Tung Trinh has taught himself to push the grocery cart with one hand — his right.
The Garrison Forest middle school dean refuses to tuck his left hand in his pocket, even when hurrying between campus buildings on bitter days. His left hand must swing freely so the activity-tracking device he wears on his wrist records his steps.
And recording his steps is a bit of an obsession for Trinh, 32. He's among the millions who track their movements with wearable devices, such as a FitBit, a Jawbone, or, in Trinh's case, a Garmin Vivo, which the school doled out to faculty members last year.
It begins innocuously enough, with a New Year's resolution or a competition with workers or friends, but some users find themselves planning their lives around the quest to get more steps. They troop up and down the stairwells, pace through parking garages and march in place to hit their goal — typically 10,000 steps a day. Some competitive souls rack 30,000 steps — or 15 miles — each day.
"If there's a number on it," said Trinh, "I always want to know what it is."
Tracking gadgets were a hit in 2014, with sales approaching $500 million in the 12 months ending in November — more than twice the same period in the previous year, according to the NPD Group, which monitors retail trends. The devices range from $50 to $250, depending on how many features they offer.
A bevy of new trackers were showcased at this month's Consumer Electronics Show in Las Vegas. Some were disguised as pendants and gleamed with Swarovski crystals. Baltimore's own Under Armour unveiled a fitness-tracking app, UA Record, that coordinates with the company's activity-tracking chest strap and other devices. There are gadgets for kids (KidFit), for dogs (Whistle), and even a Kickstarter campaign for a home aquarium tracker. That one is called FishBit.
Baltimore Mayor Stephanie Rawlings-Blake marches in place behind closed doors at City Hall. The mayor said she tries to work in short bursts of exercise throughout the day to hit her goal of 10,000 steps.
She said her friends send encouraging notes using the FitBit's messaging feature. A few send gibes.
"Some of my friends are not so nice and send messages saying, 'I had no idea that as mayor someone carries you around all day,'" she said. "Then the gauntlet's been thrown down and I have to get busy."
Plenty of health-conscious folks have been using smart-phone apps, such as Pacer or Breeze, to monitor steps. The fitness-specific devices hold special appeal for lovers of data and technology and those with a competitive bent.
Trinh, the Garrison Forest dean, felt a mixture of delight and dread when he accepted the activity tracker in September. A few years ago, he had become somewhat fixated on tracking his runs with a similar device, which he eventually decided to sell.
"I had this anxious feeling like, 'Here we go again,'" said Trinh, who logs 10,000-15,000 steps a day.
The devices compile reams of data, which can be accessed through an app, graphed and stored in a spreadsheet. Some track sleep patterns, heart rate and calories consumed.
"I love trying to see the patterns," said Annapolis software developer Leigh Anna Geraghty.
The 48-year-old pores over charts showing how much she tossed and turned at night and how many steps she takes each day.(Mondays are her most active and Tuesdays the most sedentary, for reasons she has yet to understand.)
The worst days are those when she leaves her FitBit at home and loses a day's worth of steps.
"If I forget it one day, it's depressing," she said. "I just lost a whole day's count."
For some, like Mount Washington resident Ryan A.Z. Hill, the devices can become a bit of an obsession.
The competition at her workplace started innocently enough: employees were given FitBits in an effort to boost health and morale.
She now hides her stats from her co-workers until results are tabulated at the end of the month, in an effort to edge out the competition.
One particularly devastating month, Hill wound up in third place, by a measly 147 steps.
"Failure is just 147 steps away," she posted on a note about her desk.
"I feel fit," she said. "But I feel like the FitBit group is turning me into a monster."
University of Maryland physiology professor Espen E. Spangenburg said that 10,000 steps a day is a good goal to for those who want to maintain their weight or lose a few pounds. But those looking to lose significant amounts of weight or reverse years of inactivity will need to do more, he said.
The 10,000 steps goal "doesn't take into account intensity," Spangenburg said. Vigorous exercise and strength training can lead to bigger changes, he said.
For some, the goal might not be getting fit, but simply winning a competition. Blog posts and YouTube videos demonstrate ways to trick the devices, including what appears to be the most popular method — clipping them to a dog's collar.
After an injury kept him from the office fitness challenge, one man built a simple freestanding machine he calls the "FitBit Cheat-O-Matic." It waves the device back and forth all day, creating the illusion that the inventor is in constant motion.
Most users, though, say they would never cheat because it ruins the fun of the competition. And many would not be able to get away with cheating because their chief rival is also their spouse.
Monique Beutel, 43, and her husband, Brad Beutel, 51, goad each other on.
"He loves to get to 10,000 steps before I do," said Beutel, a compliance officer for United Healthcare. Sometimes her husband will catch her eye at a party or a bar and point to his wrist — his signal that he's met his goal.
Many workplaces, like Hill's, give the devices to employees in an effort to get them exercising and improve their health.
At Garrison Forest, teams of teachers and administrators compete for fitness-related prizes, like yoga mats and gym passes.
Lisa Fleck, a middle school guidance counselor, walks around the school's wooded campus with colleagues and goes on runs with neighbors.
If she hasn't met 10,000 steps by evening, she'll march in place in the bathroom while her 6-year-old daughter bathes.
"She says, 'What are you doing, Mommy?'" Fleck said.
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Over at the North Baltimore retirement home Roland Park Place, employees can earn paid time off for taking an average of 120,000 steps a month over a three-month period, said marketing director Bridget Marie Forney.
Roland Park Place's athletic trainers also gave the devices to interested residents, such as retired linguistics professor Anne Wyatt-Brown.
The 75-year-old works out with a trainer three days a week, takes at least five exercise classes each week and swims. And now she takes the stairs to her fourth-floor apartment to boost her step count to about 7,000 per day.
"I used to be lazy and take the elevator," said Wyatt-Brown. "But I take real pleasure in knowing I'm increasing my steps."