Exerciser for strengthening the grip of the hand and/or muscles of the forearm having a pair of handgrips or handles which are removably mounted on the arms of a helical torsion spring in a manner permitting the grips to be used interchangeably with springs having different strengths or resistances. The handgrips are fabricated at least in part of rubber or other rubberized material with longitudinally extending bores having resilient side walls configured for frictional engagement with spring arms of different diameters in a manner that permits rotational slippage of the handgrips about the spring arms and limits axial movement of the handgrips on the spring arms when the grip exerciser is in use and permits the handgrips to slide axially along the spring arms during installation and removal of the handgrips.