Today's training: 12.72 miles, lake loop, 2:07:40 (10:02 min/mi), avg 145 bpm
Today was a day when the stubborn approach worked out. I was pretty convinced that I was going to carry the hamstring pain with me through the marathon anyway and the only question was whether I could run without making it worse. Anyway, I stubbornly did my usual Sunday route around the lake instead of the elliptical at the gym I promised. I added an extra half mile of warm up walking and started running very slowly, mixing in a walk break every 5 minutes or so, which you can see on the graph. After about 4 miles, I mostly ran. Later I got a little conservative and threw in some walking breaks. Although the average was 10:02 min/mi, I was typically around 9:30 or lower when running. There are a few flat places where I'm used to seeing a particular pace and heart rate. I was as good or better than last week at those point, so I was happy about that.
The graph also shows some of the very annoying features of STraM. If it's possible to change the scale for the speed display, I don't know how. As a result, if you ever walk, it skews the whole thing and the region you're interested in is crammed in a fraction of the display. Plus, you can't tell how fast you're going because the number above 10:00 min/mi isn't shown. The scale is non-linear with min/mi, so who know what that is. I switched to mph and it looks like it oscillates around 6.4 mph or 9:22 min/mi, which is what I recall. Early on I was also able to keep my heart rate under 150 at this pace. Since my goal marathon of 4:00 requires a 9:09 min/mi pace I think I'm on track for that.
I got light-headed around 2 hours, which I attribute to the fact it was 2 o'clock and I never ate lunch. (I had a "just plain" Gu and it was pretty tasty.) My heart rate also jumped 5-10 beats. It seems like there's some magical point at around 10-14 miles (depending on the day) where my heart rate just steps up. I'm not sure what it corresponds to (heat, glycogen depletion?), but I can maintain my pace if I just accept the higher heart rate.
Another km-mile conversion datapoint. My watch read 12.79 miles and 20.47 km. 20.47/1.6093 = 12.72 and 20.47/1.6 = 12.79. Again it appears 1.6 km/mi is being used. I think it's "case closed" on the bad conversion factor.
Another km-mile conversion observation. It had always bugged me that the pace on the watch didn't match the total time and distance. Today is an obvious example. 12.8 miles at 10 min/mi takes 2hrs and 8 minutes. I finished in 2:07:40, which is less than 2:08:00 and yet the pace was displayed as 10:02 min/mi. Now I understand why. It appears the correct conversion factor is being used in the min/mi pace calculation but not in the distance calculation. 12.72 miles in 2:07:40 is 10:02 min/mi.
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