The insole has a number of flexible bulges on a first major surface, and a number of protruding ribs on a second major surface. The projections of the bulges fall within the regions bounded by the ribs. The bulges and their underlying bounding ribs therefore form a number of chambers. The insole further contains a number of through holes positioned between the ends of at least two ribs. The insole further contains a larger heel bulge provided on the first major surface in the heel section, and a concave on the second major surface, which is conducted to the other chambers via at least a duct.