A.M.Pondered the issue of stride length. Recalled that one British coach suggested that stride length is affected by the range of motion in the hip extension and the strength of the plantar flexors, particularly the soleus. Remembered that back in 2008 Jeff and I measured the circumference of the calf and the quad with the following results:
Lower shin, thinnest part - Jeff 7.5, me 8.375. Calf, the widest part,
flexed - both 14.5 inches. Quad, widest part, flexed - me 21 inches,
Jeff - 20 inches. So Jeff was definitely ahead on the flexed calf to shin size, and flexed calf to flexed quad size ratio. In other words, his calf appear to be stronger relative to body size.
Also recalled that in numerous studies running economy was correlated with the ballistic power of the ankle joint.
Combining all of the above - if you want to run efficiently you need to learn how to use your calves. For me that is not easy. My calves do not want to work. But I decided to start focusing on using the calves more.
Ran 4 miles first, did a 0.5 pickup in 2:40 to catch up to Sarah, then ran with her for 1.5 miles. Then took Benjamin and Joseph for a mile, then dropped Joseph off and did a workout with Benjamin. Focused on the calf action. We did 4x100 17.4, 17.4, 16.6, 17.1. Then 3x200 33.4, 34.0, the last one I challenged Benjamin to race me. I got 30.5, he did 31.4. That is the fastest I've gone in a 200 this year, and that is also Benjamin's PR.
Then dropped Benjamin off, and went for some more miles. Did a pickup over an odd distance - 2100 meters, this was the longest good stretch of the trail, in 7:01, one second slower than 5:20 average.
Ran 0.25 with Jacob in 2:30 - new record since the broken leg.
Jenny and Julia did 1.5. I got total of 12 miles.