The video—it has now been viewed tens of thousands of times—is just 16 seconds long, but the brevity doesn’t make it any easier to watch. Catherine Harnden, a Canadian downhill mountain biker, is competing in the 2012 O-Cup, a race series held every summer throughout Ontario. The clip, shot by a spectator, starts with a view of the lodge at Sir Sam’s ski area in Eagle Lake, about 100 miles north of New York state. The onlookers are chatting, then there’s the stutter and bump of tires on dirt. Harnden, dressed in white and green racing skins with spiderweb graphics, hurtles into the frame from the lower left. She hits a tabletop jump, but her weight is in the wrong position, and in a flash she launches over her bars. She lands on the ground headfirst, with a chilling thud. There’s a groan from the crowd. “Rider down! Rider down!” a voice announces over the PA.

Harnden, 23, doesn’t remember much about the crash. Her recollection is pieced together from photos, witnesses, and friends who were at her bedside when she woke up in the hospital. Now she and I are sitting at the counter of the crowded Coffee Pot café in Littleton, New Hampshire, near her home. This is one of those lucky former northeastern mill towns that has figured out how to thrive in a postindustrial age, its Main Street a mix of craft stores, booksellers, and a half-dozen coffee shops. Harnden has just gotten off work; she cohosts a morning talk show on WLTN radio, whose offices are across the street. She has long blond hair, and she’s muscular and smiling. She’s also amped, energized after a few hours on-air. She insists she doesn’t mind if I replay her wipeout on my phone so she can walk me through the details.

“Are you sure?” I ask.

“Definitely,” she says. “But you’re gonna mute it. I can watch, but I can’t stand to hear that crunch.”

Harnden’s accident video is still featured on several major bike sites that promote click-generating reels of wrecks like hers. Describing the crash as we watch, she agrees with some of the online commentary about what went wrong. “It was a basic, easy table,” she says, “but I came into it with too much speed, and somehow I found myself on the lip of the jump grabbing a whole handful of brake and getting my weight too far back.”

Will parents come to think of skateboarding and mountain biking the same way some now think of football—too risky for a child?

In the emergency room, Harnden looked across the hall and saw another competitor—a close friend—wailing in pain after shattering his collarbone. Harnden’s elbow was dislocated, but she was stoic. She wasn’t aware of her severe concussion. She doesn’t remember yelling at the ER doctor not to cut off her prized team jersey.

In retrospect, Harnden says, it was a practice run before the crash that threw her off her game, rattling her ability to concentrate. There’s no video of it, but Harnden doesn’t need footage to reconstruct what happened. “I was coming down to a hip jump,” she says, referring to a feature in which the launch slope points in a different direction than the landing. “It was in the trees, and I didn’t clear it. I bounced off the landing and ate it. I hit my head hard, but I didn’t lose consciousness, and I rode myself down to the pits.”

There, sitting dazed and cross-legged on the grass, Harnden knew she needed to remain still. “But everyone was telling me I should take another run, that I needed more practice. And I was like, they’re right. That can’t be my last run before the race. So I went back to the top.”

Her next time down, Harnden cleared the hip jump. “That’s awesome,” she remembers saying to herself just before arriving at the next obstacle, the tabletop. Then everything went dark.

Harnden still races and is now sponsored by Mongoose bikes. She’s a ski coach at the nearby Bretton Woods resort. She’s out almost every day, running and hiking the trails of the rugged Presidential Range. You’d never guess that, four years later, she still struggles with basic memory, not just of the crash but also of the name of a man she once dated or a flight she booked for the holidays. She can’t go to loud parties, stare at bright lights, or watch point-of-view action-cam footage. “It makes me hurl,” she says.

Harnden says she’s a different person now than she was before her head injury. Pre-crash, she was “cocky and extroverted.” Now she experiences mood shifts, depression, and fears that come and go, and migraines sometimes force her to retreat for two days into a dark room. Most of the time—when Harnden’s out on her bike, competing, or helping to launch a clothing company—things are “very good, great, in fact.” But the bad periods still come.

One thing she’s certain of: “I shouldn’t have gone back up that day.”

When the news broke in May that Dave Mirra—a BMX superstar who won 24 X Games medals and countless other competitions during his career—had chronic traumatic encephalopathy, it’s no exaggeration to say that everything changed in the world of action sports. CTE, a degenerative brain disease that can occur after repeated head trauma, is most often associated with NFL players and combat veterans. Classic symptoms include mood swings, severe headaches, confusion, and dementia, and the condition can lead to depression, erratic behavior, dependence on drugs and alcohol, and suicide. Several high-profile NFL players who took their own lives were shown after autopsy to have had CTE, including Hall of Fame linebacker Junior Seau, who died in 2012 at age 43, and former Chicago Bears safety Dave Duerson, who shot himself in the chest at age 50 in 2011, leaving a note requesting that his brain be examined.

