"Staying on your toes", unless sprinting is a recipe for lower leg disaster.
Attempting to screw around with one's foot strike, with the very rare exception of under the guidance of a trained coach, is a poor idea.
And studies have shown that for many runners, heel striking (to an extent) is more energy efficient.
The second statement I partly agree with, and would say that any changes in footstrike and gate should be done gradually. While working with a coach is the best idea, it can be done with some old fashioned research and self-training (assuming you get the right information).
There's a huge disparity in the research, but it seems that whatever your natural gait is is how you will be most efficient. I haven't seen any longitudinal experimental studies whereby heel strikers were measured once and then trained to run with a mid-foot beneath COG strike and measured again. Might be interesting, and yet, totally impractical from a research and funding stand point.
McCrew--don't worry: your coach was right. I say the same thing to my sprinters (200's and below). Anything above that is going to require a midfoot to heel strike unless you are looking for destroyed legs. And at any rate, trying to force a footstrike is a dicey proposition.
And carb-loading, while fun, isn't really needed for events under 30k.
Oh. . .and I am running a triathlon in my avatar (I do plenty of marathons though too)
In regards to allowing my shins to heal, does that mean laying off weight lifting exercises such as deads, squats, and lunges? Or just strictly running?
I don't think you'll have a problem with non-triple extension movements, there is minimal plantar/dorsi flexion.