EXTREMEendurance

Assistant Professor Linda Trinh tests her limits in the Moab Desert

Linda Trinh had, like many a traveller before her, just passed through the gorgeous desert and red-rock canyons of Moab, Utah, and now she was heading into the mountains. The difference was, Trinh wasn’t cruising in some Jeep. She was on foot.

The race director of this, the Moab 240 ultramarathon, had diabolically designed the course to hit the La Sal Range at around the 200-mile mark. Trinh had been running, pretty much continuously, for more than three days. The lush fall colours barely registered. She was just watching her Hoka Challenger ATR shoes coming up underneath her, again and again.

The trail was narrow and the mountainside steep. Suddenly Trinh heard a voice behind her. It was the pace runner for another competitor. She’d noticed Trinh wobbling and implored her to stop and take a dirt nap. “Thanks, I’ll be okay,” Trinh replied genially. Trinh was exhausted, but she has also learned to distrust those warnings from her brain. (Your brain is conservative; it’ll tell you to quit when you actually still have gas in the tank.) But the other runner kept insisting. “And finally, I was like, you know what, she’s probably right,” Trinh says. “So I stopped and slept. It was the best 10-minute nap of my life.”

Ultramarathoning may be one of the defining practices of Homo Sapiens, arising from our ancestors’ quest for meat on the veldt. But it’s a pretty weird thing to be doing in 2023. Trinh, who is an assistant professor of exercise and cancer survivorship in the Faculty, came to the sport 10 years ago, while completing her doctorate at the University of Alberta. She’d been training for her first marathon when a group of ultradistance trail runners got her hooked on stronger stuff. (Following a bunch of strangers deep into a rural park in the middle of winter: what could go wrong?) Trinh was beguiled by the questing element of it, the frontier courage required: you can’t really be found unless you’ve first been lost.

Any race longer than 50 km is considered an ultramarathon. The Moab 240 is more than six times that distance. Think of Toronto to Ottawa, with a mountain range in between. Trinh knocked it off in 109 hours and change.

But back at that 200-mile mark in Moab, she was getting pretty beaten up. “You’re a different person when you finish a race like that than when you start,” Trinh says. Indeed, you’d be hard-pressed to find a sport that changes athletes more –psychologically and physiologically.

In 1980, when he was a budding scientist, KPE Professor of Exercise Physiology Ira Jacobs led a study that deepened understanding of the adaptations the body makes to extreme, chronic physical activity. The test subject was a Dutch athlete who was ranked among the top-10 ultramarathoners in the world at the time.

Jacobs et al. wondered: just what is different about an ultra athlete? They took biopsies from the fat of the subject’s abdomen and the muscles of his legs and conducted an intravenous fat-tolerance test. Each revealed a different surprise.

Carbohydrates and fat are the main fuel for our muscles during exercise. Carbs are stored in our liver and muscles as glycogen and are released to the blood as glucose. But the gas tank of carbs is depleted to almost empty within an hour or two of moderately high intensity exercise. “Fortunately, we have plenty of fuel for long distances at much lower intensity, and that’s fat,” says Daniel Moore, associate professor of muscle physiology at KPE. “This was an adaptation we needed for our genes to survive.” The success of an ultra athlete depends on how efficiently they’re able to metabolize that fat, via an enzyme called lipoprotein lipase.

Jacobs and his colleagues infused fat into a vein and monitored how quickly it was whisked out of the bloodstream and into the furnace. “The clinicians had never seen infused fat removed so quickly from anyone,” Jacobs says. “This guy had the highest lipoprotein lipase activity we’d ever measured in our lab. So then the question is, is he born, or is he trained? And I can’t answer that.” (No baseline measurements had been taken for this athlete before he began endurance racing. And unfortunately he didn’t have an identical twin who could have been the couch-potato control.)

“I suspect it’s a combination of both. But,” says Jacobs, “we got a hint from the muscle biopsies we did in his leg.”

The two primary types of human muscle are the so-called fast-twitch and slowtwitch fibers. Fast-twitch fibers mostly burn sugars to generate explosive power, and slow-twitch effectively burn fat for endurance. Each of us has a mixture of both types. But when Jacobs tested the little plug of tissue he’d pulled from the Dutch athlete’s thigh, he found 100 per cent slow-twitch. The result was so astonishing that Jacobs thought he’d made a mistake. So he repeated the test. And got the same result. “Eventually I called over my labmate – a more senior PhD student – to check my work.” It used to be thought that the muscle you were born with was what you got. No one dreamed we could change our muscle any more than a turkey breast could change from white meat to dark meat en route to the dinner table. Jacobs et al. contributed to our new understanding of how adaptable skeletal muscle (and to an extent the human body itself) actually is.

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There are a lot of cool things about ultradistance racing. For example, it’s one of the relatively few sports where gender really doesn’t matter, performance-wise. The physiological advantages of males shrink as the distance lengthens. The winning times of the top men and the top women converge. (Many consider Courtney Dauwalter of Golden, CO, the world’s best ultradistance runner, period.) An unappreciated factor, surely, is that women know the sleepless pain cave intimately. It’s called childbirth.

But besting men – or even trying to best her own time – is not really part of the motivational mix for Trinh. It’s about the buzz of the mutually supporting community, a camaraderie that belies the stereotype of the loneliness of the long-distance runner.

And Trinh finds something of that same vibe in a different community: the classroom. “My philosophy around ultra running is a window into my teaching philosophy,” she says. “I tell my students, ‘The mind you enter with when you start the course is going to be a different mind than you have at the end of the course. The journey itself will change you.’ Break the task into chunks; for now just make it to the next rest stop. There will be physical and psychological hurdles ahead. You can manage them if you prepare for them.’”

You can imagine such words buoying the spirits of, say, a doctoral student who’s in the dissertation pain cave. “You say to yourself, I’ve got blisters on my blisters. But I have to deal with it, because I’ve got 100 miles left to go.” — Bruce Grierson