Why do distance running training programs tell you to do long runs so slowly?

Question

I'm trying to improve my times in the half marathon and the marathon, so I've been reading a lot of training plans for races at those distances. One thing I've noticed is that most of these programs tell you to do your long training runs quite slowly, often recommending 60-90 seconds per mile slower than your target race pace. Why is that? That is, it seems like if I want to become a faster runner at a certain distance, the best way to train would be to run that distance, quickly. Yet most plans instruct you to do your long runs slowly, and to build speed in separate, shorter workouts. I can see the benefit of doing shorter workouts at a faster pace, but I don't see how doing my long runs at 60 seconds/mile slower than my goal pace is going to help me as much as doing them at as close to my goal pace as I can handle. Isn't that how most training works?

So why is that? Is it just to keep my legs fresh for other workouts? (If so, then couldn't I run faster if I know I'm going to have a day or two of rest following my long run due to my schedule?) And is there empirical evidence to support that these long, slow runs train athletes better than faster runs of the same distance? Or is it just unquestioned coaching orthodoxy?

Edit: There are some good answers below, but I haven't accepted any of them because thus far no one has been able to point to any scientific studies. They may not exist; they often don't for this type of thing (it's almost baffling how little hard, scientific evidence we have for so many of our most deeply held beliefs regarding fitness and exercise). That's what I'm hoping to find, at any rate.

Answer 1

The Furman Institute of Running and Scientific Training (FIRST) put out a good book called Run Less Run Faster. You can find a lot of information contained in the book at the original article in Runner's World.

Basically, the FIRST program outlines 3 types of training runs. The three FIRST workouts are a long run, a tempo run, and a speed workout that are designed to improve your endurance, lactate-threshold running pace, and leg speed.

What this points to is that long runs improve endurance, not speed. Upping the intensity would add extra stress for little gain. FIRST has done multiple studies, and has seen great results. Whether the studies are completely scientific, I cannot say.

Answer 2

I've been to the FIRST running camp (two years when I was in high school). They do have a lot of good information; however, I have anecdotal experience that will help you in particular with the half marathon or marathon.

I would avoid any sorts of interval or short speedwork stuff. Weldon Johnson (co-founder of Letsrun) dropped his 10,000m time to 28:06 off of slower, longer, and more frequent runs than what he had been previously doing.

Here is a great article by his coach John Kellogg: http://www.letsrun.com/jkspeaks4.php

I would say if you want to drastically improve your half-marathon time (as opposed to running for recreation) you will need to:

1. Run twice a day. Historically, this has proven to be the optimal training frequency.
2. Run as much mileage as you can handle. Build up slowly -- over a period of months and years.
3. Add a long tempo run each week, or 2 of them if you can handle the stress. It should be about 8-9 miles and about 85% of the effort of your half-marathon race pace. To make it more interesting, you can start at a slower pace and work down to faster than your HM pace for the last few miles.
4. Recovery. Increasing your training will inevitably make you feel very tired at first. Don't worry -- this is normal and you will get used to it. However, sleep is VERY important at this point because your body does not build fitness during exercise, but afterwards while you recover. Make sure you're taking in appropriate nutrients as well.

In my opinion, the "long run" each week is highly overrated. I could run a marathon or even a 50k faster than most of the population based on my college training for the 8k (one person on my team actually decided to run a well-known marathon just for the heck of it and won), which proves you don't need to throw in a single high mileage run to become fast.

One day with disproportionate mileage compared to the rest of your week is only going to get you injured or tire you out. Yes, there are physiological benefits that come with running longer, but you will reach this automatically as your day-to-day mileage steadily increases.

Also be careful with the long, slow distance (LSD) trap. Don't purposefully trudge through your runs at a pace that feels uncomfortably slow or unnatural. There's a famous quote -- I think by Sebastian Coe -- that long, slow distance produces long, slow runners. The point of the slow runs is mainly to recover from your workouts. Many people make the mistake of running their hard runs too easily and their easy runs too hard. As another example, a different person on my team would run 14 miles at 5:20 pace followed by two days at 8:30 to 9:00 minute pace. This pace is slower than most neighborhood joggers. He PR'd every single race that season and moved to the front of the team.

So I think that's about it. I would recommend finding someone to train with as well (and maybe you already do), because as you increase your mileage you will find it much more enjoyable with a training partner.

Answer 3

The simple reason for a LSD is to get you comfortable with being on your feet for a long period of time. The reason for doing LSD runs at a much slower pace is because running at pace is very demanding on your body, especially over several hours. It's all about preventing injury.

Answer 4

I've always found that if I run faster, I can't run as far. It's as simple as that for me. If I want to run a long distance, I can't run as fast. Eventually, as I either run that distance more, or increase my distance even more past that, I can run it faster.

Also, I'm always surprised by my times on race day. There's a lot more motivation to keep you going a little harder then.

If you find that your long runs are too easy and you think you should be pushing harder, you may consider upping your target time. Maybe you underestimated your ability!

Answer 5

Continuing on from the answer from Nick, I think that it is a strong case for learning the principals of training.

I'll expand; If you train at 100% all of the time you will burn out within 6 months, this is because you are pushing your body to the limit all of the time. That is not good for you as our bodies were not designed to do this.

I think you should research periodisation as well. At certain times of the year, you want to focus more on different things. Eg, winter is for putting in the miles, summer is sharpening up for the races etc. This will vary from sport to sport and disciplines within sport.

Example:

I am a 100/200m sprinter and we would following something similar to this and bare in mind that it is specific to sprinting:

Sept -> End/Jan

Putting in the miles, so lots of over distance training like 3/400's (we need the base endurance to increase the speed later on). This is typically about the 80% effort mark.

Feb -> End/April

In these few months, we would up the pace to 90% for about half of our sessions keeping the rest at 80% effort. One key term we use here is lactate stacking, so short recoveries in our interval training.

Eg.

2 (sets) x 6 (reps per set) x 150m (distance) with each run in 20/21 seconds off of 45 second recoveries and 5-8 min set recovery. We would then do something like 10 x 40m at near maximal effort to push our bodies even harder.

Mar -> July

This is usually race season, so the intensity gets turned up to 90% effort + every session. Loads of 100% speed work.

Remember it's all specific to your distance. Research periodisation and different training types (interval,fartlek etc).

Answer 6

I've just reviewed Tim Noakes, Lore of Running, 4th ed (2001) - specifically the section on Base Training (pp303-317). This book is very well regarded as the authority on the science of running. I can find nothing in that section which refers to a peer-reviewed study. All the advice is the collated advice from some very well regarded coaches - e.g. Arthur Lydiard.

I will note that Lydiard had his athletes running long but fairly fast and on a hilly course.

If you really want Dr Noakes does respond to email.