What it is

In the I formation two running backs line up one behind the other, straight behind the quarterback, so the three players form a line like the letter I. The back in front is the fullback, and the one deepest is the tailback.

In a game

The fullback runs ahead of the tailback and blocks the first defender in the hole, and the tailback follows him. It is the classic power-running look, and it also hides the direction of the play, because both backs start in the middle.

More detail

Variations move the fullback a little to one side. A “strong I” shifts him toward the side with the tight end, while a “weak I” shifts him to the other side. Teams that keep the I formation as a base are usually built around a big offensive line and a physical running game.

Animated diagram

1. The fullback and the tailback stand one behind the other, straight behind the quarterback.
2. The quarterback hands the ball to the tailback, and the fullback runs ahead into the hole.
3. The fullback blocks the first defender he meets, and the tailback follows him through the gap.