There are a few golden rules of running — completely uncontroversial pearls of wisdom that every runner learns early on:
Don’t try anything new on race day.
Avoid sudden increases in mileage.
Never train in worn-out shoes.
Here’s another: Maintain a steady pace in races.
Like most of the sport’s eternal truths, this rule has scientific support. Most recently, an international team of researchers led by Daniel Suter of the University of Zurich analyzed the relationship between pace variations and overall performance among participants in Ultra-Trail du Mont Blanc (UTMB), a 106-mile trail race, between 2008 and 2019. Specifically, Suter’s team looked at 13,829 individual performances over this 11-year (12-race) span, comparing average paces between checkpoints throughout the course against average paces over the full distance.
The results were quite clear. “To conclude,” the researchers reported in the International Journal of Environmental Research and Public Health, “our study supports the hypothesis that constant (even) pacing is the best strategy to achieve a top position in an ultramarathon running event such as the UTMB, regardless of age or sex. Athletes and coaches should, therefore, focus on a constant distribution of work throughout the race.”
The even-pacing rule applies in shorter events as well. For example, in a study published in the International Journal of Exercise Science, Thomas Haney and John Mercer of UNLV compared pacing variability against overall performance in non-elite runners across three tiers of marathon finish times: sub-3:54, 3:54–4:36, and above 4:36. Given that the slowest marathoners can’t slow down as much from their starting pace without stopping altogether, Haney and Mercer expected to find less flux in the third group, but as it turned out, pacing variability increased across all three tiers, with runners in tier one varying their pace by an average of 12.3 to 13.2 percent compared to 15.1–15.9 percent in tier two and 16.8–16.9 percent in tier three.
Harder Than It Sounds
If those numbers seem rather large, you’re right — they are. Although even pacing appears to result in better performance at all distances greater than 1500 meters, far fewer runners succeed in pacing themselves evenly in marathons and ultramarathons. A 2019 study that compared pacing patterns among non-elite runners in marathons and half marathons found significantly less variation at the shorter distance in most age and gender groups. Among men aged 40 to 44, for example, speed varied by 9.4 percent in the half marathon and by 11.8 percent in the marathon.
Of course, “variation” really means slowing down. No runner ever runs at a perfectly consistent pace in any race, but the greater variability of pacing seen at longer distances is accounted for almost entirely by a slowing trend. This pattern has two main causes. The first is fatigue. No runner can sustain any pace forever. Regardless of how fit you are or what initial pace you choose, you will begin to slow down eventually as you tire out. Longer races simply allow more time for fatigue to do its thing, so it’s only to be expected that runners tend to slow down more in these events.
The other major reason runners slow down more in longer races is that, the longer the event, the harder it is for an individual runner to judge the highest speed they can sustain over the full distance without slowing. Like any skill, pacing skill is experience based. It’s much easier to know how fast to run the first 100 meters of a mile than it is to know how fast to run the first mile of a 50-miler because we cover the former distance routinely, the latter seldom, if ever.
Maybe It’s OK to Slow?
In discussions of this sort, it is often taken as a given that even pacing should be the goal for every runner in every race distance. Should it, though? It’s worth noting that even the best ultrarunners tend to lose steam toward the end of successful attempts to break records at extremely long distances. A typical example is Camille Herron’s world record for 100 miles, set at the 2017 Tunnel Hill 100 Mile, where Herron started out averaging under 7:20 per mile, slowed down to around 8:00 per mile, and finished with an average pace of 8:38 per mile. Whenever the preponderance of top performances at a given distance result from positive splits (meaning the second half of the race is slower than the first), it’s sensible to conclude that, for whatever underlying physiological reason, this particular pacing strategy is optimal (as it clearly is at 800 meters, for example, where 24 of the last 26 world record-breaking performances have featured positive splits).
What’s true for the likes of Camille Herron at 100 miles could conceivably be true for less gifted runners at shorter distances such as the marathon. After all, judged by time, a middle- to back-of-the-pack runner’s marathon is equivalent to an elite runner’s ultramarathon. Perhaps, then, it’s okay for us mere mortals to accept a modest loss of speed in the late going of longer races as unavoidable and aim merely to keep this deceleration from getting out of hand.
There’s a fairly strong argument to be made against such resignation, however. Consider Zach Bitter, who managed to avoid tailing off when he broke the men’s world record for 100 miles in 2019, covering the second half of the run more than two minutes faster than the first. And there are middle- to back-of-the-pack runners who do the same in marathons. Case in point: At the 2018 Rehoboth Beach Marathon, Laura Zimmitti reached the halfway mark in 2:22:56 and then picked up her pace slightly, crossing the finish line in a huge PR of 4:42:47.
Bitter and Zimmitti could be the exceptions that prove the rule, of course, but there is some science to suggest otherwise. In a 2017 study, Swiss exercise physiologist Beat Knechtle, one of the world’s leading experts on pacing in running, teamed up with Pantelis Nikolaidis of the Exercise Physiology Laboratory in Attiki, Greece, to analyze pace data from more than 300,000 participants in the New York City Marathon between 2006 and 2016. Among their key findings was that older runners paced themselves more evenly than younger runners with equal finish times.
Now, if the tendency to slow down in longer races were the ineluctable result of a physical limitation, then we might expect to see an even more pronounced slowing pattern in runners who are past their physical prime. In fact, though, we see just the opposite, which suggests that experience and wisdom can enable any runner to buck the natural tendency to slow down over the course of longer races.
Plan and Practice
Still, such runners are the exception — so how do you become a steady pacer? The keys, I believe, are intentionality and practice. Unless you’re a natural-born steady pacer, it is unlikely that you will succeed in completing longer races at a steady pace unless you start them with an explicit intent to do so, as well as a concrete plan. Laura Zimmitti offers a great example of this. “I was determined to break 5 hours,” she told me via Facebook. “I took it on very deliberately. I wore a pace bracelet for a 4:55 finish. I stuck to the pace for the first 13 miles. My plan was to check in at miles 13, 16, 20 and 23. If I felt good, I picked it up a notch. At each juncture I felt great. By mile 16, I was passing people at regular intervals. At 23, I still felt good. I decided that no way would I allow myself to finish feeling good, so I started to run hard enough to feel the pain.”
As for the second key to becoming a steady pacer — practice — it’s worth noting that the 2018 Rehoboth Beach Marathon was Zimmitti’s seventh attempt at 26.2 miles. Her failure to run a steady pace in marathons 1-6 provided the experience she needed to know what sort of pace she could sustain for the whole distance, and also how she should be feeling at different points of a marathon to avoid slowing down.
Hitting the wall in a longer race is not the end of the world, and for many runners, including Zimmitti, it’s an almost unavoidable step in the process of mastering the pacing element of longer events. If you run a marathon with the goal of breaking 4 hours and you maintain the required pace of 9:09 per mile for 21 miles, and then the wheels come off, try starting at 9:15 per mile the next time. Granted, that pace won’t get you below 4 hours, unless you can pull off a solid negative-split second half effort, but it will probably get you to the finish line with even splits and, more importantly, establish a solid tactical foundation to go faster in future events.