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Mirra, 41, committed suicide in February, and many speculated that a series of concussions and head injuries he experienced during years of competing, in addition to cracking his skull at 19 when he was hit by a car, might have contributed to his death. When the stunt rider’s wife, Lauren, confirmed to ESPN The Magazine that Dave had CTE, questions that previously had been whispered became headlines. Do sports like road and mountain biking, BMX, skiing, snowboarding, surfing, and skateboarding—all of which can result in repeated knocks to the head—pose a risk of concussion and CTE similar to what we’ve seen in the NFL?

While head trauma is common in action sports, it doesn’t occur as frequently as it can in football. But with ever advancing gear that makes huge jumps—and huge impacts—possible, and an audience that thrives on risks and wrecks, action-sports athletes are going bigger, higher, and faster than ever before. Head injuries and their outcomes range widely—from concussions that fully heal, to a condition called post-concussion syndrome that can take months or years to resolve, to more serious traumatic brain injuries and CTE. Meanwhile, research shows that it doesn’t take a large number of concussions to cause adverse consequences and that concussion rates are increasing among action-sports athletes. A study that analyzed more than four million emergency-room visits in the U.S. from 2000 to 2011, conducted by researchers at Western Michigan University and published last year in the Orthopaedic Journal of Sports Medicine, reported a steadily rising number of concussion injuries in seven sports: surfing, mountain biking, motocross, skateboarding, snowboarding, snowmobiling, and skiing. Snowboarding was the most concussive activity, with 42,811 concussions over that ten-year period.

Of the summer sports, the researchers counted 28,328 skateboarding-related concussions, 3,242 in surfing, and 4,530 in mountain biking. The latter number doesn’t include statistics from BMX, which hasn’t been widely studied yet and would likely make the figure much higher.

Sadly, Mirra isn’t the first action-sports athlete to have taken his own life after a series of head injuries. Several competitors in BMX and skateboarding have also committed suicide. Whether their deaths were related to head trauma is impossible to confirm, but the families of the deceased often describe symptoms that fit.

Biker Sherlock, whose first name was Michael, gained fame as a downhill skateboarder and street luger, winning multiple medals at the X Games and Gravity Games between 1996 and 2002. On the morning of December 3, 2015, two months before Mirra’s suicide, a surfer checking the waves at San Diego’s Pacific Beach found a body at the bottom of a stairway leading down from a parking lot. The victim, later identified as Sherlock, had shot himself in the head. He was 47, and he left behind a wife and two young boys.

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Sherlock’s family has never spoken publicly about the cause of his death, but in response to my request for an interview, his sisters Margaret and Marjorie provided a statement that read, in part: “Michael had his first brain injury at the age of 7. He rode his bicycle down a hill with no hands, the bike stammered over rocks and Michael went down—resulting in a fractured skull. In his professional action sports life he sustained many concussions—all the while wearing the best in protection in helmets. The world is coming to know more every day of the life-altering and sometimes tragic loss of life due to the effects of brain injury. While Michael was not officially diagnosed with CTE, no other conclusion can be drawn—his last act demonstrated this.”

A year and a half earlier, less than ten miles away, a white Pontiac minivan was found idling and abandoned on the Coronado Bridge, the sweeping 2.1-mile span over San Diego Bay that connects San Diego and Coronado Island. The van belonged to professional in-line skater Bryan Bell, 36, who appeared in the X Games and many other competitions during the 1990s. Bell had taken countless hits to his head. “Smashing your helmet or face planting was a constant thing,” Bell’s older sister, Cari McLaughlin, told me. She said that Bryan experienced frequent migraines “to the point of tears” and depression that he “self-medicated with alcohol.”

When McLaughlin was called to the bridge by police, she told me, she looked down and thought, “If anybody could have survived this jump, it would be Bryan. He was that much of a daredevil.” On September 1, 2014, Bell’s body was recovered from the bay.

Presence of CTE can be confirmed only by a brain autopsy, and neither man’s brain was examined. It’s important to note that not all head trauma leads to the disease. But Mirra’s diagnosis, along with mounting scientific and anecdotal evidence, has many pros wondering if we’re on the verge of a CTE epidemic among action-sports athletes. More shocking are the signs of widespread health consequences from concussions in the amateur ranks—people like you and me.

“This is a very messy case,” says neuropathologist Thor Stein as he delicately slices a human brain into thin strips. The tissue is discolored, he says—pale gray when it should be pinkish—and seems, even to an untrained observer, almost ragged. “This is a person who would have had major cognitive issues.” Stein hands a slice to a colleague to mark for further study.

