Validation of a Portable Force Plate for Evaluating Postural Sway

Area of Science:

• Biomechanics
• Human Movement Science
• Rehabilitation Engineering

Background:

• Postural sway measurement is crucial for assessing physiological changes and group differences.
• Portable force plates are increasingly used, necessitating validation against established methods.
• Understanding the reliability and validity of portable systems is key for widespread adoption.

Purpose of the Study:

• To validate posturographic data from a portable force plate against an in-ground force plate using linear and nonlinear metrics.
• To assess the reliability and validity of portable force plate measurements under various sensory and perturbation conditions.

Main Methods:

• Twenty participants completed postural sway trials on both portable (Natus) and in-ground (Bertec) force plates.
• Trials included variations in foam perturbation and eye condition (open/closed).
• Linear (path length, range, root mean squares) and nonlinear (sample entropy, correlation dimensions) metrics were calculated from center of pressure data.

Main Results:

• Satisfactory overall reliability (ICC consistency) was found for both force plate systems across conditions.
• Generally good validity (ICC absolute agreement) was observed, though metric-specific differences emerged.
• Data filtering significantly impacted the agreement between the two plate types.

Conclusions:

• Both portable and in-ground force plates demonstrate satisfactory reliability for postural sway research.
• Portable force plates are validated as trusted tools for in-home data collection, especially for remote or at-risk populations.
• The choice of metrics and data filtering should be considered when comparing portable and in-ground force plate data.