How Does the "Balloon" Or "Canister" Model Explain the Core's Function?

How does the "balloon" or "canister" model explain the core's function?

The "balloon" or "canister" model describes the core as a 360-degree system of muscles that work together to regulate intra-abdominal pressure and support movement. This system includes the abdominal muscles, obliques, spine muscles, diaphragm (at the top), and pelvic floor (at the bottom). Rather than holding a static position, this system operates dynamically, allowing for simultaneous breathing and pressure regulation.

For example, during inhalation, the diaphragm descends while the pelvic floor elongates eccentrically, maintaining low-level activation to support the pressure system. During exhalation, both the diaphragm and pelvic floor rebound to maintain system integrity. This interplay allows for a seamless balance of mobility, stability, and efficient breathing, enabling the core to adapt to varying levels of demand—whether reaching, lifting moderate weights, or performing high-intensity movements. Breath-holding is generally discouraged in most activities because it freezes the diaphragm and disrupts this dynamic system, although it may have a role during maximal efforts.

This modern approach to core function highlights the importance of training the body as a coordinated, adaptable unit, focusing on mobility and dynamic control over static, rigid stabilization.

This Ask the Expert is an edited excerpt from the course, Optimizing Core Retraining, Part 1, by Jennifer Stone, PT, DPT, OCS, PHC, TPS, HLC.