This narrow room at Edith Nourse Rogers Memorial Veterans Hospital, in Bedford, Massachusetts, is dominated by sharp tools, a stainless-steel table, and refrigerators. In the latter, behind glass doors, I see buckets about the same size as jumbo ice-cream tubs, each marked with a number. Inside are human brains. This facility holds the world’s largest collection of cerebral matter donated by professional and amateur athletes who wanted to further the cause of CTE research. To date there are some 320 athletes’ brains here, and more are on the way. Among others, soccer star Brandi Chastain and Nascar driver Dale Earnhardt Jr. have agreed to donate their brains after death.

Stein tells me that only one athlete from the action-sports world—an 18-year-old snowboarder who committed suicide six months after he’d suffered a concussion—has supplied brain tissue to the Rogers facility. It showed signs of CTE, he says. (Mirra’s family had his autopsy performed at the University of Toronto.)

Stein, who is part of Boston University’s Alzheimer’s Disease and CTE Center, performs cerebral autopsies here every Thursday. (The CTE Center’s labs and Brain Bank are housed at Rogers.) The veterans hospital opened in the late 1920s to help soldiers returning from World War I cope with an unexpected array of symptoms, including mood swings, depression, headaches, and suicide. As the U.S. population began living longer, the facility’s mission expanded to include diseases, like Alzheimer’s and Parkinson’s, that afflict older patients.

The CTE Center’s director, neuropathologist Ann McKee, became interested in CTE after finding a buildup of tau protein, now known to be a clear indicator of the disease, in the brain of a boxer in 2003. In 2008, Chris Nowinski, a former professional wrestler who cofounded the Concussion Legacy Foundation with Robert Cantu, a Boston University clinical professor of neurology and neurosurgery, asked McKee if she’d look at an NFL player’s brain to see if it showed signs of CTE. (It did.) Later that year, McKee teamed up with Nowinski and Cantu to form the CTE Center, which works with the Concussion Legacy Foundation to acquire athletes’ brains.

Since 2008, McKee, Stein, and their CTE Center colleagues have examined the brains of 94 former professional football players. Ninety of them have shown markers for CTE. (Bennet Omalu, a Pittsburgh-based neuropathologist, was the first to discover the disease in an NFL player—in the brain of legendary Steelers center Mike Webster—in 2002. Omalu’s push to change the concussion policy in the NFL was dramatized in the 2015 movie Concussion.)

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CTE occurs, Stein explained, from an accumulation of impacts, both concussive and subconcussive. (The latter is a milder hit that does not lead to obvious symptoms.) Scientists don’t yet understand why some people develop the disease and others don’t. Stein says the best indicator of future problems isn’t necessarily the number of concussions but how long an athlete plays a sport that includes regular impact.

The physiology of a hit is pretty simple. It begins, for example, with you falling off your bike, snowboard, or skateboard. As you’re flying toward the ground, your brain is floating inside your skull, suspended in a layer of clear, colorless fluid, like a bowl of Jell-O that hasn’t quite set around the edges. When impact occurs, it’s the shaking of the brain inside your skull that causes the concussion. “That force—the banging, the twisting, the rotation, the acceleration and deceleration—deforms the brain and causes damage to the neurons and other cells that help the brain function,” Stein says. Initially, you may or may not lose consciousness. Later you might experience memory loss, nausea, equilibrium problems, or headaches—sometimes for weeks, sometimes for months.

The damage you sustained—and any further injury after that, especially before the brain has fully healed—can lead to problems with the transport of proteins in the brain, the same way potholes might impede the smooth flow of traffic on a city street. In fact, this metaphor is nearly literal. As Stein slices the brain he is working on, he shows me spots where trauma created visible gaps in the tissue.

Stein also says that an athlete doesn’t need to take a direct hit to the head to incur damage. “Sports where riders make these big landings could cause problems,” he says. “They’re 20 feet in the air, and their brain is falling at high velocity, just like their body. When they stop, the brain keeps moving inside the skull. They don’t have to have pain. They don’t have to say ouch.”

Stein, McKee, and their colleagues have identified four stages of CTE. In the first, tau protein builds up, mostly in the brain’s frontal lobe. As levels of tau increase in stage two, pathways in the brain called microtubules become twisted. Then they collapse, degenerating into neurofibulary tangles, effectively acting as roadblocks to normal function. It’s in stage two that symptoms like aggression, depression, and impulsiveness begin to appear. In stage three, as the tau spreads, the most essential parts of the brain—the mood, memory, and learning controlling amygdala and hippocampus—lose function. By stage four, the brain is overloaded with tau deposits, sometimes shrinking to half its original size. Ultimately, it can no longer perform the basic functions required for life.

Before Mirra’s family had confirmed the BMX rider’s CTE diagnosis, I spoke to McKee. She said that permanent brain trauma “is something athletes in those kinds of sports should be very concerned about.” I told her about other concussed athletes I’d interviewed, and she became distressed. “We need to figure out a way to help these people,” she said. By their nature, action sports are often individualized and not always overseen by a governing body. “We don’t have a great way to find out what’s going on out there,” McKee said.

