At around half past six on a gray Thursday morning, a fleet of garbage trucks begins pouring forth from headquarters, merging onto a congested highway before scattering across the northern part of the city. In one, riding shotgun, is Fernando Beserra, dressed in his blaze orange trash collector's uniform, ready for another day.

When his crew arrives at a quiet street in Sao Paulo's Penha neighborhood, Beserra and two other collectors hop out of the truck, pull on their gloves and set off at a trot toward the morning's first garbage bags, mounded on the sidewalk. They fling them in the truck and hustle off to the next pile -- bend, lift, heave, run, repeat. They'll probably run between eight and 10 miles, all in a day's work for a Brazilian trash collector.

"If they don't run, they won't finish their work," said Cristian Manzale, operations supervisor for the company's northern unit.

In Beserra's case, if he doesn't run, he won't have time to run some more. In his spare time, Beserra is a competitive runner whose grueling workday is often merely his warmup. Training by himself another three or four days per week, Beserra puts in another 50 or so miles of running. "I'm used to it," said Beserra, 33, a slight, soft-spoken man who's been at this six days a week for the past seven years. "It's not that bad anymore."

Beserra is a member of a distinctly Brazilian corps of long-distance runners who use trash collecting as a springboard to running careers. The most accomplished is Solonei Rocha da Silva, who is among the elite international competitors who earned invitations to Monday's Boston Marathon. A top-20 finish at the world championships last August in Beijing also secured da Silva a spot on the Brazilian Olympic team; he will race the marathon at the Summer Games in Rio de Janeiro in August.

Like most Brazilian boys, da Silva grew up playing soccer. He didn't run a race of any kind until he was in his early twenties, and he was so sore after the first, a two-miler, that it was two years until he tried again. In his second race, a 10k, he did respectably enough to win a modest cash prize.

Around this time, while he was also still a raw, developing runner, da Silva started working as a trash collector in the small town of Penapolis in upstate Sao Paulo. His main motivation was simply earning a bit more than he had previously working on truck suspensions. Da Silva ran if and when he could squeeze it in.

"I don't know how many [miles a week] I ran then," da Silva, 33, wrote in an email. "I only trained when I felt like I wasn't so tired I would compromise my work routine, because that's how I put bread on the table then!"

Nevertheless, between his day job and his moonlighting as a serious athlete, da Silva's running career progressed rapidly. At the end of 2009, after about two years as a professional trash-collecting runner, he became a professional runner in the conventional sense. The next year, he won his first big city marathon, in Porto Alegre, Brazil, in 2 hours 15 minutes 45 seconds.

His personal best is 2:11:32, set at the Padua Marathon in 2011.

Being a trash-collector "helped me have the stamina that I have today, as well as the grit and willpower," continued da Silva, writing from his high-altitude training base in Paipa, Colombia, where he was preparing for Boston.

Beserra works for Loga, a company contracted to collect trash in the northern and western half of Sao Paulo. To meet the refuse-disposal needs of some 7 million people, the company employs more than 1,000 trash collectors who gather an average of 142,000 metric tons of garbage a month, generally at a run. Individual routes generally run between 20 and 25 miles, though collectors don't cover the entire distance on foot.

"This isn't for anyone. The job is very tough," Manzale said. Starting salaries for trash collectors run 1,260 reals -- about $350 at the current exchange rate.

Before becoming a trash collector, Beserra was an aspiring but undisciplined runner who struggled to train consistently. He noticed city trash collectors running every day and thought the job would force him into a routine. He's since gone on to record personal bests of 31 minutes 25 seconds in the 10k and 2:33:13 for the marathon -- not world-class times, but ones that would make nearly every other serious runner on the planet proud. Beserra is also an accomplished trail runner and ultra marathoner with an impressive string of top finishes throughout Brazil.

Beserra echoed da Silva's comments about the demands of high-speed trash collecting helping develop the mental fortitude required of any successful distance runner. The end is always the hardest, said Beserra. That goes for his daily shifts as well as the home stretch of a marathon. He's run about 30 marathons and has never dropped out. You don't quit picking up trash because you're tired, nor do you stop racing.

In their own ways, Beserra and da Silva are chasing success in the dogged, lonely manner so familiar to distance runners. Both are proud to have built successful running careers in such an unusual, arduous foundation -- the oft-maligned task of making sure whatever the rest of us drop carelessly in the garbage can doesn't remain underfoot.

"It's a job that's very important in any country," said da Silva. "In Brazil, unfortunately, we don't really place much value, in terms of money or importance, on those workers who do such an important job."

Beserra said he feels valued by the people whose garbage he comes running by to collect. Sometimes they bump into each other at races. Sometimes they see him on the news. They smile, or wave, or say hello before Beserra goes running off again, and it's a big part, he said, of the deep satisfaction he now finds with the state of his dual running careers -- be it scampering after a garbage truck or bearing down on the finish line.

"I'm proud and then some," he said.

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