Re: Short races and long run during a marathon training
I think one of the things if you are going to be serious about training for an racing marathons is that you just have to accept that you are not going to be able to race very frequently or with a taper at other distances. Those things have to fit in as part of your marathon training plan and goal.
I am not in favor of racing 5ks in training for marathons, it is just too short, especially if you are using it in place of a long run. I would say you could do it if you were willing to put in a 15 mile long run (you said it was a cutback week) on Saturday and then race on Sunday--even then I don't think the cost/benefit is worth it, but you definitely cannot substitute a race of that distance (even with a good warm-up and cool-down) without compromising your goal.
A 10k is more in the range, but again I could not justify that in place of a long run, but only as a supplement to it. It is a good racing distance to build some fitness and gives you a good idea of where you are at (a 5k is just too far from marathon distance to be any good for this). I personally try to race on Saturday and run long on Sunday, but I usually find shorter races are on Saturday, not Sunday around me.
I do not think you risk injury if you add on to a 10k with a good warm-up and cool-down, but you should run the additional mileage pretty slow. Again, try to get in about 15 total.
Southern Man
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