Myth Busters: Does Your Core Need to Be Switched On All Day?

The Claim

A persistent piece of advice given to people with back pain is to keep their "core switched on" throughout the day — tensing the deep abdominal muscles during sitting, walking, and even standing still, on the theory that continuous bracing protects a vulnerable spine.

How the Trunk Normally Works

In a healthy, well-functioning system, trunk muscle activation is automatic and task-specific, not something requiring continuous conscious effort. Research on pre-programmed trunk muscle activity has shown that muscles such as transversus abdominis typically activate in a feedforward manner — fractions of a second before a limb movement, scaled appropriately to the anticipated demand — without any deliberate bracing instruction. The nervous system is, in other words, already doing this job constantly and largely outside conscious awareness, calibrating activation to the actual task rather than holding a flat, maximal contraction regardless of what the body is doing.

The Problem With Constant Conscious Bracing

Deliberately maintaining a braced core throughout ordinary daily activity creates several problems. It increases intra-abdominal pressure and overall metabolic cost for tasks that do not require it, it can interfere with normal, efficient automatic motor patterns by substituting conscious, effortful control for an already well-functioning automatic system, and in some clients it reinforces an underlying fear that the spine is fragile and needs to be constantly guarded against — a belief associated with poorer outcomes in chronic low back pain populations, independent of actual tissue status. Constant low-level bracing has also been associated with increased, rather than decreased, spinal loading in some biomechanical analyses, since co-contraction of opposing muscle groups increases compressive load on the spine.

When Deliberate Bracing Is Genuinely Useful

This is not an argument against bracing altogether — deliberate, momentary intra-abdominal pressure generation is a legitimate and useful strategy for specific, genuinely high-demand tasks: a maximal deadlift, an unexpected heavy lift, or a task performed in an unfamiliar or unstable position. The distinction is between appropriately dosed bracing for a specific, demanding task and the blanket instruction to hold the core "switched on" during ordinary sitting, walking or standing, where the automatic system is already managing the job perfectly well.

The Verdict