Duo

Duo looks like inside zone but hits like power: the line generates vertical double teams at the point of attack — no puller, no sweep — and the back reads the linebackers, cutting off their reaction. Coaches call it 'power without the pull.' The concept is widely credited to legendary O-line coach Jim McNally, and it has become a staple of downhill run games at every level. For linemen it's the purest double-team assignment in football: move your man, keep four hands on him as long as possible, and climb late.

Defined by Coach Jay Freeman — 34 years coaching the offensive and defensive line.

Related trench terms

Double teamBoth sides

Two blockers on one defender — four hands, one man, moving him off the spot.

Combo blockO-Line

Two linemen briefly working together on a single defender before one releases to the next level.

Inside zoneO-Line

A run scheme where all blockers step playside, working combo blocks up to the linebackers.

PowerO-Line

A gap run scheme with a pulling guard and a lead blocker hitting downhill through the hole.

A gap (gap lettering)Both sides

The gap between center and guard — first letter in the gap-lettering system that names every hole up front.

Go deeper

• Coach Jay’s lineman training library — the technique behind the term →
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