Sunday, May 19, 2019

- One Year On

I have been running for a year now. My goal was to make this a regular habit, and I think I've succeeded. I run four times a week, for a total of 35-40km. Usually I run three times over lunch on weekdays, then a longer run on the weekend.

When I started I doubted that I would persevere for more than a couple of months. I thought I would hurt, I would get bored and I'd soon make excuses not to go out running any more. But running turned out to be quite fun and very satisfying.

Distance I run per week (green bars) and the average Polar "running index" (red line).

I believe the image above sums it up nicely. I went from complete beginner to 35-40km a week in about 6 months. The "Running Index" is a proprietary index of how good a runner you are. But it's really little more than the ratio of your heart rate and your running speed, with a log scale factor to account for the distance.

You see a lot of stuff when you run. Here a tiny "dekotora" ("decoration truck") near the airport in Naha.

Our heart rate is directly proportional to our effort. As we work harder our muscles need more oxygen, so the heart will beat faster to deliver it. As we get more fit our muscles become more efficient at using the oxygen; our lungs can deliver more oxygen to the blood; and the heart is able to pump a larger volume of blood with each beat.

Figuring out a detailed measurement is a little complicated. But you can divide your speed by your heart rate for a simple index of how well trained you are - a higher number means you are faster for the same heart rate, and so you're better at running (or whatever sport you do). Of course, as you run for longer you will get more tired, so the number will drop. To account for that you can adjust it with a logarithmic scale factor that depends on the distance. Something like

"index = log(a*distance) * (speed/heart_rate)".

You could find out "a" by fitting it to running data from a bunch of runners, so that the index is about the same from the beginning of a run to the end.

So if I'm getting better then why has the index been dropping since April? Summer, is why. Our blood doesn't just supply oxygen; it also cools us down. It transports heat from within the body out to the skin where our sweat will take it away. But any blood diverted to our skin is blood that's not going to a muscle. Our hearts have to work harder, our muscles get less oxygen, and we are running worse through no fault of our own. Our efficiency — and the running index — is similarly affected by hills, by humidity, by altitude and many other factors.

My weight over the past three years. The line is a two-week average.

I've also lost the weight I've gained since coming to Okinawa. In Osaka I got a lot of exercise from walking and taking the subway everywhere. Since coming to Okinawa, though, I mostly travel by car, and my job gives me little stress and plenty of free time. I gained about 3kg in the year and a half since coming here.

But since I started running I've dropped from 75kg back to 68-70kg. That's not mainly due to the running; exercise by itself doesn't make you lose weight. If you exercise more, you'll also eat more to make up for it. But I'm careful with what I eat and drink now (I've mostly stopped drinking alcohol) and in combination with running it's had a large impact on my weight.

Sunset in Osaka. Drawback of running is, you can't bring a good camera.

I really enjoy running. It's especially fun to run longer distances, and to explore new areas while running. I've been tempted to increase my distance and increase my pace even further, but I tend to get knee pain when I do. Stretching and other exercises help a bit, but ultimately I have to limit my distance and run mostly slow runs to stay injury free. The joys of growing older, I guess.

Will I continue? Yes, absolutely. It's fun, I feel good and I have no reason not to. I'm even thinking of doing a half-marathon this fall. It's easy enough - I've run close to that distance already - and it'd be a fun event.


  1. Congratulations for 1 year, and moreover congratulations for knowing how not to get injured.

  2. Injury has become my main worry. I now know I can and will continue indefinitely - but only if I stay mostly injury free. Better to take it easy.


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