Understanding Run Fits In Football

As a defensive, the most important rule in stopping the run, is to ensure all run fits/gaps are covered. Creating a wall of defenders, will create a barrier for the running back with nowhere to run.

What is a run fit? A run fit is plugging a defensive lineman or a linebacker into a gap, to ensure the running back can’t run through it. Covering all gaps will create a wall for the running back, forcing them to bounce it to the outside or gain minimal yards.

Run fits are important because, as mentioned it forces the running back to bounce the football laterally. If the running back is moving side to side, he’s not gaining yards which allows the defense to rally to the football.

In order to understand run fits, we first must understand gaps and techniques. If you’re unfamiliar with gaps and techniques – take a look at our most recent gaps and techniques article.

Single Gap Run Fits

The single gap run fit is the most common type of run fit. It requires one defender to worry about 1 gap. The defensive line is often shaded toward the gap they control, along with the linebackers lining up in the gap they will control.

For our example below, we’re going to be dissecting a simple 4-man line, with 2 linebackers in the box.

Above is a simple over-front. We have a 3 technique on the outside shoulder of the guard and a nose that’s in a 1 technique on the outside shoulder of the center. The two interior lineman will hold down the B gap as well as the A Gap.

The Mike (M) and Sam (S) linebacker are responsible for the other A and B gaps. Linebackers must be able to move with the line of scrimmage in order to maintain their gaps. For instance zone schemes, which having lineman moving all in one direction, take their gaps with them as they move laterally.

The two defensive ends (E), are responsible for holding the edge and have been assigned the “C” gaps. Any play which bounces to the outside, the defensive ends are often taught to force it back up inside toward the meat of the defense.

2-Gap Run Fits

2 Gap run schemes are more difficult for the interior lineman, but gives much more flexibility to a defense.

The nose tackle in a 3-4 defense often plays a two-gap technique. This requires him to punch through the center and play both A-gaps. The nose playing a 2-gap techniques allows for the linebacker behind him to scrape to the football, without having to fight over an offensive lineman. This can be extremely useful if your linebacker is a pure ball hunter but doesn’t do well in the mess.

The defensive ends, lined up in 4i’s (inside shoulder of the tackle), will be responsible for the B gaps. This puts a tremendous amount of stress on zone teams who especially like inside zone. If the Nose can control the leverage of the center, plugging the play-side A gap, the linebackers are able to scrape freely to the play.

3-4 schemes tend to give teams the most trouble, blocking scheme wise (as noted from coaches who join the vIQtory Podcast). A pesky nose tackle can cause all sorts of trouble for teams who rely on displacement of the A-gap run fit.

Understanding Run Fits From An Offensive Perspective

Why is it important to understand run fits? A few reasons:

  • In order to win football games, teams need to control the line of scrimmage
  • Helps defeat defensive schemes
  • Understand what defensive coaches are trying to accomplish

Understanding run fits isn’t just for defensive purposes. If you’re an offensive coach, and you’ve made it this far in the article, we encourage you to keep reading!

In order to beat a defense, you need to understand how they operate from the offensive line to the secondary. As mentioned in our podcast from 12 year NFL veteran QB Sage Rosenfels:

Kyle Shanahan learned early in his career coverages and schemes from a defensive perspective. That’s why he’ll be successful in his career cause he understands the complete picture.

Certain run schemes are better against certain fronts and vice versa. As an offensive coach, find the weak link or best matchup in the front where a player has a tough time controlling a gap and exploit it.

Here is a great video by Jeff Reinebold on defensive run fits from a 3-4. For those who like video and learning how coaches at the next level teach it, this is a perfect example.


Run fits in a defense are often decided by the defensive coordinator. He made decide that a man option is best , or a gap option is best.

What typically dictates the call is the personnel on the field. A bigger player is able to handle controlling a man, and covering two gaps, then it’s best to play that type of defense.

Often times having gap run fits are the easiest way to clean up reads for both the defensive line and the linebackers. Gap run fits are also the easiest to teach as each player can visibly see what gap that they’re responsible for.

How do you teach run fits? Do you have any buzz words like “chase the gap” on zone plays? Let us know in the comment section below what your favorite ways to both teach and stop the run are.

Related Q & A

What Is A 2 Gap Player In Football?

A two gap is playing through one offensive lineman but controlling two gaps. Popular in 3-4 defenses or even fronts in the 4-3.

What Is An Odd Front?

An odd front typically has 3 players with their hand on the ground. 3-4 or 3-3-5 defenses utilize an odd (3 players) front to stop both the run and pass.

What Is An Even Front?

An even front is typically a 4 man front, which includes two interior lineman and two defensive ends. Even fronts have a variety of looks including, over, under and even looks.

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