Would Hypothetical Man run a faster mile in 12 months if he ran 4 miles as fast as he could on 100 different occasions or 2 miles as fast as he could on 200 different occasions?
Hypothetical Man might get injured with either training program, but I’d tend to lean toward the latter as producing the best results. The pace you can hold for 4 miles is enough slower than the pace you can hold for 2 miles that it would seem less specific to racing 1 mile.
(I’m basing my answer on the training principle of specificity, which is that you have to train for the event you’re racing. If you run nothing but long slow distance, for instance, you probably won’t do as well in the mile as if you ran short, fast workouts. Similarly, you don’t do a lot of 400m repeats if you’re training for the marathon.)
Thanks Adam. Of course, I vary my runs throughout the week/month, but there always seems to be a two or three day window where I’m busy but got a little time for either one four mile run or two shorter runs on different days. This usually occurs in tax season and tax season is, thankfully, officially over!