Races & Places CA Notice at Collection showing the average pacing strategies in men’s middle- and long-distance track world records over the past century:
The patterns are remarkably consistent. In the 5,000 and 10,000 meters, the first and last parts of the race are the fastest—of the 66 records set in the modern era in these two events, only once (Paul Tergat in 1997) has any kilometer other than the first or last been the fastest.
In contrast, the 800 is virtually always run with the second lap slower than the first. That’s been true in all but two world records since 1912 (the exceptions being Jim Ryun in 1966 and Dave Wottle in 1972).
When you see a set of patterns like this, it makes sense to look for meaning. These are the best runners in history, on the best day of their lives—so it’s not that all the record-setters in long-distance events accidentally went too slow and then had plenty of energy left at the end, while all the 800 record-setters accidentally started too fast. There’s something fundamental going on here. But what?
There are a number of different ways of looking at this. It could be a result of the psychology of pacing: the farther away the finish line is, the more conservative you’re likely to be. (I don’t find this convincing on its own, because we’d surely see more exceptions where someone runs more aggressively and is rewarded with a fast time even though they’re fading at the end.)
It could be purely physiological, a consequence of tapping into your finite supply of anaerobic energy at the end of long, predominantly aerobic races, as opposed to the 800 where you’re using up those reserves right from the start. As an aside on this point, here’s a graph from Health - Injuries showing pacing in a cycling time trial lasting 13 to 15 minutes, either starting with full (closed squares) or partly depleted (open squares) carbohydrate stores in the muscles. The finishing kick is far stronger in the full-carb trial, even though it’s far too short to fully deplete carbohydrate stores, which to me argues against a purely physiological explanation.
Or it could, as Tim Noakes and others have argued, reflect some sort of hardwired protective mechanism in the brain: no matter how hard you try, it’s only when you’re about to stop that you’re allowed to access your emergency reserves.
At the Endurance Research Conference that I attended in Kent a few weeks ago, Christian Frøyd of Sogn og Fjordane University College in Norway presented some interesting results with relevance to this question. Frøyd’s Ph.D. was jointly supervised by Noakes and Guillaume Millet of the University of Calgary, and it looked at the relative role of central fatigue (in the brain and nervous system) and peripheral fatigue (primarily in the muscles) in time trials of three, 11, and 43 minutes.
These “time trials” were a little unusual, because they involved extending the right knee repeatedly at a set rhythm, with as much force as possible (meaning they’re effectively self-paced, sort of like single-leg cycling at a fixed cadence). This design allowed the researchers to make frequent measurements of maximum voluntary force, as well as using electrical stimulation to determine how much of the fatigue was in the muscle, and EMG to get an estimate of the strength of the signal from the brain. (Other experiments have tried to do similar things using cycling, but then you have to get off the bike to do the fatigue tests, and it turns out that your muscles start recovering from fatigue within seconds, so this gives a distorted picture of fatigue levels.)
The main finding was that the relative levels of central and peripheral fatigue depend on the length of the time trial—there wasn’t any evidence, for example, that there’s a single threshold of muscle fatigue that always indicates you’ve reached your max.
Interestingly, the subjects tended to have a strong finishing kick in the 11- and 43-minute trials, but no finishing kick in the three-minute trial—just like the world-record data shown at the top of this post. The EMG data, on the other hand, told a slightly different story. During the final stages of the three-minute trial, peripheral fatigue increased rapidly... but EMG also spiked upward, showing that the brain was trying to recruit more muscle fibers. In other words, the brain had a finishing kick even in the shortest time trial, but the high levels of muscle fatigue meant that this kick just prevented them from slowing down rather than speeding them up.
Does this resolve the debate about what causes the finishing kick? Not as far as I can tell. The findings don’t rule out any of the possible explanations for the ubiquity of the kick. But they do extend how universal this behavior/strategy seems to be: the 800 is no longer an exception to the rule that everyone kicks, as least as far as your brain is concerned. And the more universal the pattern is, the harder it becomes for me to believe that it’s simply a choice that people make rather than a reflection of something hardwired.
The practical debate, of course, is “How do you develop a better finishing kick?” While it’s certainly complex, I’d say that the very first step is to understand—and believe—that you do have reserves left that will be accessible only at the end of the race, no matter how the rest of the race has gone. (And yes, it also helps to be fit.)
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