Watch VoirFilms. As an avid endurance athlete and someone who is always seeking the next challenge, Justin Kinner was naturally drawn to the Grand Slam of Ultrarunning. The "Slam" is a series of four of the oldest 100-mile foot races in the United States. The Slam starts in Virginia at the Old Dominion 100, followed by the world-renowned Western States 100, just 21 days later in California.