Preventing and healing CTE is McKee’s ultimate goal, but she’s equally concerned about weekend warriors who’ve had a few serious knocks to the head. What should an athlete who has a concussion do? McKee paused. “Right now we’ve got no effective treatment besides rest,” she said. “We need to be sure we can figure out when somebody has recovered.” She paused again. “But we don’t really have a way to do that, either.”

“I’m sorry I’m not giving you firm answers,” she said. “That’s because there aren’t any.”

Even if you don't follow mountain-bike racing, you may have heard of Missy Giove. Through much of the 1990s, she was one of the most outrageous and exciting athletes in the sport. When Giove won the 1994 downhill World Championship in Vail, Colorado, she had wild dreadlocks, wore a dried piranha she called Gonzo around her neck, and rode faster and crashed harder than anyone else, regardless of gender.

Giove kept racing for another decade, winning 11 more World Cup events and appearing in the X Games, where she took the women’s downhill gold medal in 1997. But by 2003, she was suffering from multiple injuries to her brain and body. She began to have seizures and severe migraines. In 2009, she was arrested for transporting 400 pounds of marijuana in upstate New York. She avoided jail time and is in the last year of a five-year probation.

Giove is now 45, married, and living in Virginia Beach, where she works at local marinas, maintaining private boats. She knows that her many crashes made her “different mentally and physically.” She says her worst symptoms are migraines. She gets “tunnel vision and pretty much can’t move. Everything’s dark, you’re throwing up.” What helps, she says, is rest, a vegan diet, and “a skill that I’ve developed, or acquired, through experience.” She turns off the lights, submerges herself in a warm bath, and makes sounds, which she describes as “oscillating singing,” underwater.

There are signs of widespread health consequences from concussions in the amateur ranks—people like you and me.

As Giove sees it, the consequences of her crashes are part of a life she still loves. “There are things about my mind and body that have changed. I deal with it, but I have to not be hung up on how I used to be,” she says.

In 2015, Giove entered a World Cup race in Windham, New York, her first competitive event in more than a decade. She came in a respectable 17th in the qualifier, making it to the finals, where she crashed on a jump over a section of the course called a road gap. Giove recorded the event’s third-fastest top speed, but one of her longtime friends and sponsors, John Parker—the founder of Yeti Cycles, who’s launching a new mountain-bike brand called Underground Bike Works—expressed concern about her continuing to race. “I don’t know that I could in good conscience put her on a bike again,” he says. “I worry about her crashing.”

Many other young athletes I spoke to, all of whom have experienced multiple concussions, wonder about their futures. Robin Carpenter, a 24-year-old road cyclist on the Holowesko-Citadel Racing Team, has competed on bikes since he was 16 years old. He told me he’s had four concussions—one as a child, while skiing, and three as a cyclist, including one on February 7, 2016, during the CBR Dash 4 Cash near Los Angeles. A rider made bike-to-bike contact and Carpenter went down, landing on his side, hitting his head, and cracking his helmet.

As Carpenter recovered, he felt depressed. He rested a month and started riding again, but he was uncertain if his return to the sport would have repercussions and whether his team would see him as a liability. He no longer has those concerns, but he is worried about the long term if he sustains more concussions. “I picture myself 20 years from now, and I see myself just sitting, not reading, not able to watch television, not do anything,” he says. “And I wonder whether this is all worth it.”

Another road biker, 21-year-old amateur Cameron Rex, decided to stop racing in 2014 due to burnout. He sustained three concussions while cycling and two more during other activities. “The trouble with this kind of injury is that it gets worse,” he says. “Four or five big hits start to compound.” Though Rex can’t definitively attribute any cognitive issues to head injuries, he told me that he noticed changes in his handwriting when he went back to college in 2015. “When I got to school, my handwriting was terrible,” he says. “I had to learn cursive so I could write neatly.”

USA Cycling, the governing body for professional and amateur road and mountain biking, has a post-crash protocol for riders who may have sustained a concussion, but the young riders I interviewed said that the information they’d received about it varied widely. It depended on the team and the event. “You look at other sports, they seem to tell you what to do,” Rex says. “You don’t see a lot of that in the cycling world.”

The main page for concussion information at the USA Cycling website, titled Concussions in Cyclists for Team Managers and Coaches, links to some important resources, including several concussion and cognitive-baseline-assessment tests, the Centers for Disease Control and Prevention’s concussion pages, and the Zurich Concussion Consensus page, which has information on the first attempt to create a worldwide policy aimed specifically at athletes. USA Cycling is affiliated with the Union Cycliste Internationale (UCI), the sport’s global body, and both have policies recommending that riders be withdrawn from competition and taken to a medical facility if they experience symptoms that include disorientation. But the ethos of the sport means that many keep going. On day three of the 2015 Tour de France, 20 cyclists went down in a clattering pileup. Though several withdrew, Swiss rider Fabian Cancellara, who’d been leading until then, continued, despite a team manager telling journalists that Cancellara felt “groggy.” Cancellara withdrew from the race later that day with two broken vertebrae.

