October 23, 2010 9:00 PM ET
The title is on the line tonight at UFC 121. Brock Lesnar tries to defend his UFC heavyweight championship against Cain Velasquez at the Honda Center in Anaheim, California. While Lesnar is a big heavyweight, Velasquez is not. He fights more like a lightweight than a big man, and is tremendously conditioned, as John Brenkus and the Sport Science team discovered.