Coach Martin brought up a good topic; both for A.T.'s and coaches alike. The longer the foot remains on the ground, the more things can go wrong. I believe there are 2 components to getting off the ground faster. The first is strength, the second is neuromuscular coordination. Whenever I talk about strength training for runners, I always go back to an old NSCA article from August of '95 (can't seem to locate it through the NSCA article search, sorry):
The coach put his girl's cross country team through a dumbbell weight training routine. Nothing fancy, Some of the exercises were specific to running, others were not. They had maintanance workouts two days per week in season. The results: The times of every athlete on the team improved. Of course a lot has changed in the past 15 years, but the point remains the same. That is, the right kind of strength training helps bone density and resists gravity from smashing the body like an accordion with every step. Every (high school) athlete should be able to do a single leg squat to at least 90 degrees without the torso leaning forward and hold it for at least 30 seconds without motion. Every athlete should be able to give you at least 15 good pushups (girls included) without technique breaking down. Every athlete should be able to jump out at least a meter and stick their landing without any wiggling. Every athlete should be able to lunge 3/4 their height for 30s with the knee remaining over the ankle.
Frans Bosch turned me on the neuromuscular component of running. At ground contact, the knee of the trail leg should be passing the weightbearing leg. This is important in locking up the front side and propelling it off the ground; minimizing ground contact. At GAIN this year we had the opportunity to have him put us though many of the drills in his book/DVD. Running with a jump rope is one of the best drills you can do to help clear out mechanical issues that contribute to a long ground contact. If you paw the ground, if your trail leg is lollygagging behind you; the rope will stop you.