“A lot of it goes to the athlete’s mentality,” says Davis Phinney, a former professional cyclist who partially attributes his early-onset Parkinson’s to crashes he’d suffered while racing in the eighties. “We get into these sports because we want to do something different. We see the sports as counterculture, even if it’s a huge commercial enterprise. When you get injured, that mindset doesn’t help you.”

According to some neurologists, in the heat of an event, the best practice is to give athletes who’ve hit their head, yet appear to be OK, at least 15 minutes of evaluation before letting them return to competition. This isn’t possible in the context of bike racing. A racer shaking off a crash while lying on the side of the road has a split-second choice: either get up fast, because the peloton is speeding away, or quit. While event rules and protocols vary, the decision to start pedaling again is sometimes made by the athlete or the team manager, who is trailing behind in a support vehicle, and not always by a medical professional.

Concussion policies at many sports organizations are undergoing rapid change as more and more information comes to light. USA Cycling is no exception. According to technical director Chuck Hodge, the organization is aware that its head-injury policy needs to evolve, and it’s in the process of putting together a medical consulting team that will recommend more stringent rider-safety protocols. Hodge says USA Cycling is seriously considering a “mandatory withdrawal policy” for athletes who’ve had head injuries. “The challenge is in the implementation,” he says. “How do we make this happen at all levels of racing? It opens up some very broad questions for our sport.”

The U.S. Ski and Snowboard Association’s concussion policy on its website includes language that says athletes who have sustained concussions or brain injuries must immediately be removed from any USSA event and cannot return until they’ve been cleared by a qualified health-care provider.

Jeffrey Kutcher, a neurologist in Ann Arbor, Michigan, who specializes in athletic brain trauma, works as a team doctor and consultant to the U.S. Ski and Snowboard Team. Medically, Kutcher says, it isn’t a good idea to let athletes make the decision about whether to continue after banging their head. “It’s like asking the patron who comes wobbling out of the bar whether they’re good to drive,” he says. “It doesn’t make sense if somebody’s impaired.” Kutcher also believes that coaches shouldn’t be making that decision. “You don’t want a situation where somebody is automatically removed if they take a fall, but it’s a very defendable position to give the medical staff absolute control,” he says. “Don’t let coaches make the determination. Medical staff makes that decision.”

The situation is more complicated in sports like BMX and skateboarding, which have loosely arrayed governing bodies and a variety of disciplines. Most athletes compete as independent contractors, and there’s often a void as to who’s responsible for setting concussion and injury policies—and lots of questions about how, and by whom, it should be filled.

The larger action-sports competitions are controlled by media organizations like ESPN, which runs the X Games, or consumer brands like Red Bull, which has multiple events and also sponsors many athletes. These entities don’t act as leagues or governing bodies. What’s more, athletes might enter a variety of competitions throughout the year, many of them operating independently of one another. While most have extensive safety protocols and on-site medical and evacuation resources, providing things like concussion policies and coverage for injuries hasn’t typically been the job of event producers or sponsors, and athletes are required to carry their own health insurance in order to compete.



While there are hundreds of competitions each year, Red Bull’s Rampage free-ride mountain-bike contest may be the most thrilling. It also illustrates some of the knottier issues in action sports. Rampage is a work of aerial art, in which a by-invitation-only group of riders compete in the cliffs and canyons of Virgin, Utah, doing things on a bike that should be impossible—and sometimes are.

At the 2015 Rampage, 19-year-old freeride phenomenon Nicholi Rogatkin, currently ranked first in the world and sponsored by a host of gear manufacturers, missed a drop and rode off a cliff. His helmet-cam footage shows him tumbling and twisting, and you can hear him groaning, but you really have to see the video shot from a distance to appreciate how far Rogatkin fell. After he gets up, he’s back on his bike within moments, despite apparent damage to the front of his helmet.

In an interview conducted just after his run and aired during the December 27, 2015, edition of Red Bull Signature Series, on NBC, Rogatkin said, “I was just waiting to go unconscious, but I stopped, finally, got up, checked that my bike was OK, put my helmet back on, got the OK from the judges to drop, not really the OK from the medics, but went anyway and finished my run.” (Rogatkin walked away with only minor injuries.)

Red Bull doesn’t list an athlete concussion policy on its website and declined requests to comment on whether it has a head-injury protocol for its events. When asked about athlete injuries, communications director Patrice Radden offered a written statement. “Red Bull provides platforms for world-class athletes to realize their dreams,” it read, in part. “The safety of spectators and participants is always our primary concern.”

