The present invention provides a portable device for enhancing circulation in a limb comprising at least one strap for encircling the limb, a motor and a mechanism driven by said motor for intermittently actuating a first transition from a relaxed state to a strained state of the strap and a second transition from the strained state to the relaxed state. The mechanism includes at least one energy storing element operatively disposed between the motor and the strap and at least one energy releasing mechanism coupling between the energy storing element and the strap. The energy releasing mechanism enables fast release of energy stored in said storing element and the use of the energy so released to effectuate at least one abrupt transition between said relaxed and strained states.