A tool (1) for physical training and rehabilitation, comprising a plurality of elastic rings (2a-2n) linked in succession to make an open chain (2); each of the elastic rings (2a-2n) is grippable with hands, or engageable by other parts of the body of the user (U), in such a way that the user (U) himself/herself can achieve the desired resistance to traction for the specific exercise to be executed in relation to the number of elastic rings (2a-2n) of said chain (2) actually placed under traction/extension. Each of the elastic rings (2a-2n) comprises at least a core (3) made of an elastic material and at least a covering (4) of the core (3) made of a material that is non-elastic with respect to the core (3), wherein the covering (4) is substantially configured as an accordion such that when the core (3) is not stressed under traction it has a large fitting on the core (3) itself, and when the core (3) is stressed under traction/extension the covering (4) is extended in order to conform to the extension of the core (3). The core (3) of each of the elastic rings (2a-2n) comprises at least one elongated elastic element (5), having two opposite ends (5a,5b), and at least one connection member (6) linked, or knotted, to the ends (5a,5b).