As a running coach of recreational runners (read non-elite athletes), I see a wide variety of abilities, talents, training methods, and training mistakes.
One of the most common training mistakes I see is when a runner makes every workout "kinda hard."
Frequently, I'll see someone completing a long run at a pace that keeps their breathing slightly elevated so they have to catch their breath to keep a conversation going. This is a medium-hard running pace, pretty equivalent to marathon pace or close to it.
Then, I'll see the same person at a track workout, and again, they are working kinda hard, but not hard enough. The result? The runner never gets faster.
Why?
Two reasons. One, the runner never gets the numerous beneficial adaptations that are caused by running at a slow, easy pace. Two, the runner never runs the tempo workouts and track workouts hard enough to get faster because her body is tired from always running kinda hard.
In reality, a good training schedule has about 80% of running volume at an "easy" pace and 20% of running volume at a hard effort.
What does this look like? Well, if you are running 30 miles per week, then about 24 of those miles should be run at an easy pace, while the other 6 miles are hard and fast. What does this mean for most recreational runners? The long run needs to be run at an easy, slow pace. In fact, professional runners almost exclusively run their long runs at a slow, easy pace.
I know it is tempting to think, "Well, if I just run this long run faster, then I will get faster." But, actually, running at an easy pace not only allows you to do your hard workouts better, but easy paced running changes your body in a lot of beneficial ways.
Think of it like this. If you are studying for a test, then you have two options. You can cram hard a couple of times before the test or you can study frequently and consistently. As a high school teacher, I can tell you that the latter is a much more effective method than the former.
Completing a long run at an "easy" pace, running your tempo runs at the proper fast pace, and completing your track workouts at a very hard pace is a much better formula than doing everything at "kinda hard" levels.
Research demonstrates that the best results tend to come from a training routine that has very easy days and very hard days and few days in between. This is called polarized training. What does this mean?
Generally, it means that runs, which are not tempo runs or interval workouts, should be run at an easy, slow pace. Easy is relative, so I'll give you some guidelines to help you figure it out.
What is an "Easy" Running Pace or Speed?
An easy pace feels too easy. You should be able to have a long conversating with someone and never feel like you need to catch your breath. You should be able to recite a Shakespearean monologue without much effort. You should probably wonder to yourself at some point during the run, "Am I going too slow?" If you ask that question then you are, in fact, going at the right speed.
Easy pace is, generally, 1 to 2 minutes SLOWER than your goal marathon pace. So, if you're goal marathon pace is 8:30/mile then your easy run pace is between 9:30 and 10:30. If your goal marathon pace is 9:00/mile, then you should not be running faster than 10:00/mile unless you are doing a tempo run or a track or hill workout.
Consider this fact: Many elite Kenyan marathoners will frequently go out for runs at 8, 9, or 10 minutes per mile. That may not seem odd to mere mortals like us, but consider the fact that their marathon pace is faster than 5 minutes per mile. So their easy or recovery days sometimes consist for running at a pace that is up to 5 minutes per mile SLOWER than their marathon pace.
The Benefits of Slow, Easy Running
What good is running that slow, you ask? Well, here is a long list of the physiological benefits of slow, easy running.
1) More Capillaries: Your running muscles lengthen existing or create new capillary beds that deliver more oxygen to your muscles. More oxygen means faster running.
2) Mitochondria: Remember the "energy plants" of cells from biology class? Well, easy running tells your mitochondria to produce more aerobic enzymes to help you produce more energy. More aerobic enzymes mean faster running.
3) Running Efficiency: The more you run, the better your brain and central nervous system become at running. Running is a skill, just like catching a football. The more you do it, the better you get at it.
4) A Stronger & More Powerful Heart: Easy running increases stroke volume and cardiac output, which does not happen at faster running speeds.
(Source: The Science of Running by Steve Magness)
Consequences of Going Too Hard Too Often
Make sure you are not doing your long runs too fast. Your long runs should be done at an easy pace. Doing them too hard will cause a couple problems.
1) You will be more prone to injury.
2) You will wear down your body.
3) You won't be able to run your hard workouts fast enough.
When I am training for a marathon, I will only do one or two long, hard runs. I usually do them in races. For example, for this last marathon, 5 weeks out I did a hard 20-mile race. and 3 weeks out I did a half-marathon at faster than goal marathon pace. But the rest of my long runs were done at or around 7:30/mile, which turned out to be 1 minute slower than my marathon pace. Next time, I will go even slower during my long runs so I can do my weekly workouts harder.
If you want to read more about polarized training, then here is a good blog post on the subject by renowned Triathlete coach Joel Friel. However, a caveat. Exercise physiology research is frequently unrealistic, in the sense that the experiment does not reflect how people actually train for endurance sports. Oftentimes, the experimenters are not competitive athletes or the restriction within the lab require that the experiment be done in certain, non-real-world ways. What does this mean? It means that great information can be gleaned from these experiments, but training should not directly mimic the experiments. If you have more questions, then feel free to ask me.
-Brendan Ward, brend.m.ward@gmail.com