts the resistance to make that happen.
If my cadence changes, resistance changes to compensate. I don’t need to chase the target by changing gear.
The workout dictates the power.
And that’s incredibly useful for measuring progress.
Creating my own little fitness experiment
I’ve been repeating a short Zwift session.
It isn’t intended to be a full workout. It’s only around 15 minutes and consists of a warm-up followed by six very short, very high-power 20-second efforts, separated by predetermined recovery periods.
Because it’s an ERG workout, Zwift controls the power targets and the duration.
So, provided I repeat it under reasonably similar conditions, we’ve removed a lot of the variables.
The bike is the same.
The workout is the same.
The intervals are the same length.
The recovery periods are the same.
The requested power is the same.*
And therefore one of the really interesting variables left to observe is:
What does my heart have to do to produce that work?
Same job, lower cost
The heart-rate data from the last three weeks is already fascinating.
Looking at minutes 8–14 of each session:
| Minute | 2 weeks ago | Last week | Today |
|---|---|---|---|
| 8 | 155 | 146 | 139 |
| 9 | 160 | 151 | 142 |
| 10 | 163 | 155 | 148 |
| 11 | 165 | 155 | 145 |
| 12 | 166 | 158 | 152 |
| 13 | 170 | 158 | 149 |
| 14 | 169 | 163 | 153 |
That is a remarkably satisfying table to look at.
At minute 13, for example:
170 → 158 → 149 bpm.
There are other things that influence heart rate: temperature, hydration, fatigue, sleep, caffeine and even how effective the fan is at stopping me from turning the room into a sauna.
But the overall direction is difficult not to be encouraged by.
Next time Zwift will ask me to produce exactly the same output again.
If I can produce those watts while my heart rate progressively comes down, that’s quantifiable evidence of adaptation.
Not:
“I think I’m getting fitter.”
But:
“My body required less cardiovascular effort to perform the same external work.”
That’s the sort of progress I love.
Data doesn’t replace how I feel
There’s an important distinction here.
I’m not trying to turn every training session into a laboratory experiment.
Some of the best exercise I’ve done recently hasn’t involved chasing numbers at all. I’ve cycled with my daughter, rollerbladed through the countryside and simply enjoyed being outside and moving again.
That’s arguably more important than any heart-rate graph.
But the data gives me another layer.
The calf says 0/10 during a controlled return-to-running session.
The gym log says the weights are increasing.
The stopwatch says a plank that was difficult for 30 seconds is now controlled for 45.
The heart-rate monitor says a familiar cycling workload is becoming less physiologically expensive.
The scales are moving too.
None of those things individually tells the whole story.
Together, though, they’re beginning to tell quite a compelling one.
Three weeks isn’t enough time to transform anything.
But it is enough time to start building momentum.
And, increasingly, enough time to prove that the work is actually working.
Track. Train. Transform.
And tomorrow?
Another carefully controlled step towards that 5K.
Then eventually, perhaps, there’s a parkrun PB with my name on it.
