A footwear of the present invention is provided with tank chambers which are disposed to be in contact with an instep, sole and ankle of the user for applying pressure thereto to protect his foot from shocks. The tank chambers are filled with air and air pressure within the tank chambers can be adjusted....http://www.google.co.uk/patents/US5230249?utm_source=gb-gplus-sharePatent US5230249 - Shoe or boot provided with tank chambers
