PORTLAND – Long-distance running helped Bernd Heinrich develop and refine his theories about evolutionary traits that make it possible for some humans to essentially run faster prey such as antelopes into the ground.

The 62-year-old University of Vermont biology professor was not, of course, chasing any real antelopes on Saturday in Brunswick when he set out to defend his championship in the Maine Track Club’s 50-mile race.

But Heinrich relied on what he regards as a distinctive combination of skills that he maintains have made humans well-suited to running long distances, even outrunning faster animals such as antelopes that possess high aerobic capacity but lack the endurance of some humans.

The ability to sweat makes it possible for humans to run hour after hour without overheating and being forced to stop in order to cool down. Another key factor is their capacity to focus their minds beyond immediate pain and imagine rewards such as hunting down prey or winning a medal.

“The ultimate weapon of the long-distance runner is the mind,” Heinrich said. “When it gets painful, you have to think about the rewards up ahead. You have to keep that dream in your mind.”

With a few exceptions, such as migratory birds, other animals are unable to look toward those kinds of long-range goals and stick with them, he said.

Heinrich’s theories were spelled out last year in his book, “Racing the Antelope: What Animals Can Teach Us About Running and Life.” He looks at a range of animals – from camels and antelopes to bumblebees and frogs – to gain insights that carry over into running.

“Running has given me a lot of my perspective,” he said. “A lot of my research is related to exercise and endurance, temperature regulation, metabolic factors, what kind of fuel to burn.”

By writing the book, which was reprinted this year in paperback under the title “Why We Run,” Heinrich managed to combine his academic interests and the sport he has pursued for most of his life.

A native of Germany who moved to the United States as a child, Heinrich ran track in high school and college. Aside from a few years when he set running aside, he continued to race or “just jog for the fun of it.”

His competitive streak remains intact. As a marathon runner, he said, he recorded a personal best of 2 hours, 22 minutes in the late 1970s in California and had a couple of top-50 finishes at Boston.

Heinrich was content with marathons until he took note of the fact that he was passing a lot of runners toward the end. He figured that his own physiological characteristics made him a better candidate for longer runs.

Since that decision, he has joined the ranks of the ultramarathoners, a tiny segment of the running community for whom 26 miles is not nearly enough.

At one time, Heinrich held the U.S. records for 100 miles and 100 kilometers. He also held the distance record for a 24-hour run, completing more than 157 miles during that period.

Saturday’s race was a low-key event, drawing 22 runners. Heinrich had planned to pace himself at eight-minute miles and try to break his 50-mile record of 6 hours, 39 minutes. But he opted during the race to run the 50-kilometer (31-mile) event instead, finishing first in just under 4 hours 5 minutes, more than an hour ahead of the runner-up.

Heinrich’s training for the race peaked at 100 miles a week before scaling back to between 20 and 30 miles during the week of the race.

In 1981, during his record-setting 100-kilometer race in which he averaged just over 6:38 per mile, Heinrich tanked up on cranberry juice at various intervals. On Saturday, he fueled his engine with Gatorade and ice cream.

Heinrich, who has a retreat in western Maine, plans to keep on running as long as he can. He was sidelined a few years ago with knee injuries and arthritis, but the knee got better on its own and he was back on the road.

Despite his ultrarunning records, Heinrich doesn’t see his performance as anything beyond what most people could achieve if they abandoned the couch potato lifestyle that comes with sitting in an office all day and not having to chase anything down.

“People need exercise,” he said. “If we don’t have it, we’re in trouble.”