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Analyzing 4 million race records from 250 marathons, data scientist and runner Barry Smyth was looking for a way around or over a particular barrier to a smooth and fast race. He was looking to understand why runners “hit the wall,” also known as bonking, and thus, how to avoid it.
Author of the new research published in the journal PLOS ONE in May of this year, Smyth became interested in the concept of hitting the wall when he started running himself. “It seemed to be this big scary phenomenon that really had the potential to ruin a race, and yet I could not find much about it in terms of how it impacted people,” he says.
Smyth is a professor of computer science at University College Dublin. For the analysis, he used race pacing data to take a deeper dive into understanding the parameters under which runners hit the wall.
Before digging any deeper, what does it really mean to “hit the wall?”
For the purpose of Smyth’s analysis, he identified the wall when runners would slow their pace in the late stages of the marathon. But the real definition is a little wider reaching.
“It’s going to look different for different people, and it’s really individual’s internal definition of the wall that really matters,” says Matthew Buman, associate professor at the College of Health Solutions at Arizona State University. Buman also has an interest in what makes recreational runners successful, and has studied the hitting the wall phenomenon in the past.
In Buman’s research surveyed runners identified some of the main characteristics of late-marathon bonking which included: generalized fatigue, unintentionally slowing pace, desire to walk, and a renegotiation of goals (shifting from a goal finish time to just finishing, for example).
Or to get more technical: “Many people have defined it from a physiological standpoint as, hitting the wall is when you run out of glycogen stores,” says Buman.
Who Is Most Likely to Hit the Wall?
In Smyth’s analysis, he found several standout characteristics among runners who were hitting the wall and the degree at which it was happening.
One of the biggest takeaways was in the difference between male and female runners. He found that men were more likely to slow late in the race, likely due to riskier pacing strategies. Despite that difference, how men and women hit the wall was largely the same. “There are some differences in the duration and slowdown, but none as significant as the difference in likelihood,” he says.
Smyth estimates that the cost comes out somewhere to the tune of 31.5 minutes added for male runners and over 33 minutes added for female runners who hit the wall.
Even though women might be less likely to hit the wall, and thus not necessarily adding those 30-plus minutes to their race time, safe pacing might not be playing in their favor either. “Male pacing does seem to be riskier, so they slow more late in the race and suffer a finish-time cost as a result,” says Smyth. But it’s also possible that women are racing too conservatively: “Even though they are avoiding hitting the wall, they are also not achieving their best finish times. They finish the race with something left in the tank.”
Pacing differences between men and women have been studied before, including this study that Smyth authored in 2018. According to a RunRepeat study, women are 18 percent better at running an even pace than men. Data was taken from six marathons—Boston, Berlin, Chicago, London, New York, and Paris—from 2009 to 2019, and found that almost 92 percent of the participants ran the first half of the marathon faster than the second.
Interestingly, Smyth’s data also revealed that runners were more likely to hit the wall in races before or after hitting a personal best. “It seems reasonable to me that runners are more likely to be chasing a new PB in the races before or after achieving their PB, and this may lead them to push themselves harder than they might otherwise, which increases the risk of pacing problems and hitting the wall,” explains Smyth.
Questions Smyth still has that every marathoner and coach probably would also like to know: Are there features in training that make a runner more likely that they will hit the wall? Can early race pacing be used to predict late-race slowing? Are there safe pacing plans that could help a runner achieve a realistic race-time goal without hitting the wall?
He hopes with the advent of Big Data, exercise researchers can study problems from a different angle and answer these question. “Most of the classical studies have involved laboratory-based assessments of elite or competitive runners, for example, but have said little about the majority of recreational runners,” he says. “By analyzing the data that is available, there is much to be learned about recreational runners.”
What You Can Do Now to Avoid and Beat the Wall
Though we can’t always pinpoint when or why a runner bonks, coaches do have tools that can help you have a more successful race execution.
Jenni Nettik with Mercuria Running notes five key building blocks to focus on in training to have a better race-day experience:
- Practice nutrition strategy on all long runs throughout a training cycle.
- Be consistent with training day in and day out throughout training, and prioritize long runs if something has to give.
- Work weekly on mental techniques for working through hard moments in races.
- Visualize the speed workouts as the final six miles of a marathon, and get comfortable with being uncomfortable.
- Practice pacing long runs, finishing every other long run at race pace effort. Mixing progression runs into training to get really familiar with what different paces feel like in the body.
If you’re in mile 20 and you feel yourself fading: Coach Nettik recommends that runners eat some carbohydrates and drink an electrolyte drink to help them get over the wall. “It’ll take a little time for the body to process the carbs, but the sooner you can get fuel to your brain and muscles, the better you’ll feel.”
This kind of bonking is absolutely physical, but it’s also psychological (or bio-psycho-social, as Buman calls it), which is why Nettik also works on mental strategies with her runners. She recommends tapping into mantras, visualizations, and mindfulness to push through the fatigue. “Reflecting back on challenging training runs like tempos, intervals, or long runs can help keep in perspective the discomfort and remind a runner that challenge is only temporary,” she says.
Buman also notes that it is helpful for recreational runners to practice dissociative thinking to work through the wall. “Research has shown that in a recreational runners—it’s not true for elite runners—essentially thinking about something other than the race tends to allow individuals to kind of work through the situation,” he says.