Center of Pressure Posturography

Increased sway can indicate poor proprioceptive input, vestibular dysfunction, weak stabilizing muscles, or impaired central processing of sensory information. Conversely, very small sway is ideal. However, some sway is normal and necessary; the nervous system actively uses sway to sample sensory information and maintain balance. Moderate sway with small amplitude (stable) is healthier than rigid, immobile posture.

Vision provides powerful postural feedback. When eyes close, reliance shifts to proprioception and vestibular input. In healthy individuals, sway increases 40-100% with eyes closed but remains stable. In vestibular or proprioceptive deficits, eyes-closed sway increases disproportionately (>200%), revealing the deficit. This comparison (eyes open vs. closed) helps identify the source of balance problems.

CoP sway in laboratory testing correlates only modestly with real-world fall risk. Lab testing reflects quiet stance under controlled conditions, while falls occur during dynamic activities, distractions, and environmental perturbations. CoP testing detects balance deficits but should be combined with dynamic balance tests and functional assessments for better fall risk prediction.

CoP sway increases progressively with age, starting around 40 years and accelerating after 65. Older adults show larger sway area, longer sway path, and increased velocity. This reflects cumulative decline in proprioception, vestibular function, muscle strength, and processing speed. However, resistance training and balance exercise slow or partially reverse age-related increases in sway.

CoP analysis reveals postural control quality but only modestly predicts sport-specific balance or performance. Athletes in balance-demanding sports (gymnastics, surfing) typically show smaller sway, but training-specific improvements in sway may not transfer to dynamic sport performance. Use CoP testing alongside sport-specific balance and functional assessments.