Introducing Instability: The Secret to a Stronger, Safer Core

In this episode of Build for Health, Pete and trainer Srdjan Injac dig into what the “core” really is—and why it’s far more than the six-pack we’ve all been taught to chase. Srdjan breaks down the core as a 360-degree muscular system, not a single muscle group, and explains why abs alone represent only about 20% of what truly keeps us upright, stable, and injury-resistant. From the way sitting at a desk weakens deep stabilizers, to why most back pain comes from core fatigue rather than structural damage, Srdjan reframes core training as the foundation of long-term strength and mobility.

Together, they explore why machines shut off the core, why instability is your best friend, and how breathing and bracing are as essential as the exercises themselves. Srdjan walks through the muscles you never hear about—multifidus, transverse abdominals, pelvic floor—and explains how they work together to protect your spine, improve form in big lifts, and reduce fall and injury risk as we age. They also tackle myths, overrated exercises, and the mistake of thinking the core’s job is to move you. Its real job? Resist movement.

Whether you’re new to strength training or trying to understand why your lifts feel stuck, this conversation redefines what it means to “train your core” and how to build a body that supports you for decades to come.

Links & Notes

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