Theoretically every extra mile of training per week has diminishing returns. It's a nice theory that gives you a nice logarithmic curve of improvement versus miles gained. Great in theory, but I think that there are points where your 10-20 extra miles per week can give you increasing returns (for a while). Specifically, if you're running around 60 miles a week I think there are surprisingly large benefits to getting up to 80 miles per week.
I found this out by trial and error several times in my early twenties, but never really thought about why that might happen. With the shallow wisdom of being 31 I can look back 8-9 years and see why ... If you get your mileage up to 80 your long run can average 20 miles. Allowing for a bit of a range of ability, that's a 2:15 to 2:45 run. When you're running 60 miles per week, if your long run is in a good proportion to your week it's hard to get above 16 miles, or much over 2 hours. Get your long run out to 20 miles, and you're well into the territory of recruiting fast twitch fibres to keep going. That longer long run, I think, accounts for much of the benefit of getting to 80.
That's 20 miles for the week. I have a friend who jokes that 80 miles is easy, it's a 20 miler and then six 10 mile runs, but if you really want to optimize your 80 miles that's not the best way to do it if actual real life (work, family, the long arm of the law) let you mix it up some more. With 80 miles you are not staring at the more imposing face of 10 miles on your recovery days, so you can have two six mile days for recovery if you choose. That gets us to 32, which leaves 48 miles over 4 runs. Throw in a 13 and 15 mile day (perhaps intervals with long warmup and cooldown, and a long tempo run), and there's just two days left for moderate paced 10 mile runs. There's your 80 miles, with no doubles (singles can be easier to schedule) plenty of recovery, three quality days, and two moderate days for aerobic development.
If you can get the extra 10, 20, 30 ... miles per week that's great. Do that. But I find that the extra benefits from going to 100 from 80 are somewhat smaller than the benefits of going from 60 to 80. You may wonder, how easy does the jump from 60 to 80 feel? Even at the time I remember being surprised at how manageable it was to move up from 60 to 80 over a couple of months. The point is that at 60 miles per week you're doing more than pottering round for health and fitness. Few people run that much without some competitive desire, and for a reasonably small amount of extra time I think there are surprising benefits to be add in getting the mileage up to the magic 80.
Posted by eroberts at August 7, 2006 12:49 PM