Still, the hardship was difficult to hide. Castles often rummaged through the donated-clothes bin at the church where her father worked as a sexton—her mother was sick and unable to contribute—and regularly relied on teachers, friends’ parents, and church members for everything from food to fees for summer running camp. Her parents went to approximately two of her races. They would have gone to more, she says, but after one race another parent scolded them for smoking, blaming them for triggering the asthma attacks that Castles frequently experienced. Her parents never went back.

Castles, who went on to graduate from medical school, resumed competitive running in her 30s. She ran her first marathon at 36 and qualified for the Olympic Trials in Boston, finishing in 2 hours and 42 minutes. She qualified again at age 40. Now a doctor of psychology at two Veterans Affairs hospitals in New Jersey, where she coaches running, she’s also an adjunct psychology professor at Farleigh Dickinson University.

Castles developed her dazzling athletic talent with the active support of coaches and other adults who filled in when her impoverished family foundered. Thousands of kids today endure similar material deprivation—some 21 percent of children live in households with incomes below the federal poverty threshold—and many lack athletic opportunities because of it. Indeed, the fruits of America’s fixation with youth sports are largely concentrated among children with means: According to data recently released by the Aspen Institute’s Sports and Society program, household wealth is the primary driver of kids’ athletic participation. Compared to their peers whose families make more than $100,000, children ages 6 through 12 whose family income is under $25,000 are nearly three times as likely to be “inactive”—meaning they played no sport during the year—and half as likely to play on a team sport even for one day. “Sports in America have separated into sports-haves and have-nots,” said Tom Farrey, the executive director of the Sports and Society program.

Concern about the kids’ sports frenzy often fixates on the costs to children who do too much: the burnout and physical exhaustion, the bodies battered from overuse, the loss of unscheduled free time. But the children who are excluded from that frenzy, most of them from lower-income families, suffer more enduring losses. These children miss out on the scads of positive outcomes that are linked to regular exercise, including longer life expectancies, improved mental and physical health, and better grades in school. As important, they are denied lessons in discipline, teamwork, and resilience—the very qualities that most parents want for their children—which are often taught in athletics. And despite the well-documented advantages of athletics participation, it’s unclear whether the loose coalition of businesses, community organizations, and nonprofits that are working to ensure all children have access to sports have the resources or clout to make it happen.