New Method of Evaluating Muscular Strength of Lower Limb Using MEMS Acceleration and Gyro Sensors

The purpose of this study was to develop a home-use method of evaluating muscular strength of the lower limb of a physically diverse range of people. Through a survey of previous findings regarding the mechanical load of daily activities, we propose that rapidly standing from an initial low squat posture is an appropriate movement to evaluate muscular strength of the lower limb. Additionally, we define a new index of muscular strength of the lower limb called “muscular strength margin.” This index shows the muscular strength relative to the minimum required muscular strength for activities of daily living. For easy measurement in a home setting, we utilize Micro-Electro-Mechanical Systems (MEMS) acceleration and gyro sensors to measure muscle strength. The MEMS sensor method highly correlates (r = 0.996) with optical motion capture system method, indicating that the MEMS sensor method has sufficient reliability for home use. The validity of the method developed in this study was verified through kinematic and kinetic analyses of 98 subjects whose age ranged from 14 to 98 yrs and from data of previous studies.