While other kids played Minecraft and watched Nickelodeon, 13-year-old Travis Leatherwood, a Catonsville Middle School student, spent Saturday morning learning how to use the leg press and the elliptical machine.
Five-year-old Taryn Clever was in another gym, smiling while doing sprints and burpees, an explosive variation on squat thrusts reviled by most grown-ups. And 9-year-old Delilah Jeeter was pushing a 100-pound metal sled across a parking lot while her dad watched in awe.
"If there's any exercise that makes you feel like you're going to throw up, this is it," said Jarrod Jeeter, an Ellicott City father of three. "But not for the kids."
The children laugh and cheer, oblivious to the suffering many adults feel during their workouts.
Physical activity for children usually means soccer games and ballet classes. And while these activities remain exercise mainstays for children, more gyms and fitness programs that were designed for adults are being adapted for youthful enthusiasts.
"Increasingly, clubs are looking to provide something for everyone," said Tom Cove, president and CEO of the Sports and Fitness Industry Association. "Functional training — boot camps, CrossFit, ropes, suspension training — is attractive to younger people. Exercises that use your own body weight [are] a trend we're seeing, and some of it is very easy to adapt for kids."
Gyms now routinely have youth classes. Marathons include family fun runs and kids' 5Ks. Yoga studios cater to children from babies to teenagers.
At the Y of Central Maryland, a Fit N Fun program for elementary school students introduces youths to the idea of exercise classes, and a newly revamped Teen Quest class teaches kids ages 11 to 15 to use gym equipment.
"It's self-motivating," said Nancy Deems, an Elkridge mother who enrolled her 15-year-old daughter, Sarah, in Teen Quest. "If she weren't doing this, she'd be the first to tell you that she'd be at home watching 'SpongeBob' or something."
Sarah Deems, a freshman, swims regularly but is trying the Y gym for the first time. "My goal is to get in shape for our family camping trip," she said.
In the past, she'd come to the gym with her mom. But, she said, "I'd sit on the sofa and watch TV."
Some kids, like Travis Leatherwood, who plays baseball, are in the gym to become better athletes.
But Salil Maniktahla, co-owner of Urban Evolution, a parkour and free-running gym in Baltimore that welcomes kids as young as 6, said many are there as an alternative.
"They might have been turned off by team sports," he said. "But when they get into the gym, they're very gung-ho."
Aidan Dexter, an eighth-grader from Ellicott City, used to play soccer but now opts for CrossFit Kids. "I like how it's fun, yet it's still a workout," he said, noting that it's better than gym at school. For one thing, Aidan said, "You don't have to be quiet."
For some, the classes offer relief from the pressure that comes with competitive sports, dance or cheerleading, said Maura Roth-Gormley, who teaches Teen Girl Yoga Squad at the Baltimore Yoga Village.
"This is a more collaborative environment," she said.
Children are particularly well-suited to yoga, which helps teach concentration and breathing techniques.
"They're naturally more flexible and adventurous," said Roth-Gormley. Watching kids gleefully do back-bends, wheel poses and frog jumps, she said, "You just think, 'Ah, to be young again.'"
But even in yoga — considered gentler than many fitness classes — Roth-Gormley avoids poses that could create head or neck pressure. "It's better safe than sorry," she said.
Many fitness programs need to be modified for children's growing bodies, experts say.
"We want kids to be active, and to be active on a daily basis," said Dr. Frank Dawson, director of sports medicine at MedStar Franklin Square Medical Center. "That said, you really have to be careful. Their bones and muscles haven't fully developed, making them prone to overuse injuries."
Dawson and other experts caution against overly strenuous workouts, especially those that involve lifting weights and running long distances. Girls racing long distances, for example, may increase their risk of female athlete triad, a syndrome in which a low body-fat percentage can lead to hormonal changes that disrupt bone-building processes and increase the likelihood of stress fractures and breaks, according to the American Academy of Orthopaedic Surgeons.
Waiting to introduce some exercise programs until children reach a certain age may also help, Dawson and other experts say. He typically recommends that young athletes stick to body weight exercises such as push-ups, sit-ups and planks, and delay lifting weights until they're in their sophomore or junior years of high school.
"I see a lot accidents in the weight room," said Dawson.
However, some of the fitness programs currently popular with adults are great for kids, Dawson said. Examples include cross-training, "muscle confusion" workouts that expose different muscle groups with rest periods, and "mind-body" programs such as yoga.
In some youth exercise programs, the benefits extend beyond the physical. Many include mentoring and team building. For example, Girls on the Run and Heart & Sole, after-school running programs, teach life skills to girls in third through eighth grades during training for a 5K.
"They're learning goal-setting … good nutrition, how to handle stress, be part of team, including how to have difficult conversations and show compassion," said Susan Thaxton, executive director of Girls on the Run of Greater Chesapeake.
At the end of the program, they work on a community service project.
The combination is proving attractive — the local affiliate has grown from 30 girls running around an Annapolis track 10 years ago to 815 participants in more than 50 schools in Baltimore City, Baltimore County and Anne Arundel County today.
Other programs are seeing similar surges in popularity.
Last year, the Baltimore Running Festival registered 1,200 runners under the age of 18. There were several hundred more youth runners in the festival's 5K than the year before, said Dave Gell, director of communications. And several hundred more are expected this fall, he said.
The festival also hosts two kids' fun runs — one for ages 7 and under that is about 100 yards, and one for ages 8 to 12 that is two-tenths of a mile. Everyone — whether completing a marathon or being pushed in a stroller — ends at the same finish line, to have that euphoric experience.
"We hope to ingrain that love at an early age," said Gell. "The family that runs together stays healthy together."
Tracey Conrad, a mother of two from Ellicott City, said she's glad that her 10-year-old daughter can see other women in the CrossFit gym.
"I didn't have a role model for physical fitness growing up," said Conrad. "It's nice that she can see women who are strong and active."
Sabrina Clever, an Elkridge mother of two, has seen the confidence of her 6-year-old son, Aiden, skyrocket since starting CrossFit Kids about six months ago. At the time, he was being bullied in school. But these days, "He feels stronger. And that's helped him deal with [issues at] school."
Just having a fun workout has mental benefits, said Jeeter. "This gives them an opportunity to get their juices flowing," he said. "They never come home in a bad mood."