The Slow Run

This is from Hal Higdon.  I like what he has to say regarding long marathon training runs.  It answers my questions on why I should slow down ....

Run Slow: I know this is tough for you. You want to go out on those long runs and BLAST! Don't! Normally I recommend that runners do their long runs anywhere from 45 to 90 seconds per mile or more slower than their marathon pace. This is very important, particularly for advanced runners who do speedwork during the week. Listen to what the Coach is about to tell you! The physiological benefits kick in around 90-120 minutes, no matter how fast you run. You'll burn a few calories and trigger glycogen regenesis, teaching your muscles to conserve fuel. Running too fast defeats this purpose and may unnecessarily tear down your muscles, compromising not only your midweek workouts, but the following week's long run. Save your fast running for the marathon itself. There are plenty of days during the rest of the week, when you can run fast. So simply do your long runs at a comfortable pace, one that allows you to converse with your training partners, at least during the beginning of the run. Which brings up my next point.

3/1 Training: Toward the end of the run, if you're still feeling fresh, you may want to pick up the pace and finish somewhat faster. This will convert your long run into what I call a 3/1 Run. That means you run the first three-fourths of your long run (say the first 12 miles of a 16-miler) at an easy pace, then do the final one-fourth (4 miles of a 16-miler) at a somewhat faster pace--though still not race pace. This 3/1 strategy is advised for only the most experienced runners--viewers like you--and I don't recommend you do it more than once out of every three weekends. In other words: first weekend, easy run; second weekend, 3/1 Run; third weekend, step back to a shorter distance. My philosophy is that it's better to run too slow during long runs, than too fast. The important point is that you cover the prescribed distance; how fast you cover it doesn't matter. Note: You will only be able to accelerate into a 3/1 Run if you run in control during the "3" portion of the workout. In other words: slow.