Layback, also known as shoulder external rotation, is one of the most important biomechanical factors in quarterback performance.
It directly affects:
And yet, most QBs have no idea how much layback they actually produce, or how to improve it safely.
At SpinLab, every QB receives a measured max ER (layback) value, allowing athletes and coaches to move beyond guesswork and train what actually matters.
In this guide, we’ll break down:
Layback is the amount of external rotation of the throwing shoulder.
In simple terms:
Elite QBs naturally achieve high layback without forcing it.
Developing QBs often struggle because of mobility restrictions, poor sequencing, or lack of shoulder strength.
Higher layback allows:
Counterintuitively, more layback (when controlled) is often safer than limited layback, because the arm can load and unload efficiently instead of muscling the ball.
Low layback is strongly associated with:
Layback is not just a shoulder issue.
It depends on mobility throughout the entire chain.
Your upper back must rotate and extend to allow the shoulder to externally rotate.
Restrictions here force the arm to compensate.
Key areas to improve:
If your upper back doesn’t move, your shoulder will take the load.
True layback occurs at the shoulder joint.
But forcing ER without control increases injury risk.
Mobility focus:
Mobility should feel smooth and not jammed or painful.
Tight lats and pecs restrict ER and pull the shoulder into a forward position.
This:
Addressing soft-tissue restrictions here often creates immediate improvements in max ER.
Mobility without strength is dangerous.
Elite QBs can control their layback.
Your rotator cuff must be strong enough to:
Weak ER strength leads to:
Strength training should target:
The scapula (shoulder blade) must move correctly to allow safe layback.
Poor scap control:
Strengthening the mid-back, lower traps, and serratus is critical for healthy layback.
Layback doesn’t just stress the arm going back,but it also stresses it on the way forward and through release.
Elite QBs have strong:
This allows them to throw hard without losing layback over time.
Many QBs chase layback with stretching alone and see no change.
Why?
Because layback depends on timing.
If:
…the shoulder never gets time to load.
Improving:
often increases layback without any additional stretching.
This is one of the biggest misconceptions in QB training.
Most QBs don’t know:
SpinLabAi measures max ER / max layback on every throw using only a phone camera.
This allows QBs to:
Instead of guessing, you train with objective feedback.
❌ Forcing the arm back manually
❌ Aggressive static stretching before throwing
❌ Ignoring thoracic mobility
❌ Training mobility without strength
❌ Chasing layback without fixing sequencing
❌ Assuming “more is always better”
Improving layback requires:
When done correctly, increased layback leads to:
And the safest way to improve it is to measure it, not guess.
With SpinLab, every QB knows their max ER and knows exactly how to train to improve it.
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