Concurrent validation of a magnetometer-based step counter in various walking surfaces.

Area of Science:

• Biomechanics
• Wearable technology
• Gait analysis

Background:

• Clinicians require simple methods for quantifying gait activity.
• Current methods may be complex or limited in scope.
• A reliable, easy-to-use gait assessment tool is needed.

Purpose of the Study:

• To develop and validate a quantitative gait assessment using only a shank-mounted magnetometer.
• To assess the reliability of this magnetometer-based system across different surfaces.

Main Methods:

• Twenty-five healthy volunteers participated.
• A magnetometer (MAG system) was placed on the right shank.
• Step counts were compared against two validated systems (StepWatch Activity Monitor and Force-Sensing Resistors) during varied activities (level walking, stairs, slopes).

Main Results:

• The MAG system showed high correlation (r>.83) with Force-Sensing Resistors across all surfaces.
• Bland-Altman analysis indicated a ±5% limit of agreement between MAG and FSR.
• MAG and StepWatch Activity Monitor showed good correlation (r=.85) on level surfaces, with ±5% agreement.

Conclusions:

• A single magnetometer provides accurate step counting on varied surfaces.
• The MAG method is robust, easy to use, and suitable for clinical applications.
• This technology facilitates analysis of long-term walking activity in daily life.