Wednesday, July 8, 2009

Finding the Tempo

When I first got into triathlon—well before I got into marathon—I'd read blogs and find myself baffled at the frequent references to "tempo runs." It's a curious term; I half thought you ran to a beat. I did some research, of course, and gained a bit of an understanding of the term, but it became clear that like a lot of things in life it was something I needed to experience to really get. Amazingly, it took me until today to do that. Six marathons, several half-marathons, countless 10Ks, 5Ks and ultras ... and finally I did a tempo run.

Here's the low-down on tempo runs, beginning with the key fact: Tempo runs are all about improving endurance by raising your lactate threshold. Lactate threshold? Well, as explained by Pete Pfitzinger in Advanced Marathoning:
Lactacte is produced by your muscles and is used by your muscles, heart, liver, and kidneys. The lactate concentration in your blood represents a balance between lactate production and consumption.... As you increase your effort from resting to walking to easy running, your rates of lactate production and consumption increase, and your blood lactate concentration stays relatively constant. When you run harder than your lactate threshold, however, your lactate clearance can no longer keep up with lactate production.
From there Pfitz starts talking about ions and stuff, but the takeaway is that in this situation, pushed past lactate threshold, clearance no longer keeping up with production, your muscles tie up and you slow down.

So you can see the benefit of improving your lactate threshold. And the way to accomplish that is to “run at your current lactate-threshold pace or a few seconds per mile faster,” to quote Pfitzinger again (you’d think I’d use his training plan, all the quoting of him I do). At that pace, lactate is beginning to build up in your blood, so your body is stimulated to improve your ability to clear it—to make physiological adaptations. Pfitzinger says this pace is around your 15K pace, maybe up to half marathon. FIRST says it’s 15-45 seconds slower than 5K race pace, which is pretty much the same neighborhood where Pfitz has you playing.

My first ever real live tempo run was 5 miles @ 6:45 pace. I did an easy run over to Laurelhurst Park (just shy of a mile and a half from home). I headed there because the roads and sidewalks on the outer perimeter of the park—not in the park itself—are lightly trafficed and a loop is almost exactly a mile, which helps to maintain a sense of my pacing just by where I am. Still, of course, I wear my Garmin, and I get data. Such as:

You can see I was pretty good about my pacing. A little quick for the final two miles, which is shocking because I was in more than a little pain by then. Check that: I was hurtin’! I think there’s still some lingering fatigue from IMCDA, plus Monday’s track work really put me through the wringer. I was creaky Wednesday morning and when I got up to tempo speed could tell my legs weren’t as fresh as I would have liked. That's something I'll have to pay attention to, since a core principle of the FIRST method is that the relative paucity of running gives you time to recover and be ready to tackle the intensity of the workouts. I need to make sure I get fully recovered soon.

As I did after my track repeats, I didn’t bother doing a cool-down run; I walked home from Laurelhurst, regaining my equanimity and pondering this very new and exciting running adventure.

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