A - Well, as a matter of fact, I am a HUGE proponent of weight (strength) training for runners - well all athletes for that matter (see a previous post re: weight training and arms here), in order to:
1) increase the muscle strength/weight ratio thereby decreasing the ever present risk of injury;
2) be used as a form of active massage/rehab., using relatively lighter weights and higher reps;
3) provide a springboard for developing power and ultimately basic speed (you can't bench press 200 lb. quickly unless you can at least bench press 200 lb. In the first place. Duh ).
As for advice - hmmmm. Ok, here's a tip.
Over the years whenever I've worked out at various clubs, I naturally watch the folks going through their routines. And it's remarkable how many fail to include exercises that specifically address the lower back (erector spinae anatomically speaking) by the incorporation of back raises, dead lifts, etc. in their routines.
Now friends, how can you be talking about strengthening your core, and not be addressing the "other" side of your torso?
Need convincing? Put your hands on your lower back while standing, and shift your weight from one foot to the other, and just thrill to the dramatic contractions of those lower back muscles. Oh ya ! Obviously they are going to be seriously involved upon each concussive landing!
Of course, there are several optional exercises you can employ to strengthen the lower back. My favourite for specifically targeting this area is the 45-degree back extension. The images below are taken from the great website, ExRx.net, and an animation showing the action can be seen here.
If you haven't already been doing back raises, you will likely be astounded at how quickly fatigue sets in. Trust me, I know this from personal experience. The number of reps you will be capable of vs. the number of bent-knee situps on a slant board will be far less ! I recall being fatigued by 10 reps. when I first started....Ridiculous!
But, with regular inclusion it is amazing how dramatically the rep. number will increase dramatically, even to the point you will be holding weight plates close to your chest to add to the resistance. It will be a whole new world !
And, I know for myself how strengthening this area reduces low back aches. (this is assuming you have no medical condition where such exercises may not be considered appropriate)
So for those of my running clients who are able to fit strength training at a gym in to their busy schedules, I heartily recommend they do so, and that they include exercises aimed at strengthening their lower backs.
Back It Up !