boris johnson fight me bitchI'm not sure if I've mentioned this before, but there's a pretty good formula for determining how fast you could run some distance (with appropriate training) given how fast you can run some other distance:
t2 = t1*((d2/d1)^1.06)
where d2 is distance you want to run, d1 is a distance you already ran, t1 is the time you ran it in, and t2 is the time you should expect.
It's remarkably accurate (for me at least) for distances over 2-3 km.
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