physical specimen
(n) : A person (commonly an athlete) with physical ability that cannot be gained through training. Those who are physical specimens break the mold for most athletes because they do exceptionally well under physically stressful or challenging situations and/or have more potential than others to be a world-class phenomenon in sports or on the battlefield.
Out of all of us, David is the fastest, strongest, and has the most endurance on the football team. He's a physical specimen.