What is the Iso concept in 11v11 tackle football?
In 11v11 football an iso sends the fullback through the playside A-gap to block one linebacker one on one, while the line blocks down and doubles at the point of attack. The halfback runs off the fullback's outside hip and takes what is left. It is the only run in this playbook where a blocker leads into the hole rather than clearing a lane beside it.
Why Iso works in 11v11
It is the only run here with a blocker in front of the ball
Every other run on this site creates space beside the carrier: a sweep empties the edge, a zone scheme moves a front sideways, a trap lets a man through and hits him from the side. This one puts a fullback directly in the hole and asks him to win. That requires eleven players and a back in the backfield, and no smaller format on this site has either.
There is no read, and that is deliberate
The hole is named in the huddle and the back runs to it. Most missed yards in a young running game come from hesitation rather than from the defense, and a back who knows exactly where he is going arrives at full speed. It is the opposite design philosophy to outside zone, which is on the neighbouring page and asks him to decide.
It is how you take a linebacker's speed away
A fast linebacker who reads zone and runs to the ball is a hard problem for any play asking him to be wrong. Iso does not ask him to be wrong; it sends a man to him. Against a defense being quarterbacked by one player, this is often the only call that removes him rather than trying to out-guess him.
It removes every read from the runner
There is one hole, it is named in the huddle, and the back runs to it. That is worth more than it sounds with young or inexperienced players, because most missed yards in a running game come from hesitation rather than from the defense. A back who knows exactly where he is going hits the line at full speed.
It answers a linebacker who is beating you with movement
A fast linebacker who reads zone schemes and runs to the ball is a hard problem for a play that asks him to be wrong. Iso does not ask him to be wrong. It sends a blocker straight to him and takes his speed out of the equation, which is often the only way to stop a defense being quarterbacked by one man.
It sets up everything that fakes it
A defense that has been hit downhill starts filling downhill, and the moment it does, play-action and any misdirection off the same backfield action become far more dangerous. The iso is frequently worth more for the two plays after it than for the yards it gains itself.
How to read it
- 1
The fullback picks a shoulder and commits
He is not looking for someone to hit, he has been told who. Taking the linebacker's outside shoulder sends the ball inside him and taking the inside shoulder sends it outside, so the block itself decides where the run goes and the back reads it.
- 2
The back runs off the block, not around it
Tight to the fullback's hip. A halfback who gives himself room to see the hole has given the unblocked defenders room to reach it, and the only advantage this play has is that it arrives before they can.
- 3
Two yards is a success
This is not a call that is trying to break. It is trying to make the distance manageable and to make the defense play honest, and a back who bounces it looking for more has traded a certain two for a possible eight and a likely loss.
What changes in 11v11
It is the only run here with a blocker in front of the ball
Every other run on this site creates space beside the carrier: a sweep empties the edge, a zone scheme moves a front sideways, a trap lets a man through and hits him from the side. This one puts a fullback directly in the hole and asks him to win. That requires eleven players and a back in the backfield, and no smaller format on this site has either.
There is no read, and that is deliberate
The hole is named in the huddle and the back runs to it. Most missed yards in a young running game come from hesitation rather than from the defense, and a back who knows exactly where he is going arrives at full speed. It is the opposite design philosophy to outside zone, which is on the neighbouring page and asks him to decide.
It is how you take a linebacker's speed away
A fast linebacker who reads zone and runs to the ball is a hard problem for any play asking him to be wrong. Iso does not ask him to be wrong; it sends a man to him. Against a defense being quarterbacked by one player, this is often the only call that removes him rather than trying to out-guess him.
When not to call Iso
It does not exist without a fullback
The play is a lead blocker and a runner. Spread personnel with no back in the backfield cannot run it at all, which is a large part of why it has become less common: the same offenses that stopped carrying a fullback stopped having this call available.
A defense that outnumbers the box wins anyway
There is no read and no answer built in. If the defense has one more man near the line than the offense can account for, somebody is unblocked and arrives free, every single time. Against a loaded box the answer is to make them pay for loading it, not to run at it harder.
Take it to your team
Draw your plays in the football playmaker, collect them in the playbook maker, and print football play cards so every player knows them come Saturday.
Open Iso in the designer
Opens this exact 11v11 diagram. Move anybody, change the depths, then save it to your playbook.
Open this play in the designerRelated questions
Do I need a fullback to run iso?
Which shoulder should the fullback take?
Can you run iso in flag football?
What do I do when they load the box?
Related guides
Coach Ray Carroll
Coaches 5v5 flag football from kindergarten through 7th grade in San Mateo and San Carlos, California, and built RC Football to design, teach and print the plays his own teams run.