Indian Relay, dubbed "America's original extreme sport," has roots dating back centuries to horse stealing raids. Native Americans are keeping the dangerous and compelling racing tradition alive.

Horses honed skills such as running, jumping and pulling as humans bred ... blood around their bodies — their heart rate can go really high and still be safe,” said University of Connecticut ...

Horses honed skills such as running, jumping and pulling as humans bred ... blood around their bodies -- their heart rate can go really high and still be safe,” said University of Connecticut ...