A system including: (A) a device including: (a) a platform having, on a topside, a receptacle adapted to receive atleast a portion of a bottom of a shoe or foot of the user, (b) a securingmechanism, associated with the receptacle； (c) at least one soleadapted to contact a ground surface； (d) a mechanism, at least partiallydisposed between, and operatively associated with, the soleand a bottom side of the platform, including: (i) a motor, for operativelyconnecting to a power source, and (ii) at least one thrustingelement, mechanically associated with, and activated by, the motor, thethrusting element adapted to move, when in thrusting mode,between the sole and the platform so as to apply an upward force against thebottom side of the platform, thereby changing a heightof at least a portion of the platform with respect to the sole； (B) a sensordevice including a sensor adapted to associate with a lowerlimb of the user, and to produce a data signal related to locomotion of theuser, and (C) a microprocessor, operatively connectedto the sensor and motor, the microprocessor adapted to: (i) receive locomotion-related information based on the data signal； (ii)process the locomotion-related information to make a determination of alocomotion phase of the user, and (iii) control a timing ofthe mechanism, based on the determination, to effect the changing of theheight during a swing phase of the locomotion of the user.
