Self-quarantine can be an opportunity to make the most of a sedentary day. Learn a new language online. Take up knitting. Get through that stack of books you have been meaning to read.
Or you can leave the cocoon of your couch and join the worldwide tribe of lockdown runners who are trying to adapt to the challenges of confinement.
Social distancing has forced runners to innovate, whether they are casual hobbyists releasing the pent-up steam of cabin fever or elite athletes trying to maintain their mileage.
Improvised tracks are being carved out in living rooms, and on rooftops and balconies. Indoor treadmills are getting hammered. Distances are being clocked vertically in apartment building stairwells.
James Campbell, a former javelin athlete in England, saw opportunity in the 21-foot stretch of grass and gravel in his backyard. As his mind ricocheted with boredom from being cooped up inside his Cheltenham home last month, a question dawned.
“What was the most stupid thing I can do to create a little bit of excitement for myself?” Mr. Campbell recalled asking himself. “I will run a marathon in my garden.”
And so he did. Mr. Campbell put down duct tape to mark a circuit of laps. He set up drinks and snacks on tables, rigged equipment for an online watch party and created a link for donations to support the National Health Service’s coronavirus efforts.
At just after 9 a.m. on April 1, Mr. Campbell, 32, set off. He jogged, looped and circled. Sometimes he trudged backward, or in a figure-eight pattern. His neighbors watched from the fence. His online fans urged him on. A GPS device tracked his progress.
“I just kept going,” he said.
Five hours and five minutes later, he had put in 26.2 miles.
Mr. Campbell said he had not been a serious runner before his feat, but that he kept fit in a gym and had been working out at home before his backyard marathon.
The lockdown rules dictated by the coronavirus pandemic mean many runners are getting their fix by logging their miles in tight circles, like a hamster on a wheel, to avoid contact. Runs once displayed as long courses on Strava now appear as thick dots or zigzags, reflecting routes dictated by space constraints.
Some runners eschewing the outdoors have bought rowing machines, stationary bicycles or step-climbing equipment, anything to stay in motion while not going anywhere.
Tammy Whyte, a running coach based in Washington, D.C., said she was giving online fitness classes to her athletes. “There are a lot of ways to get your heart rate up inside,” she said.
“Some runners are using running as a way to relieve stress right now,” she said. “You can do little laps in a balcony or stairs or a little yard.”
Fears of infection and the need for social distancing have also spurred new rules of etiquette, especially as concerns grow over how much of a distance from other runners is considered safe.
Some runners are wearing a Buff, a versatile tubular garment popular in the sport, to cover their mouth and nose. Others wear masks and gloves, and think twice about where and when to clear their throats or spit during long runs.
And others are practicing the “coronavirus swerve,” giving people a wide berth on streets, sidewalks and trails.
Michael Wardian, 45, an elite ultramarathon runner who lives in Arlington, Va., said he no longer goes on group runs or meets with a personal trainer as part of his routine.
“It has completely changed,” he said.
His strenuous off-road runs have been transformed. “Even my secret hidden trials are overrun with people now, because everyone has found the outside,” Mr. Wardian said. “Places where I would go for solitude are not as conducive for that.”
Rob Tidwell, 49, of King George, Va., and his family have also reassessed the tracts of wilderness they once plied, giving up their forest and Shenandoah mountain routes and sticking instead to their neighborhood, which has become the more remote spot.
“People are flocking to the parks and trails are getting closed,” he said. “The last time we went out of our neighborhood to the park, it was packed with people.”
For Anna Carlsson, 34, a long distance runner, the opposite is true. Her favorite wilderness spots have been abandoned as visitors stopped traveling to her village of Abisko, Sweden, near the Arctic Circle.
Ms. Carlsson said she would normally not be putting in miles near Abisko at this time of year. But with marathons canceled, she saw no need to trek south for her usual spring training.
Instead, she is making do with the slippery mountain tracks carved out by snowmobiles, or sprinting across the frozen surface of Lake Tornetrask.
“A lot of tourists are usually here at this time of year because of the northern lights,” she said. “But right now it is super quiet.”
But Ms. Carlsson and others are still finding a way to be competitive, as races crop up online to replace the isolation-averse contests on public streets, where spectators press against barricades and runners move in dense packs.
Ms. Carlsson was one of more than 2,413 people in 56 countries who took part in a virtual race, the Quarantine Backyard Ultra, this month, distant in geography but united online from their living rooms, backyards and neighborhood streets.
In Dubai, a Russian man ran around his living room for 20 hours. A Canadian, Matt Shepard, wanted to avoid frostbite so he ran part of the race inside a coffee shop in Valleyview, Alberta, that had been closed because of the coronavirus pandemic. Greg Armstrong, of Lebanon, Tenn., had to pause on his treadmill at one point to remove a snake from his house.
The goal was to complete 4.17 miles at any pace in each of 63 consecutive hours of running, or a total of just over 262 miles. The overall winner would be “the last person standing,” said Stephanie Gillis-Paulgaard, an organizer.
At 9 a.m. on April 4, Mr. Wardian, the runner from Virginia, set off on a loop of less than a half-mile around his house. As he passed again and again, his neighbors rang bells and cheered from a distance.
It was a close finish. On April 6 at 11:31 p.m., Mr. Wardian won after a Czech competitor on a treadmill, Radek Brunner, was disqualified on a technicality after he began his 63rd hour too late after the starting bell, Ms. Gillis-Paulgaard said.
“At the end it was down to me and one incredible athlete,” Mr. Wardian said in a video message on Twitter. “Radek was pushing me beyond anything I think both of us had ever done in the past.”
The prize? A plaque bearing a gold-painted toilet roll, a comic nod to one of the items most hoarded by pandemic shoppers.