What is postural tone?

• A. Voluntary muscle contraction during movement
• B. Active reflex arcs only when needed
• C. Constant maximal contraction
• D. Resting activation of muscles to keep body upright against gravity

Answer: (D)

Postural tone is the steady, low-level activation of muscles that keeps the body upright and balanced against gravity, even when you’re not actively moving. It isn’t about deliberate, voluntary contractions for a task, and it isn’t solely from reflexes. Instead, it’s a continuous baseline muscle activity that maintains alignment and provides a stable platform for movement, allowing quick adjustments when you start to sway. It’s not a maximal contraction—tone is about a ready, relaxed level of activation, not grinding force. This baseline activation is what keeps you upright: the trunk, neck, and limb muscles maintain posture so your body stays aligned and can respond to perturbations. Abnormalities in postural tone can lead to either too much resistance to movement (hypertonia) or too little support (hypotonia), affecting balance and posture.