well running 20 min intervals and then 20 miles or whatever long distance is are 2 totally different critters.
do you really want me to go into the science beind it? i am tried and havent been at my desk for almost 2 weeks because i have been at heath and fitness conventions and shit.
but if you really really really want me to, i will tell you all about why your friend is losing water and muscle mass when he runs long distance vs burning fat and building lean skeletal muscle when he runs intervals.
but really, im tired, and would rather think about drinking beer in 54 min