I first read about SoM this spring and am starting to try it out this summer. I still don't fully understand the physiological benefits to doubling, besides the added mileage. I first thought people doubled just for practical and logistical reasons, and to add mileage easier, but from reading SoM threads there appears to be more to it, however I haven't really seen a clear explanation. Anyone care to share the ideas behind it?
You do doubles to get in 2 stresses per day. Your body releass hormones after each stress.
Some research was done decades ago that demonstrated that training twice a day (in a wide variety of disciplines) was superior to training once: greater training stimulus, better recovery.
[Interestingly, training thrice a day was *not* statistically superior to training twice.]
Different things work for different people, but for most people two training sessions seem to work better than one.
Some people do seem to benefit by adding doubles gradually, say by starting with two or three days of doubles per week and building up from there. In my personal case, I can say that doubling almost daily (after previously doing singles on most days) wasn't difficult at all.
"There is no try, only do."- Yoda
It works, don't ask questions, do SoM if you want to be good.
Some other research was done decades ago in Russia in a scientific experiment. Runners trained 1-6 workouts per day.....they found no better aerob capacity out from the doubles and more workouts.
COACH J.S