Some Rampage riders didn’t respond to interview requests, but Logan Binggeli, who took home the bronze medal in 2012 and placed 15th in 2015, and Cameron Zink, the 2010 champion, said they weren’t aware of a concussion policy at the event. Zink, the current world-record holder for the longest horizontal distance covered in a backflip—more than 100 feet, performed at the 2014 X Games—has been trying to get better compensation and safety protocols for Rampage athletes. After the 2015 competition, he and a group of riders met with Red Bull to ask for some changes to the event, including an updated policy for injuries, a rest day, a larger purse (in 2015, it was $100,000), and for the company to pay gap insurance, so that athletes’ deductibles would be covered. (Action-sports riders are able to get health insurance through the Affordable Care Act, but many have only the most basic policies, which often come with high deductibles.)

“The Rampage is incredible,” Zink says. “I love it. Some of the best times I’ve ever had have been there. We all feel that way, and Red Bull knows it. We get taken advantage of because we’re going to do it regardless. We’ll do it for no money, so they can shove us in a corner and we have no rights.”

On June 23 of this year, the company announced changes to the 2016 Rampage format. The biggest was that a new venue, not far from the old one, would be used, and that the rider-built obstacles would be limited to those constructed by hand or with hand tools, potentially resulting in smaller— and less risky—stunts. The number of riders invited was reduced to 21, and the rest day that Zink and his colleagues had asked for was added. The purse was increased to $150,000, and riders will receive $4,000 each for expenses. But there was no word about gap insurance or injury policies. In her statement to Outside, Red Bull’s Radden said: “The industry practice for almost all events is that individual health care coverage is the responsibility of the participating athletes. Any incidental costs are expected to be covered by such individual’s health insurance provider.”

Other Rampage riders I spoke to think the system is working, citing expert on-site medics and the opportunity to compete in carefully planned venues broadcast to large audiences, and adding that it’s up to riders to know their limits and not push past them.

But given the nature of many action sports, there’s an acute likelihood of sustaining head and other injuries, even for the best in the field. One of Dave Mirra’s signature moves was a double backflip, which he first executed off a BMX ramp built on San Francisco’s Pier 30 for the 2000 X Games. It was one of the most astounding feats ever accomplished on two wheels. But he also crashed, badly, at other events. So have dozens of other riders—at competitions, on the trail, and in practice at backyard tracks.

When asked if Mirra’s death has prompted a rethinking of medical protocols, Danny Chi, director of communications for the X Games, offered a written statement. “Athletes who are determined by the X Games medical staff to have sustained a concussion will not be allowed to continue to participate in practice or competition for the duration of those Games,” it read. “We have made a commitment to provide top quality medical care for athletes at X Games events. We constantly examine and evaluate our processes and policies, always with one goal in mind: athlete safety. This is a topic we take very seriously.”

Meanwhile, the financial and emotional costs of head injuries can take a large toll on athletes and their families. In August 2011, 16-year-old Harley Taich was the top-ranked female surfer in California and was about to compete at a contest in Point Mugu, just north of Malibu, when she flew off her board and landed headfirst in the sand. She was diagnosed with a concussion but says she received conflicting medical advice.

“Some doctors told me to keep surfing, some told me to stay home and do nothing,” she says. Taich continued surfing and says she reconcussed—“dozens and dozens of times.” She reached a point where she could no longer balance properly and suffered near constant migraines and mood swings ranging from anger to “hysterical tears.” In 2013, she attempted suicide. “I did everything wrong in my recovery,” she says, “because I didn’t know what to do.”

When asked how she paid all the medical bills, Taich says, “I have grandparents. They’d been saving for my college all my life, and it was pretty clear I wouldn’t be going. So they paid for my treatments instead.” She estimates the total cost at almost $200,000.

After three years, Taich decided she’d take the rest that one of her doctors had recommended. After eight months of no surfing, no school, no electronics, no stimulation of any kind, and an improved diet, she began to feel better. Taich, now 21, says that most of her symptoms have diminished. She recently wrote a children’s book about her experiences, called Heads Up: The Story of Finn and Reef, to “get the correct information out there in a way that people can understand.” But her career as a professional surfer is done. “It was everything I wanted to be since I was four years old,” she says.

Professional athletes put themselves at risk far more often than most of us, but the new science of concussions is disturbing for amateurs, too. As an avid mountain biker who competed in both downhill and cross-country events throughout the 1990s and 2000s, I’ve had at least four concussions from crashes, including two in which I was knocked unconscious. In the most serious incident, nearly 20 years ago, I hit a tree on a downhill course in France. I was out for ten minutes and woke up with a broken eye socket and gashes on my face that required multiple stitches. Other than being told not to sleep for 24 hours—a myth that may actually make things worse—I didn’t receive a word of advice about brain injury.

