A camshaft (C1) for a multi-cylinder internal combustion engine with poppet valves, comprising a main body , which is rotatable with respect to a first rotation axis, a first disk and means for varying the timing of said first disk with respect to said main body ; wherein said main body is shaped so as to define a circuit for a pressurized fluid; wherein said camshaft (C1) comprises first thrust means and second thrust means , which are adapted to be operated by said pressurized fluid and translated along respective translation directions, said first and said second thrust means being adapted to engage, on thrust, a first counterpart and a second counterpart , respectively, of said first disk ; wherein the engagement on thrust of said first counterpart by said first thrust means and of said second counterpart by said second thrust means , respectively, results in said first disk being rotated with respect to a first rotation axis (R-R) in a first rotation direction and in a second rotation direction, respectively, opposed to said first rotation direction, and therefore, in the relative angle between said first disk and said main body being varied; wherein said main body comprises an internal cavity for collecting the pressurized fluid and a first pipe for conveying the pressurized fluid exiting said internal cavity towards said first thrust means and second thrust means , wherein a switch is housed in said first pipe , which is movable between a first position and a second position, and wherein, when said switch is in said first position, said second thrust means are operated by the pressurized fluid and engage, on thrust, said second counterpart , while when said switch is in said second position, said first thrust means are operated by the pressurized fluid and engage, on thrust, said first counterpart ; characterized in that said switch is translatable by centrifugal force along a radial direction to said first rotation axis depending on the angular speed of said main body . wherein said main body is shaped so as to define a circuit for a pressurized fluid; wherein said camshaft (C1) comprises first thrust means and second thrust means , which are adapted to be operated by said pressurized fluid and translated along respective translation directions, said first and said second thrust means being adapted to engage, on thrust, a first counterpart and a second counterpart , respectively, of said first disk ; wherein the engagement on thrust of said first counterpart by said first thrust means and of said second counterpart by said second thrust means , respectively, results in said first disk being rotated with respect to a first rotation axis (R-R) in a first rotation direction and in a second rotation direction, respectively, opposed to said first rotation direction, and therefore, in the relative angle between said first disk and said main body being varied; wherein said main body comprises an internal cavity for collecting the pressurized fluid and a first pipe for conveying the pressurized fluid exiting said internal cavity towards said first thrust means and second thrust means , wherein a switch is housed in said first pipe , which is movable between a first position and a second position, and wherein, when said switch is in said first position, said second thrust means are operated by the pressurized fluid and engage, on thrust, said second counterpart , while when said switch is in said second position, said first thrust means are operated by the pressurized fluid and engage, on thrust, said first counterpart ; characterized in that said switch is translatable by centrifugal force along a radial direction to said first rotation axis depending on the angular speed of said main body . <EOS>