Let me preface my comments by saying that for many runners – runners of all ages – there needs to be a build up of the long run to a level that they will maintain for months. This post pertains to that long run, not the preceding long runs where the athlete is building their volume.
I firmly believe that to fully develop the aerobic system you have to run a weekly long run. And that run should not be slow. Doesn’t have to be a “race from the gun” type long run (though I’ve done my fair share of those) but at the least it should be a progression of running that takes the athlete through faster paces as the run progresses. Or, say you’re running 17 miles. You run the first six really easy, then the next four still talking, then you run five at a pace where you could talk but you probably aren’t talking, and then you squeeze it down just a bit more for those final two miles.
That said, when you do a hard long run, you should be able to say, “I could have run one, two or even three miles longer at that pace. Those extra miles would have been really hard – maybe even felt like a race – but I could have done it.”
Don’t finish a hard long run fully spent. A solid long run takes many athletes longer to recovery from than threshold workouts or some track workouts. If you follow the Sunday long run then Tuesday workout schedule you may not be recovered for Tuesday if you crushed Sunday.
Final thought. Be patient with your development on long runs. Good athletes who are running fast times may not be able to run great long runs. Eventually the long runs will get faster, but if you’re not at a level where you can run your long runs very fast, don’t worry…just be able to say “I could have run one, two or even two miles farther at that pace.”
Run your long runs hard, but run them controlled.