In the years that followed, I married and had two kids. I haven’t had much time to ride the way I used to, and I haven’t taken a hard blow to the head in a decade. But I have found myself struggling with depression, attention, and organization. Some of my friends and loved ones would describe me as impulsive, at least some of the time. I can’t say that my concussions contributed to that; I can’t say they haven’t. I’m not sure I really want to know. I recently bought a new mountain bike, my first in over a decade, and was reminded as I sped down a Los Angeles fire road at 30 miles per hour how much I love the sport. But I’m worried about my slower reflexes and what might happen if I hit my head again.

The scariest part of all this are the cognitive consequences of a concussion that weekend warriors may face. A study published earlier this year in the Canadian Medical Association Journal looked at more than 235,000 men in Ontario who’d had concussions between 1992 to 2012. Among those who’d suffered a single concussion, researchers found that suicide rates were three times higher than those who’d never had a head injury. That rate increased to four times when the concussion occurred on a weekend, leading to a suicide frequency, the authors wrote, that “exceeded the risk among military personnel.”

The authors of the study say they don’t have a clear understanding of why the men who concussed during a weekend faced higher risks for suicide after a single concussion. But they noted that on weekends, people may not seek medical care as quickly as they might on a weekday.

“There aren’t great protocols for weekend warriors,” Jeffrey Kutcher says. “And we need to keep the general population in mind.”

One of my former riding buddies, Warren Shumway, remembers falling off his bike a lot. “I never thought about it much,” says Shumway, who is 55 and works as a textile-industry sales rep in New Hampshire. “I felt invincible.” But two years ago he was knocked out during a race. “That scared me. My son was less than a year old, and I sat in a fog for a couple of days,” he says. Since then he’s stopped racing and now has two boys, who he says “won’t be allowed to do extreme sports until they’re 16.”

I’m not sure if I’ll be that conservative with my boys. I want them to be fit and to learn that there’s reward in risk. How much risk? Hard to say.

Though there’s debate about what parents need to do when their kids sustain head injuries—rest is called for, but what kind and how much is something the medical community is still sorting out—Kutcher says that the most important thing is for parents to make smart decisions. “You have to ask, what’s your child’s plan for playing sports, and what are the risks?” he says. At U.S. Ski and Snowboard, Kutcher calls for pre-participation neurological exams for all student and youth athletes, and follow-up exams at least once a year to determine whether a child’s brain is tracking the right way. “Are there issues starting to come up,” he says. “If there are, why are they there?”

Kids are becoming more aware themselves. During an Amtrak trip down the Pacific coast recently, I overheard a group of teenage boys talking about concussions. They were all 17 and heading back to San Diego after a week at summer camp. One of them, a burly redhead named Remington Naves, had concussed three times, once surfing, once playing lacrosse, and once skateboarding. “I had a huge impact at the skate park in Carlsbad,” he said, “and I felt groggy for a week.”

Naves was so confused by the conflicting information he received afterward that he ended up doing a lot of research on head injuries. While looking into it, he learned that his father had suffered four concussions as a high school and college football player. “We’re concerned for each other,” he says. That concern was heightened when he heard about Dave Mirra’s suicide.

Naves had taken an Impact test, a cognitive measurement that helps provide a baseline for future results. Nearly all youth and college athletes in organized sports are now required to take the test, a 25-minute online series of questions and exercises designed to measure cognitive skills, reaction time, attention span, and memory. Naves said that, after a concussion he suffered while playing football last spring, he scored “17 percent lower” than he had on his initial test.

Will parents come to think of skateboarding, mountain biking, and other action sports the same way some now think of football—too risky for a child? Kutcher says there’s no reason for excessive restrictions. “We need to be vigilant about it,” he says, “but you can have concussions and have a healthy life after sports.” There’s variance, he explains, “in how much force it takes to cause an injury to any particular person’s brain, based on genetic factors and maybe some physiological factors. And there’s also a threshold that’s very individual in terms of how much injury it takes to produce a clinical effect.”

Kutcher’s point is that it’s an oversimplification to say that concussions invariably lead to cognitive problems. “I’ve seen athletes who’ve had many concussions and their overall brain health is fine,” he says. “We monitor them, but we let them continue to play. And I’ve had athletes who had just one or two concussions, and it seemed like the best thing for them to do was retire.”

Many athletes I spoke with pointed to helmet usage as a protective measure against concussions. Several new designs are available, and the technology continues to evolve. But the neurologists I interviewed said that at this time, helmets can’t prevent concussions.

“Concussion occurs when the brain moves,” says Kutcher. “Whatever you have outside your skull might absorb some force, but if you get hit on the helmet by something, your brain is still going to move.” Neurosurgeon Robert Cantu says that athletes need to continue to wear helmets to “reduce the risk of skull fracture, not concussion.”

