The annual Summer and Winter X Games bring together "extreme" athletes who compete in such sporting events as skateboarding, in-line skating, snowboarding, sky-surfing, sport-climbing, stunt bicycling, street luge, and barefoot water-ski jumping. The cable TV sports network ESPN developed the X Games and first broadcast them in the summer of 1995; the Winter X Games debuted in 1998. Touted as an alternative Olympics, the X Games cater to youth culture (the name is a convenient play on Generation X) and popularize athletic risk-taking. The X Games also commercialize and organize characteristically marginal and disorderly activities like skateboarding and skydiving, calling into question whether these increasingly mainstreamed sports can still be considered "extreme."

"Extreme" sports are those largely individualistic athletic activities that require people to push themselves "to the extreme," often by defying both gravity and society's standards for reasonable risk. Typically, extreme athletes also project an image that...