Understanding Run Fits In Football

Written By: Chris Haddad
Updated: February 12, 2024

The most important rule in stopping the run is to ensure all run fits/gaps are covered as a defensive. 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 when 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, allowing the defense to rally to the football.

To understand run fits, we first must understand gaps and techniques. If you’re unfamiliar with gaps and techniques, look at our most recent gaps and techniques article.

Defensive Football Run Fits

Run fits are the most important element on defense. If your team doesn’t understand how to stop the run, then you’re in trouble. Especially if you’re a defensive coordinator, you need to understand how to fix things when they break.

Every defensive scheme relies on run fit concepts and gap responsibility. Running backs run through gaps, if there are no gaps, then there is nowhere for the running back to run to. Defensive players need to know where they need to spill or contain the ball carrier, so they can all rally to the football.

All offensive formations present problems for the defense. To properly stop the ball carrier, teams must be disciplined in their gap responsibility and gap fit.

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 will be dissecting a simple 4-man line with 2 linebackers in the box. This is also known as the 4-2-5 defense.

gaps in football

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

The Mike (M) and Sam (S) linebackers are responsible for the other A and B gaps. Linebackers must be able to move with the line of scrimmage to maintain their gaps.

For instance, zone schemes, which have linemen 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 are assigned the “C” gaps. For any play that bounces to the outside, the defensive ends are often taught to force it back up inside toward the meat of the defense.

This is a similar structure to running a 4-3 defense as well.

2-Gap Run Fits

2 Gap run schemes are more difficult for the interior lineman but give 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 is playing a 2-gap technique that allows the linebacker behind him to scrape to the football without fighting over an offensive lineman.

This can be extremely useful if your linebacker is a pure ball hunter but doesn’t do well in a mess.

gaps in football

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, especially 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 by coaches who join the vIQtory Podcast). A pesky nose tackle can cause all sorts of trouble for teams who rely on the displacement of the A-gap run fit.

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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 aren’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!

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 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.

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 hands 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 linemen and two defensive ends. Even fronts have a variety of looks including over, under, and even looks.

Keep Learning

Football can be a complicated game. Teaching run fits is one of the hardest things to do as a coach. On top of teaching fits you’ll need to teach technique and fundamentals.

To help you, we’ve created courses where you can master your teachings of fundamentals.

Run fits in defense are often decided by the defensive coordinator.

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

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

About the author 

Chris Haddad

Chris Haddad is the founder of vIQtory Sports & high school coach for over 12+ years. He has been featured as an authority on Hudl, Bleacher Report and countless other football-centric platforms. Chris continues to study and provide valuable content for those looking to learn more about the game of football.