Training begins today for my fall marathoning season. I'm using the Pfitzinger-Douglas Advanced Marathoning 18-week program, peaking at 55 miles, though I'll probably add a few miles here and there for recovery.
LT runs are lactate threshold, or tempo, runs, done at 15K to half marathon pace
MP runs are marathon pace runs.
10x100 are typically striders, controlled 'sprints' to work on leg turnover
Trackwork (5x600, etc) are at 5K race pace and happen later in the program