Lessons from 10 marathons run in 10 days on a lab treadmill


In November 2017, Sharon Gayter, a 54-year-old British ultrarunner, ran ten marathons in ten days on a treadmill, with a combined time of 43 hours 51 minutes 39 seconds, beating the former Guinness World Record by more than two hours. What’s significant about Gayter’s feat now, besides being an impressive mark that still stands, is that she ran all ten marathons in the sports science lab at Teesside University in Middlesbrough. , in England, enabling exercise physiologist Nicolas Berger to compile mountains of information. He presented these results in a recent article published in the International Journal of Environmental Research and Public Health.

The data in the article includes details on sleep, hydration, and calories burned and consumed by Gayter during each 24-hour cycle; their heart rate and perceived effort during the race; and ten-day changes in his body weight, fat, and muscle. And while the data reveals some interesting insights into how her body responded to the challenge, Berger cautions that we can’t consider her specific strategies universally applicable. “Other runners probably shouldn’t use Sharon’s example as a model for their own ultra efforts,” he says. “Sharon is quite unique, particularly in her recovery and consistency.” Still, Gayter’s racing data and experience suggests some principles for runners box to apply. Here are the highlights.

Slow down to save carbs

Gayter is an accomplished ultrarunner who has completed over 200 ultras including Badwater, Marathon des Sables and many other high profile races. Her experience was evident in the Teesside lab, as she completed all ten marathons between 4:21:21 and 4:24:38.an average of 4:23:09 per marathon. “It went exactly as I planned,” she says. “I thought there would be less than ten minutes between my fastest and slowest times.”

Gayter had hoped to consume a steady supply of fuel as she ran. According to many endurance nutritionists, marathon runners should aim to consume 120-240 calories (or more) per hour. Gayter tried, but his stomach refused to cooperate.

“We had drinks, candies, sandwiches, smoothies and protein shakes on hand, but she became so nauseous she was unable to take them,” Berger says.

Despite having a wide variety of fuels at hand, Gayter was able to ingest very little during his marathons. (Photo: Courtesy of Nicolas Berger)

As a result, Gayter choked on just 180 calories on day one and only 126 calories on day two. After that, she only consumed water and several handfuls of grapes in her last eight marathons, or about 46 calories per marathon.

Another rider might have rightly panicked at the low fuel supply. However, Gayter had been there before and knew she could go on. “I rarely take carb drinks in my ultras, because of the nausea issue,” she admits. “I thought they might be OK in that short term, but it just didn’t work out.”

Instead, she ran smartly, at a pace that seemed sustainable. She estimates that she could have run a single hard marathon in about 3 hours 30 minutes at the time, more than 50 minutes faster than her ten-marathon average. “Her marathon pace was slow, so she didn’t need quick energy from carbs,” says Berger. He calculates that Gayter burned fat for 67% of the calories she needed versus just 33% of the carbs.

“Sharon is used to running long distances on little to no carbs, relying on fat stores for energy,” says Berger. “Other runners who consume as little during the race as she would probably see their performance drop after three hours.”

Even with the pace controlled, Gayter’s heart rate increased by five beats per minute by the third hour of each marathon, and another five beats by the fourth hour. Likewise, his perceived exertion increased by about 10% during the third and fourth hours. Berger says the increase in heart rate and perceived exertion was both fairly minor and expected. “Running for more than three hours becomes uncomfortable and there’s not much we can do about it,” he says. “Perhaps with more energy and salt or electrolyte intake, Sharon would have experienced less upward drift in heart rate and exertion.”

Restock quickly

Berger says Gayter often tries to put on a few pounds before a big event because she knows she’s going to lose weight during the race. During her ten-day quest, however, she had to rely on strict post-race fueling strategies to keep up.

Immediately after completing each marathon, Gayter turned to her replacement drink, a milk-based shake that included whey protein, colostrum powder and a banana. “That drink was probably my most important recovery strategy,” she says. She started each day with an early breakfast, then had a snack of soup and bread an hour before running. In the evening, she ate meat, roast potatoes, gravy and mixed vegetables, followed by apple crumble with double cream. Before going to bed, she drank chocolate milk.

In total, Gayter burned an average of 3,305 calories per day, including 2,030 per marathon. She could only consume 2,036 calories a day. This means she lost weight (5.7 pounds), body fat (4.2 pounds) and muscle (0.9 pounds) over the ten days.

“It’s hard to recoup what you spend running four and a half hours a day,” says Berger. “Given that Sharon consumed so little during her runs, I think she did incredibly well.”

Cultivate consistency and focus

Berger considers a consistent day-to-day structure essential to Gayter’s success. “One thing that turned out to be crucial was that she had a daily plan, but she remained flexible as needed,” says Berger. “When you follow the same successful procedures, you can exercise more control over anything that could go wrong.

To reduce stress, each day’s marathon intentionally started late, at 11 a.m., allowing Gayter to get optimal sleep and time for lunch and snacks before the race. She slept an average of 8 hours 20 minutes per night, with the longest night’s sleep – 9 hours 47 minutes – on the seventh day and the shortest – 6 hours 50 minutes – on the fourth day.

Sharon Gayter gets her legs massaged
Gayter’s daily post-race routine included a recovery drink and a massage. (Photo: Courtesy of Nicolas Berger)

Gayter has been particularly consistent in sticking to his ten-day post-marathon recovery plan. “She was sipping her recovery drink even as I was doing post-race testing, and then she got a massage,” Berger says.

Nor did she try to distract herself from the long daily efforts. During her nearly 44 hours of running on the treadmill, she didn’t need to watch TV or listen to music or audiobooks. “I’m mentally strong and can focus on the job at hand,” she says. “Music and people talking to me are a distraction. My mind works with numbers. I focused mainly on my pace and my milestones, like every kilometer or ten kilometres.

How many more days could Gayter have continued to run marathons at the same pace? It’s impossible to say, but she and Berger made the same estimate – five more days. “I didn’t want to go any faster because I would have risked more nausea and maybe missed the record,” she said. “But I had plenty in reserve.”

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