Easy Running is by far the most important aspect in all of distance running, from the 500m up to the marathon. Nothing is even close to being more important; not tempo runs/steady state runs, not progression runs, not hills, not fartleks, not intervals, NOTHING.
Easy Running is the foundation of distance running. It is a known fact that easy running helps bud new capillaries. It is a known fact that easy running increases the stroke volume of your heart. It is a known fact that easy running helps build aerobic enzymes involved in the citric acid cycle (also known as the Krebs Cycle). This makes aerobic metabolism more efficient and delays the need for anaerobic metabolism, and thus running hurts less and you can run faster. So in other words, easy running increases your endurance. This is HUGE in distance running, people. Furthermore, easy running increases the number of mitochondria which means your body can produce more adenosine triphosphate (ATP).
Folks, anyone who says easy running is not important is WRONG. Folks, anyone who says that you're running too slow is WRONG. In fact, you can NEVER run too slow. Run 10 minute miles if you feel like it, and you'll reap all of the amazing benefits I mentioned above and you will become so much better of a runner.
I'm going to tell you guys a little story. Going into my first year of cross country (sometimes abbreviated as XC), I did NO workouts in the summer. All I did was easy running. I ran 8-10 miles a day VERY easy. As in very easy, I am talking about 9-10 minute miles. At an early season practice, our coach had us doing 3 x 1 mile with a rest in between (not sure what). My first mile was 5:27!!!!!!!! That might not seem significant, but this was my FIRST year of cross country. And furthermore, nobody on the team was even close to me. It was me against myself. Me pushing myself.
This goes to show how important easy running is. Off of ONLY easy running, I was able to run a very fast mile repeat in my FIRST year of cross country.
Now, imagine had i incorporated some speed work in. Imagine I had done amazing speed workouts like, but not limited to: 3 x 200m, 2 x 300m, 400m, 2 x 300m, 3 x 200m on 90 sec rest, 600m-500m-400m-300m-200m then back up on 2 min rest, straight 200m reps like Paarlauf style, 300m reps, 400m reps.
Folks, had I done this, we may have been looking at a 4:40 mile IN practice IN the beginning of the season. That's scary guys.
Now, I very much appreciate the ones who have read to this point. I mean that very sincerely. Now, let's get to the main point finally. What I am trying to say is that EASY RUNNING is by far the most important aspect of distance running because of its AEROBIC benefits. Forget tempo runs, progression runs, fartleks, and hills. None of them pose the same AEROBIC benefits as easy running.
Aside from the majority of your training being easy running, you need 200-600m reps like I discussed above to buildup some lactic acid. Actually, fun fact, it is really the accumulation of H+ ions that cause your legs to burn when you run. Lactate is the other ion but the hydrogen ions are what lower the pH in your muscles and causes the burning feeling. OUCH right? So anyways, yes. You need to run 200-600m reps to become comfortable (oxymoron, eh? LOL) running in an anaerobic state or with acid buildup. Run until your legs FALL OFF. Don't worry about pace, just like you don't on easy days.
So yeah, go for an easy run. Go as slow as need be. Don't let anyone tell you otherwise. The benefits go on and on, even beyond the ones I mentioned. Look at and come to admire the beautiful planet we live on as you're cruising along. I promise you'll thank me. Oh, and don't forget to accompany that with short 200-600m reps TWICE a week.
Easy Running (AEROBIC) + 200m-600m reps (ANAEROBIC) = Success
I want ya'll to be successful so I thought I would pass this along. Peace out, and enjoy some PLAYOFF FOOTBALL!!!!!