Performance testing was part of my preparation for a sub-three-hour marathon in the Crushing3 project. I wanted to understand my fitness through testing rather than relying only on formulas and watch readings.
This account was originally published on 19 December 2017. The results and recommendations relate to that stage of my training.
Why I chose performance testing
As a recreational runner, I wanted to understand my own capacity and make better sense of training intensity. I visited High Level Center and 4SL to experience a treadmill test and see what I could learn from the results.
How my treadmill test worked
According to my report, the test started at 10 km/h. Speed increased by 1 km/h every three minutes, and I continued until I chose to stop.
A mask enabled respiratory gas analysis. Oxygen uptake, ventilation and heart rate were recorded, with finger-prick blood samples used to assess lactate concentration. The report identified an anaerobic threshold from changes in respiratory measurements and lactate.
My experience: progressively harder stages
I normally run outdoors, so the treadmill took some getting used to. The start felt manageable, but each stage became harder. My original account recorded 24 minutes of running and completion of the three-minute stage at 17 km/h, approximately 3:32 min/km. I did not attempt the 18 km/h stage.
What the results showed
Heart rate: 196 bpm. This was the highest reading I reached during the test. Formulas had previously suggested roughly 183–186 bpm. That compares my observed test reading with formula-based values; it does not establish heart-rate targets for other runners.
160 bpm in my recommendations at the time. I had previously capped easy runs at 155 bpm without a personal test to support that limit. The report referred to 160 bpm as an intensity for that training phase. I do not treat this as a rule to make every easy run faster or as a promise of a specific pace improvement.
VO₂max: 66 in the report. Two days earlier, Garmin had shown 56; my highest previous watch estimate was 64. These are my historical readings, not a controlled comparison of device accuracy.
Garmin and laboratory testing
A watch estimates VO₂max from training data. Laboratory measurement uses respiratory gas analysis during exercise, a distinction also explained by Garmin. My result therefore does not support my original blanket conclusion that watches cannot be trusted. It helps to distinguish a device estimate from a measurement taken during a particular test.
How I used the recommendations
The report recommended work on aerobic capacity and exercise economy. It gave me a reference point for marathon preparation, but I do not turn those historical intensity and volume recommendations into a training plan for the reader.
The original article also quoted advice about iron, vitamin C and folic acid. I do not present that as supplementation guidance: without the full documentation, I have no basis for extending that recommendation to other people.
What I took away from the test
The main benefit was learning about my own results and moving away from arbitrary heart-rate limits. I retain these numbers as a record of my preparation and interpret them in the context of that test and its recommendations.
Follow the rest of the journey in Crushing3 or read my Manchester Marathon race report (Polish).