Billat calls it polarized in that 2001 paper, and at the end of that sentence credits a 1981 paper on elite marathon runners. Iām digging the flashback to 70s running 
craze. Everything old is new again!
Joking aside, was watching a womens biathlon event last night and everyone crossed the finish line and collapsed. Those short XC events are legendary in my mind for showing just how hard you need to train in order to push the body to its absolute limit. I salute all the bad asses of this world that train that hard (and easy)!!! Ride on my friends, and excuse me while I psych 
myself up to tackle a polarized build