This is an interesting thread. I have read each and every post and find myself posting!
Not sure if the insanity workout is for me, hoping someone in a similar position to me maybe able to answer that.
Last year I ran 12 marathons (including a couple of 30 mile ultras). Each one had its own challenge, such as the weather or undulation. However I completed the set with December being my fastest time (3:35). So believe I am somewhere in the middle of the pecking order when I comes to running. The training schedule has me running up to 50 miles per week.
I currently also go to the gym for strength and core work, focusing on back, chest and shoulder muscles. I deviate from heavy weights, low reps to low weights, high reps on alternative weeks. However generally I usually work out not with a schedule and attend 2-3 times a week in during the week in the evenings.
For the gym I use personal trainer that helps break up my gym sessions into more intense sessions once a week which is catered towards improving technique and speed for running. Lunges, squats, press-ups etc. I am usually a sweaty, shaking mess afterwards.
Would there be anyone in a similar boat who could say insanity has worked for them? This year I am looking for speed in my marathons. I want to head towards a sub-3hour (I know I am dreaming, but maybe with 1 year of training) and looking to build speed through cross-training?