Iso (Isolation) is a man-blocking scheme that creates a one-on-one matchup between the fullback and the linebacker at the point of attack. It's pure downhill, north-south football.
Overview
Iso is the most straightforward run concept in football. Every offensive lineman blocks the defender in front of them while the fullback "isolates" the linebacker in the hole. The running back follows the fullback directly downhill.
The beauty of Iso is its simplicity. There are no pulls, no misdirection, no reads - just physical blocking and north-south running. The scheme creates a one-on-one matchup in the hole that the offense believes it can win.
While Iso has become less common in spread offenses without fullbacks, it remains a staple of power-running teams and is often used in short-yardage and goal-line situations. Modern variations may use tight ends or H-backs as the lead blocker.
History & Origin
The Isolation play is one of football's oldest concepts, dating back to the earliest days of the sport. It represents the purest form of power football - creating a lead blocker and running behind him.
Key Principles
- 1Man blocking up front - each lineman takes their man
- 2Fullback/H-back leads through the hole and blocks the linebacker
- 3Running back follows directly behind the lead blocker
- 4No misdirection or reads - pure downhill running
- 5Win the one-on-one matchup in the hole
- 6Physical, north-south running style
- 7Quick-hitting - ball is delivered fast
When to Use
Iso excels in short-yardage situations where you need guaranteed positive yards. It's effective when you have a physical fullback who can win his block and a downhill running back. Use it to establish dominance in the trenches.
Pros & Cons
Advantages
- +Simple execution for entire offense
- +Physical, reliable in short-yardage
- +Quick-hitting
- +Creates one-on-one matchup you can win
- +Sets up play-action
Disadvantages
- −Requires a fullback or capable lead blocker
- −Predictable - defense knows where it's going
- −No cutback opportunities
- −Can be stopped by a dominant middle linebacker
What Coaches Call It
Different coaches use different terminology for the same concepts.
| Coach | Team | Their Term | Notes |
|---|---|---|---|
| Bill Belichick | Patriots | Iso | Standard terminology |
| Mike Vrabel | Titans | Lead | Emphasizes the lead blocker |
| Kyle Shanahan | 49ers | Wham | When TE/H-back leads |
What You Need
Skills and jobs required to run this scheme effectively.
Critical
FB isos the play-side linebacker
Lead through hole and kick out defender. Physicality at the point of attack.
High
Create vertical seam for lead blocker
Drive defender inside to seal the gap. Fundamental power blocking technique.
Follow the lead blocker, run downhill
Make quick decision and hit hole decisively. Burst and decision-making.
Medium
Center IDs the ISO linebacker
Identify defensive front, communicate assignments to line. Mental quarterback of the OL.
Matchups
Good Against
- +Light boxes
- +Undersized linebackers
- +4-3 fronts
- +Defenses in passing situations
Avoid Against
- −Dominant middle linebackers
- −Heavy boxes
- −Stacked fronts
- −Two-gap defenses
Installation
What You Need
Prerequisites for running this scheme effectively.
- ✓Physical fullback who wins 1-on-1
- ✓Downhill running back
- ✓OL who can sustain blocks
When NOT to Use This
- !Don't call against elite MLB who will win the ISO block
- !Predictable if overused
- !No cutback - if hole is plugged, you're done