This is Alex Lowe. Free climber and high altitude mountaineer.  A rare blend of sport climber and someone who climbed all (14) of the worlds 8,000+ meter mountains. A legend in the world of climbing.  He's gone now. 
Saw him train at the Incline athletic Club up at Lake Tahoe. He did pull ups as easily as you or I do push ups. Story goes that on some days he would do... get ready for it... 10 X 75 pull ups. 
Grab that picture and enlarge it. His body fat is substantially lower than anyone else mentioned.