Measuring My Return to Running Fitness

When I had my first bout of getting into running in the 2011/2012 period it was clear to me that I should have some sort of benchmark to measure my progress. While it was possible to measure VO2Max and heart rate zones with an expensive test I didn’t want to rely on that. Instead I devised my own running fitness test that I could repeatably do over time to see changes in my cardiovascular fitness. I am now nearly a year from the beginning of my health reboot and nine months since starting to incorporate running into that. I have been doing running training pretty consistently since August. It started off as relatively high intensity running workouts. Starting in October I shifted to a very Zone 2, low heart rate zone, style of training. After slacking off a bit in the end of year holiday period I buckled down starting at the end of January. I’ve been making slow but study progress ever since.

For years I’ve wondered if I could ever get to those cardiovascular fitness highs again. With this very different training style than what I applied before I was thinking I may be sacrificyng shorter term “faster” cardio performance levels for better base building. Having now performed the test again I think I actually am getting both at the same time. In fact I think I am almost at the same performance I was at in my best trained times.


In the beginning of this blog I briefly mentioned a self-defined cardio fitness test . I don’t recall exactly why a 10 minute mile pace became my benchmark. Maybe it was the nice round number. Maybe it was because running a 12 minute mile pace on the treadmill back then always felt a bit awkwardly between too fast for fast walking and not fast enough to run. Maybe it was because that is the speed one needs to break a 4 hour and 29 minute finish of the marathon with some margin, an artificial benchmark I set for myself since that was Oprah Winfrey’s first marathon finish time. Still to this day the 10 minute mile pace is something I fixate on. However I arrived at that magic pace being “my thing”, once I got fit enough to actually sustain that I decided it’d be interesting to actually benchmark myself with it. To do that I came up with a “standard” treadmill test. The steps of the test are:

  1. Warm up: 5 minutes at 3.5 mph on a 1 degree incline.
  2. Stretching: A standard full body stretch routine
  3. Core Calibration: 20-30 minutes at 6 mph (10 minute mile) pace on a 1 degree incline.
  4. Recovery Calibration: Below sequence on a 1 degree incline
    • 0.25 miles at 3.5 mph pace
    • 0.25 miles at 3 mph pace
    • 0.25 miles at 2.5 mph pace

Originally the test only ran for 20 minutes but as I was conquering longer distances I decided I needed to add an extra ten minutes to confirm that I was at a heart rate plateau at that pace. Ideally I would be able to sustain that pace for a full marathon distance or longer and in a low enough heart rate to be in Zone 2.


I ran the test several times in the 2012-2014 period when I was my most active with fitness and running. At the time I tried to be very methodical in how the test was executed. I would do it on the exact same treadmill at the same facility each time. I tried to match the time of day and my routine leading up to it as well. Even with all of that the calibration of the treadmill is always in question over a couple of years. Now that I’m having to do it at a totally different location it’s possible that the treadmill speed will have even more variance. Still, we can get some pretty good rough order magnitude results out of all that.

That all said, the performance back in the day varied wildly, as my fitness level changed. As one can see from the graph (which also includes the measurement from last month) it really ran the gamut:

Calibration Run data from 2012 through March of 2024

We can see a whole stack near the top where I really had to push into Zone 5 to finish the runs. These weren’t maxing out my heart rate at the time, but I was definitely pushing myself to finish. Then there were times when I could run it for 30 minutes and it seems that my heart rate plateaued in a sustainable zone. Those two longer runs were the summer before both my half and my full marathons, respectively. My two best performances, before this year, occurred in the trial run done on the 31st of May in 2012 and the 1st of October in 2013. The first was a week after the first 10K I ever ran. That period was the first time I ever felt that strong in running ever in my life. The second time was near the 75% way mark of my training for my first, and to date only, marathon.

It therefore tickled me that the calibration run that I did at the end of last month on the 29th of March was right smack dab betwen the two of them. There is a grain of salt I have to add for the fact that I don’t know what the relative calibration of these two treadmills actually are relative to each other. But the difference compared to what I was against those two summer runs is pretty stark. I wrote about some of the runs I did around the time of the July 2013 test . Before this test if you had asked me if I was as fit as I was when I ran those dunes in PTown I would have told you an emphatic “no”. Presently I’m running those longer runs at 12-13 minute mile pace. I ran that PTown run at an 11:38 pace. That’s a full minute per mile faster. Other long runs about that time were between the 10:30 and 11:30 pace as well. So obviously I was fitter back then, right?

Well, actually I think the difference wasn’t my level of cardiovascular fitness but instead me pushing my heart rate zones way higher for longer. Looking at the average heart rate of my long runs now I’m in the high-130s trying to max out at 140 bpm. The average heart rate on those runs back then was at or just above 170 bpm! Subtracting one year off heart rate zones for every year beetween these runs would mean running those equivalent runs pushing 160+ bpm. That’s at least 20 bpm faster. I found some longer runs from that time period that I did in Hawaii. Due to the scenery I slowed down a bit to enjoy myself a bit more. Those paces were more like 12:00 pace, essentially where I was running this last weekend. The average heart rate for those was in the mid-150s. Again crudely adjusting for age that would be equivalent to the mid-140s today. All of that is a long winded way of saying that both according to the test I ran and the historical data from the time I think it is clear that I am now back in the peak cardiovascular performance levels I was at back in the day! Hooray for me.

Now the problem is if I can at the very least keep that level up for an extended period of time at the very least. Ideally I’d love to actually be able to exceed those performance levels by maintaining consistent training even longer than I already have. This is definitely the longest I’ve been consistent with training in my entire life. Even back in my peak running days I was at best consistent with getting a couple weekly runs in. Even that period was really a bit over a year leading up to my first half marathon, then a several month gap before I spent six months training for my first marathon. None of those periods had such consistent cross-training though.

It will be interesting to see where my fitness levels can go if I can keep up my consistency. That is a big if. Even just a couple months of maintaining consistency but pulling back to easy effort saw a good amount of drop off in my performance, as measured by both VO2Max and increase in pace. I’ll need slow down periods like that over time I’m sure. But maintaining longer periods of growth with easy but not zero activity periods will hopefully allow me to keep driving my performance forward for some time. Can I meet or exceed that mythical sustainable 10 minute mile pace? That is to be determined. But I’m looking forward to the process of finding out regardless of whether I get there or not.