Abstract: Improved sports footwear which includes an insert positioned at least in the heel region of a shoe, the insert including an elastically deformable cellular structure arranged within an elastically deformable air-impermeable casing provided with inner projections on opposing faces. The casing is pneumatically connected to controllable mechanism, rigid with the footwear, for varying the air pressure within the casing so as to modify the elastic characteristics of the insert. Each projection on one face thereof is connected to a face portion of an opposing projection.