For now the best protection may come from talking about CTE more, an idea expressed by Lauren Mirra, Dave’s wife, when she broke her silence about her husband’s death. “This is the beginning of bringing awareness of talks of better equipment,” she told ESPN The Magazine. “It would be amazing if this is something we can detect in life one day. If we can detect it, prevent it, stop it, let’s do all of the above.”

Biker Sherlock’s family offered a more sobering outlook. “It’s easy to feel like superman,” Sherlock’s sisters wrote in their statement, “when the adrenaline is rushing and you are part of something bigger than yourself, especially when surrounded by like-minded individuals who love their sport. From our perspective, at the end of the day, the medical, physical, and psychological consequences of the fleeting moments of elation will outweigh it all. Michael’s passion for sports was eclipsed exponentially by his love for his family and friends. The consequences of brain injuries took him away from us.”

What will it take to create change for athletes? Zink is considering forming a union to band riders together. Tim McFerran, president and founder of the World Skateboarding Federation, a two-year-old group that’s hoping to create a global body for skateboarders, is working on getting secondary insurance for skaters. The federation has 5,000 members and is one of the groups consulting with the Olympics as the sport is considered for 2020. “You have to create a co-op, or something like it, where everybody signs up together to create a big enough group that an insurance company would want to do business with,” McFerran says.

That’s a start, but obtaining NFL levels of recognition will require more. “Nobody has put together a cogent plan to get these athletes safe,” says Jay Fraga, a 44-year-old former BMX racer who retired in 2010 after suffering multiple concussions during his career. “That’s how the NFL got sued, that’s how there was so much human carnage in football. History is going to repeat itself.”

In 2012, Fraga started a website called the Knockout Project to provide an outlet for athletes who’ve suffered concussions to share stories and receive consistent, up-to-date information.

At this time, with most action sports existing as loose confederations, there’s often no single entity to bring to court, as NFL and NHL players have done. And for many athletes’ injuries, the statute of limitations on damages has passed, according to Michael Kaplen, an attorney who teaches brain-injury law at George Washington University Law School.

But, Kaplen says, “If somebody takes a fall and they’re allowed to continue, you’d have to ask: Did the organization have a rule? If they did, did they follow it? Should they have? Today everybody has knowledge of repetitive head trauma. Everybody has knowledge of keeping participants out of the game until they’ve recovered. If the organizations don’t do that, they could be liable.”

In the meantime, the race is on to figure out a way to test for CTE in living athletes. One possible method is being studied by Dara Dickstein, an adjunct assistant professor of neuroscience at New York’s Icahn School of Medicine at Mount Sinai. Building on work that has successfully detected markers for tau buildup in Alzheimer’s patients, Dickstein and her colleagues are investigating whether those methods can be transferred to subjects suspected to have CTE. The technique involves injecting a radioactive tracer into the bloodstream; the tracer binds to any tau proteins in the brain, which can then be detected via PET scan. Dickstein says she can’t discuss the study’s findings before they are published, but the initial results are promising, showing retention of the radioactive tau in the brain of a living 39-year-old former NFL player. She also mentions a difficulty she’s facing: finding control subjects whose brains are unscathed. “You look at the general population of men over 35, and it gets really hard to find anybody with no history of being bumped hard on the head or knocked out,” she says.

Meanwhile, Catherine Harnden had a full racing schedule this summer and had no plans to quit. “I love this sport,” she says. She’s moving from downhill to the enduro division. She’s feeling a lot better, and she says that prioritizing exercise, sleep, and a good diet has led to fewer occurrences of her symptoms. She’s also discovered that doing crossword puzzles and word games helps her to manage them.

We’ve made plans to meet later this year at the Highland Mountain Bike Park, in Northfield, New Hampshire, to launch ourselves off jumps of varying heights and onto a 50-by-50-foot airbag with massive Red Bull logos silk-screened onto it. It’ll be fun. In the end, I love my sport as much as any athlete, and as conflicted as I am about how and when to participate, I’m not going to stop. I can’t wait to fly through the air and land on that cushy bag.

One thing Harnden says she needs to do is get over hiding her injuries from her friends and loved ones. Doing so takes a lot of energy. She wrote in an e-mail that, throughout her life, she’s worked hard to “nurture a love of speed, adrenaline, endorphins. Because of that risk-reward ratio, I also became accustomed to injuries. It’s easy to pretend to be fine. As an athlete, it’s far easier to say ‘I’m OK’ than it is to say ‘My season is over.’ ”

Harnden concluded her note with this: “Concussions sit in a gray area where the athlete decides when to return to play.”

It’s a decision that can cost far too much.

Dan Koeppel (@soulbarn) is a former editor at Mountain Bike Magazine. This is his first story for Outside.