WASHINGTON (CNN) -- It's the kind of image that's too horrific to watch for some, too captivating to turn away for others.
Freestyle snowmobiler Caleb Moore, attempting a backflip with his snowmobile at the Winter X Games in Aspen, Colorado, couldn't rotate his machine enough to land the maneuver. The skis dug into the lip of the slope, bringing the 450-pound snowmobile crashing down on him. The vehicle slammed into Moore's head and chest.
After initially diagnosing Moore, 25, with a concussion after Thursday's accident, doctors soon discovered bleeding around his heart.
He had emergency surgery at St. Mary's Hospital in Grand Junction on Friday. Moore now has brain complications, and his family has issued a statement saying "Caleb is in critical condition and is being closely monitored. The Moores want to express their gratitude to all of Caleb's fans, friends and family for their strong support and ask for continued prayers in the coming days."
The case has brought increased scrutiny to the X Games, the combination of quirky, hair-raising events that were once pushed to the distant margins of televised sports but have in recent years been added to both Summer and Winter Olympic slates.
"They do train all year for this," says Dr. Christine Trankiem, a trauma surgeon at Medstar Washington Hospital Center, "But it's important for the folks watching at home to realize that these acts, while exciting to watch, are potentially life-threatening, limb-threatening and brain-threatening acts if an accident should occur."
Moore's injury is one of several at this year's Winter X Games. His younger brother, Colten, suffered a separated pelvis in the same event. Freestyle skier Rose Battersby, a New Zealander, incurred a spinal fracture, and Icelandic snowboarder Halldor Helgason suffered a concussion.
Sebastian Landry, a filmmaker who specialized in snowmobile features, told the New York Times last year that injuries in the sport made him lose interest in filming.
"It seemed like every time we went to the mountains somebody went to the hospital," Landry told the Times. "Kids get stars in their eyes and just want to go for it. That, plus being raised with the motor-head mentality where it's all or nothing."
It's not just the athletes who appear to be at risk.
During one of the jumps on Sunday night, Australian Jack Strong was attempting a backflip on his machine when it got away from him. The runaway snowmobile crashed into a bank of fans. A young boy who hit his knee on a parked vehicle while trying to get away was evaluated and released; other spectators avoided injury. Strong was not seriously injured.
ESPN, which organizes and televises the X Games, says it is constantly working to ensure the safety of competitors.
In a statement e-mailed to CNN, ESPN said, "Our thoughts and prayers are with Caleb (Moore) and his family. We've worked closely on safety issues with athletes, course designers and other experts for each of the 18 years of X Games. Still, when the world's best compete at the highest level in any sport, risks remain. Caleb is a four-time X Games medalist who fell short on his rotation on a move he has landed several times previously."
ESPN says the safety of fans also is a priority.
"We've worked closely with athletes, risk management specialists, sport organizers and event managers to ensure the safest possible conditions for athletes and spectators alike. Further measures are constantly being evaluated to ensure the safest possible experience for spectators."
One thing spectators won't experience: a drop-off of the X Games.
ESPN says it is expanding the Summer X Games to Munich, Germany; Barcelona, Spain; Foz do Iguacu, Brazil; and Los Angeles. The Winter X Games were expanded this year to include Aspen and Tignes, France.
"This is something that is truly valuable for sponsors, for ESPN, in terms of generating tens of millions of dollars of revenue, in terms of subscriber fees and advertising sales", says Lee Berke, president and CEO of LHB Sports, Entertainment & Media Inc.
Berke said that while ESPN did not win the U.S. rights to televise the Olympics, "they've gone about making the X Games their own Olympics."
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