A winding rod for winding reels of web material, comprising: a longitudinal body extending from a first end to a second end, a plurality of expandable elements distributed around a longitudinal axis (A-A) of the longitudinal body; at least one pressurization circuit for expanding said expandable elements; wherein the expandable elements are distributed in a first group comprising a plurality of expandable elements, distributed around the axis (A-A) of the winding rod, and a second group comprising a plurality of expandable elements, distributed around the axis (A-A) of the winding rod; the expandable elements of the first group and of the second group being arranged in respective first and second end portions of the longitudinal body; wherein said longitudinal body comprises an intermediate portion devoid of expandable elements; and wherein the first end portion and the second end portion comprise each a plurality of housings for the respective plurality of expandable elements; characterized in that: the longitudinal body of the winding rod comprises: a first shaft and a second shaft; a tubular element placed between the first shaft and the second shaft and torsionally and axially constrained to said first shaft and said second shaft, so as to form said longitudinal body; wherein the first group of expandable elements is mounted on the first shaft and the second group of expandable elements is mounted on the second shaft; the first shaft and the second shaft are fitted respectively with a first longitudinal passage for a pressurization fluid and a second longitudinal passage for a pressurization fluid, said first longitudinal passage and said second longitudinal passage being fluidly coupled to the first group of expandable elements and the second group of expandable elements, respectively. a longitudinal body extending from a first end to a second end, a plurality of expandable elements distributed around a longitudinal axis (A-A) of the longitudinal body; at least one pressurization circuit for expanding said expandable elements; wherein the expandable elements are distributed in a first group comprising a plurality of expandable elements, distributed around the axis (A-A) of the winding rod, and a second group comprising a plurality of expandable elements, distributed around the axis (A-A) of the winding rod; the expandable elements of the first group and of the second group being arranged in respective first and second end portions of the longitudinal body; wherein said longitudinal body comprises an intermediate portion devoid of expandable elements; and wherein the first end portion and the second end portion comprise each a plurality of housings for the respective plurality of expandable elements; characterized in that: the longitudinal body of the winding rod comprises: a first shaft and a second shaft; a tubular element placed between the first shaft and the second shaft and torsionally and axially constrained to said first shaft and said second shaft, so as to form said longitudinal body; wherein the first group of expandable elements is mounted on the first shaft and the second group of expandable elements is mounted on the second shaft; the first shaft and the second shaft are fitted respectively with a first longitudinal passage for a pressurization fluid and a second longitudinal passage for a pressurization fluid, said first longitudinal passage and said second longitudinal passage being fluidly coupled to the first group of expandable elements and the second group of expandable elements, respectively. the longitudinal body of the winding rod comprises: a first shaft and a second shaft; a tubular element placed between the first shaft and the second shaft and torsionally and axially constrained to said first shaft and said second shaft, so as to form said longitudinal body; wherein the first group of expandable elements is mounted on the first shaft and the second group of expandable elements is mounted on the second shaft; the first shaft and the second shaft are fitted respectively with a first longitudinal passage for a pressurization fluid and a second longitudinal passage for a pressurization fluid, said first longitudinal passage and said second longitudinal passage being fluidly coupled to the first group of expandable elements and the second group of expandable elements, respectively.