In writing about some of my recent 10K races, I have talked about the fact that often runners go out too fast and then slow down in the later stages of the race. This is no big shocker. Even seems to know that people go out too fast in races, whether they do anything to avoid being sucked into that is another question. There’s something else that seems to happens to runners in the 10K that may be a little unique to this distance. I’ll call it the “10K pace dip”, because I think that sort of sums up what happens.
Unlike hitting the wall in the marathon, where runners are reduced to walking and also unlike a gradual slowing down of the pace that you see in 5Ks or other races, the “dip” looks more like this. Along about mile 4 or 5, there is a sudden and very pronounced dip in the pace of about 15-30 seconds a mile. Having seen runners experience this, its an involuntary drop in pace at that — meaning that they know the pace is dropping off quickly, but they can’t seem to do anything about it.
In my last two 10Ks, the way I’ve noticed this is I’ll be running along, maybe a few paces behind a runner and then all of a sudden — bang — I’m not only passing them, but I’m on top of them and then past them in a stretch of 50 yards. It’s like they’ve immediately gone from one pace to another. But they don’t die off completely either, because they end up finishing within say 30 to 45 seconds behind me.
So this is a little different than the slow drop off of pace that we normal see when people go out too fast and peter out over the course of a few miles. Here the pace drop is pronounced and sudden.
What’s Causing “The Dip”?
Let’s think about the 10K in the context of our speed training. If we’re looking at 4-5 miles through a 10K then the runner has been pushing at a hard intensity for at least 30 minutes or more depending on their speed. This may not sound like a long time for the typical marathon runner, but put this in context with other workouts that the runner might be doing. Interval workouts may last in their entirety over 30 minutes, but generally speaking the intervals themselves are not that long. And even tempo runs for most runners — which would be run at slightly slower than 10K — would usually only be in the range of 20-30 minutes for most runners. What this means is that the duration of this intense effort is actually longer than what these runners may be doing in their workouts.
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