Sunday, January 13

Is flat really fast?

We've all seen it in a race descriptions: "flat and fast" course.

Sure, on a 5k or even a 10k, a pancake flat course ignites PR dreams. But is flat really "fast" on longer distance races?

After many years of running and racing, I'm beginning to question the flat-is-fast logic. Before moving to Florida, I had never run a truly "flat" course.

Look at a topo map of San Diego. Compare it with Pensacola. You'll quickly understand what I mean. If that's not sufficient, here's a visual comparison... Yes, in that first photo I'm "hiking" in San Diego using a fixed rope to get down a rock ledge. And, yes, I'm scared sh**less in that photo.
Not flat: Four mile hike to Three Sisters Waterfall in San Diego. 
The second photo shows a favorite northwest Florida trail which has, maybe, 10 feet of elevation change along the entire route - typical of the topography here.
Flat: Four mile run along the Blackwater Heritage Trail near Pensacola
I expected that flat Gulf Coast topography would work in my racing favor, even if the weather didn't.

However, my burning quads and aching calves told a different story (especially after the Holiday Half Marathon in Point Clear).

What I'm finding is that my legs are TIRED after racing flat courses. My hunch is that hills recruit slightly different minor muscle groups and thus legs (my legs, at least) are less fatigued after a long run on gently rolling hills than they are after an entirely flat 13.1.

So I did a little research.

Which race courses are the fastest?

Runner's World compiled a list of the most competitive marathon courses. Not surprisingly, the list focuses on flat or net-downhill routes.

Of course, the statistician in me thinks: Who cares what proportion of the field BQs? Maybe only BQ runners sign up for this race. You're saying flat races have fast fields, but you're not controlling for WHO is running!*

So... fast runners gravitate toward flat courses.


Does that mean flatter is faster? Or easier?

Even within the flat-is-fast list, the details give a clue that my hunch - that flat isn't necessarily fast - isn't so harebrained after all: 
"The course [at the Baystate Marathon] is flat... with just enough rolling terrain (10 to 15 feet up and down) to lessen muscle fatigue."
And of the California International Marathon...
"Race officials describe the gradual downhill route as 'biomechanically friendly,' meaning that for every gentle uphill, there's an equally gentle, and longer, downhill."
Ahh... muscle fatigue!

If you've ever seen a muscle-targeting chart next to an elliptical machine, you know that when we use an elliptical, we recruit different muscle groups at different levels of incline.
Image source
Running follows a similar pattern.

Arizona Central's health section notes:
"When you run a consistently flat terrain, the same muscles work for all 26.2 miles. A varying terrain shifts the muscle emphasis from the quads to the hamstrings as you race up and down hills. A flat course never allows the muscles to shift their workload and rest. As a result, you may fatigue sooner and find recovery harder."
And Pete Pfitzinger writes:
"... pancake flat marathon uses your muscles in exactly the same way over the same range of motion for thousands of strides. This lack of variety enhances fatigue as your hamstrings and calf muscles and quadriceps repeat the same cycle over and over again. To prepare optimally for a flat marathon, you should do most of your long runs over similarly flat terrain."

Well, Mr. Pfitzinger, I train on flat courses (this is coastal Florida, after all) but I think I still prefer a few rolling hills in my races.

So, flat might not be so fast after all.

Bring on the hills!!!

What do you prefer? Flat, rolling hills, or steep-as-they-come courses?

*With respect to the "who is running" issue, I will note that I've run the San Diego marathon. It is not a flat course, yet San Diego has one of the fastest course records in the U.S. And... um... Boston has the fastest U.S. course record (2:03:02). Anyone who's ever seen Heartbreak Hill knows Boston is not a flat course.

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