Let Your Kid Climb That Tree

The Atlantic

12-07-2025

A bunny, small enough to nestle in a cereal bowl, has recently started hanging out in my backyard. Now and again, it nibbles a plant or lies in the sun. Mostly, it explores the limits of movement, zooming, darting, feinting, and trundling through bushes. Once, I saw it corner so hard that it sprayed mulch in a giant, messy arc. A human kid who did that would almost certainly be called inside to clean up. But I haven't seen the adults in this bunny's life in weeks; the baby has carte blanche. If only more of the kids I know could be so lucky.
Wild animals are the best movers on the planet, and little ones spend much of their time frolicking, fighting, leaping, and climbing. From birth, human children share animals' potential for wild movement; left to their own devices, they would presumably tumble about like puppies. But more and more, they do nothing of the sort.
This is due in part to the human trend toward self-domestication, and also to the structure of modern society. The World Health Organization says that 81 percent of adolescents worldwide do not get enough physical activity, noting that rates of sedentary behavior in young people tend to rise as their country develops economically. In some American cities, the Trust for Public Land says, as many as two-thirds of children lack access to the kinds of nearby parks that would encourage free play. And a report by the Aspen Institute's Project Play initiative, a national program aimed at increasing youth-sports participation, concluded that compared with other activities, such as organized sports, 'free play is all but a thing of the past.'
Some kids lack access to woods, fields, and other open spaces where they might romp free. Some have parents who forbid that brand of tomfoolery. In the United States, many parents habitually tamp down on horseplay out of fear of injury to their children (or their furniture)—or because social norms dictate that they get their squiggly kids unsquiggled and into waiting rooms, subways, stores, airplanes, and restaurants, where children are expected to 'behave.' That impulse, however, risks reinforcing the notion that sedentariness is preferable at a time in a kid's life when they really do need to move.
Turn over almost any rock in the stream of health research, and you'll find warnings about the dire consequences of idleness, as well as abundant reasons for children to explore free movement. Children who move have healthier bones, muscles, and joints, and lower their future risk of obesity and chronic disease. Research has found that active kids develop superior cognitive skills, get better grades, and are more likely to stay on task than kids who are less active. In a systematic review of studies, researchers found that active children are more likely to report feelings of well-being. And a study published in The Lancet that examined the prevalence of adolescent depression among English youth suggested that increased sedentary behavior in adolescence could affect a person's mental health into adulthood.
Childhood might be a particularly costly time to not move, because this is when developing brains prune unused potential. 'One extreme view' of this neurological dwindling 'would be that you start out wired up for every possible contingency,' the Harvard neuroscientist Jeff Lichtman said in an article in Proceedings of the National Academy of Sciences —but as you age, unused connections in the brain get permanently disconnected through a process known as synaptic pruning, leaving you with 'a narrower nervous system.' We're used to the idea that young, plastic brains have an easy time learning to speak Mandarin or play piano; this is also true of learning how to do backflips, balance on a slackline, or throw a fastball.
Parents go to great lengths to keep kids safe; it's the core of the job. But restricting kids from encountering tricky movement problems, such as racing at full speed down a rocky slope or climbing high in a tree, can exact a toll. As Marcus Elliott, a physician and one of the world's most prominent injury-prevention experts, put it to me: 'Your fear that your kid will get hurt is depriving them of something they'll never get back.'
Elliott runs the Peak Performance Project, known as P3, a movement lab in Santa Barbara, California, where many athletes—a huge percentage of NBA, NFL, and MLB players—have been found to be at risk of injury because of deficiencies in their movement quality. P3's researchers focus on 'kinematic movers,' whose bodies have a ready solution to almost any movement problem: They can land on either one foot or two, jump every which way, and change directions easily. They're not always the highest jumpers or the fastest sprinters, but, at least among a well-studied cohort, they are likely to play for a long time without injury.
This is why Elliott recommends that children play like animals: He suspects that every adult kinematic mover grew up playing freely like that fuzzball in my backyard. The robustness necessary to repel injury has little to do with getting in cardio, running fast, or jumping high. Instead, he says, robustness has to do with 'movement quality,' which is to athleticism as fluency is to language.
This tracks with an observation made by the journalist David Epstein, who writes in Range: Why Generalists Triumph in a Specialized World that athletes from tiny towns have irrational levels of success. Epstein's theory is that with a shortage of players, small towns need the best athletes on the football, baseball, and basketball teams. Playing a variety of sports might foster a person's robust movement vocabularies.
Thankfully, providing kids with more freedom doesn't require a lot of money. Mostly, it just requires a little creativity.
Almost every kid who comes into my house feels a deep urge to romp on the huge yoga ball in our living room (which cost less than $20). They body slam it, Superman across its top, throw a sibling into it, and do other bonkers stuff. Many parents who witness such behavior grow anxious, shout bossy directives, or declare the ball off-limits entirely. Of course, I understand; no one wants to end up at urgent care. But I'm also aware that kids who start out falling down go on to quickly develop new skills. Some blossom into pro-grade yoga-ball surfers. When my son was young, he developed an uncanny ability to perch on all fours atop the ball even as someone (honestly: me) forcibly shoved him this way and that. He's now a 6-foot-1-inch engineering undergrad; we have not outgrown this game.
Elliott told me that when work would keep him on the laptop during weekend afternoons, he'd give his kids small physical challenges: Can you hop on your left leg all the way across here, and then clear that hurdle? Can you step off that ledge, land, and leap right back up? One of his daughters remembers earning dessert by hopping a giant lap of the backyard on her left foot. Elliott and his children also wrestle one another like puppies do. In this way, he explained, his kids learn how to perform complex movements while keeping one another safe—by, say, avoiding the corner of the coffee table.
All of this free play can help when kids start taking up play of a more serious kind. Many sports injuries come from iffy form when landing. Kinematic movers do well, Elliott's lab has found, because they land with active feet that greet the ground, as well as ankles, knees, and hips that flex nicely in time with one another—perhaps because these movers practiced so much free play as kids. P3's trainers spend long hours putting athletes through the grueling work of mastering landing technique as teenagers or adults, remedial lessons that appear to have a big impact. A 2022 study found that ACL-injury-prevention training, which generally includes landing and explosive movement, reduced ACL tears by an average of 64 percent among young female athletes. (This aligns with research on ballet dancers, among the few groups who train from a young age to land properly. They may sustain plenty of sprains and other overuse injuries, but they also have a striking shortage of ACL tears compared with other athletes who jump as much.)
Eric Leidersdorf, a movement scientist and the president of P3, has more than a decade's worth of experience poring over the movement data of elite athletes. He also has an 18-month-old daughter. I asked him if he intends to apply the lessons of his day job to parenting. 'Absolutely,' he replied. He then used the word play 10 times in two minutes. 'My real hope is that she explores the world,' Leidersdorf told me. 'I want her to love moving and find joy in that.' I know a bunny that probably gets it.