If you’ve trained with me, you’ve heard me say it a thousand times: “Squeeze the bar!” “Death grip!” “Screw your feet into the floor!” “Activate your lats!”
Maybe you thought I was just being dramatic. Maybe you wondered why I’m so obsessed with you squeezing things as hard as possible. But there’s actual science behind this coaching cue, and it’s one of the most powerful techniques you can use to immediately improve your lifts.
It’s called Sherrington’s Law of Irradiation, and understanding it will change how you approach every single exercise.
What Is Irradiation?
Here’s the simple version: when one muscle works really hard, it recruits neighbouring muscles to help out. And if those neighbouring muscles are already part of the movement, the hard-working muscle amplifies their strength.
Pavel Tsatsouline, a legendary strength coach, explains it perfectly with this demonstration:
“Make a tight fist. Where do you feel the tension? Your forearm and biceps, right? Even tighter! White knuckles! Do you feel your shoulder and even chest flexing too? When the demand for force increases, other muscles jump in on the action. Like a stone dropped in the water sends ripples across the surface, tension spreads (irradiates) from the muscle directly responsible for the job at hand towards others. The bigger the stone, the taller are the waves and the further they spread!”
Try it right now. Make a fist and squeeze as hard as you can. Feel how the tension travels up your arm and into your shoulder? That’s irradiation in action.
Why This Matters for Your Training
The Law of Irradiation states that a muscle working hard recruits neighbouring muscles, and if they’re already part of the action, it amplifies their strength. Not by cheating (like swinging your back during barbell curls), but by “cheering.” The neural impulses emitted by the contracting muscle reach other muscles and turn them on, like electric current starting a motor.
This is the reason I’m constantly cueing you to:
- Screw your feet into the floor during squats and deadlifts
- Squeeze the weights as hard as you can with your hands
- Squeeze your non-working fist during single-arm exercises
- Activate your lats in squats, bench presses, and deadlifts
- Create a death grip during loaded carries
We want to recruit as many muscles as possible in every exercise we perform, but we also want to use them to increase the proficiency of each lift. This improves overall strength and stability.
Real-World Applications
Let’s look at some specific examples:
Loaded Carries
When you’re performing farmers carries or suitcase carries, that death grip on the kettlebell or dumbbell isn’t just about not dropping the weight. Squeezing with maximum force activates your rotator cuff through irradiation. When you squeeze something with a death grip, the rotator cuff turns on, and as a result, the shoulder ‘packs’ itself. This can actually help with some shoulder issues and creates better stability throughout the entire movement.
Deadlifts and Squats
When you squeeze the bar as hard as possible and screw your feet into the floor, you’re not just getting a better grip. You’re creating full-body tension that stabilises your spine, activates your lats, engages your core, and makes you significantly stronger and safer under load.
Single-Arm Work
During single-arm rows or presses, squeezing your non-working fist creates tension that spreads across your body, stabilising your core and improving the quality of the working side’s movement.
Bench Press
Squeezing the dumbbells or barbell as hard as you can stabilises your shoulders and allows you to produce more force. The tension in your hands radiates outward, turning on your chest, shoulders, and triceps more effectively.
When It Becomes Essential
Understanding and demonstrating muscle irradiation is an essential component in quality movement patterning. But it becomes absolutely necessary when the load increases.
During lighter training phases, you might be able to get away with less-than-perfect tension. But when you’re lifting heavy weights during an intensification phase, creating and maintaining full-body tension through irradiation isn’t optional. It’s what keeps you safe and allows you to lift maximal loads.
How to Use This Today
The next time you’re in the gym, practice this technique:
- Before you lift, take a moment to create tension
- Squeeze your hands around whatever you’re holding with maximum force
- Actively engage the muscles around the working area
- Maintain that tension throughout the entire set
- Notice the difference in how stable and strong you feel
You’ll be amazed at how much stronger you become simply by creating more tension.
The Bottom Line
Your body is incredibly smart. When you create high levels of tension in one area, that tension spreads throughout your entire system, making you more stable, more powerful, and more efficient.
So the next time I tell you to squeeze something, know that I’m not just being picky. I’m helping you tap into your body’s natural ability to create strength through irradiation.
Squeeze everything. Your lifts will thank you.
