INFLUENCE OF BONDINGS FOR THE LACING, BACKERS AND HEEL COUNTERS OF THE FOOTWEAR IN THE PRONOSUPINATION MOVEMENT IN RUNNING

Abstract

The relationship between the excessive pronosupination of the rearfoot and some of the injuries in runners has been widely described in the 1it.erature (Bates, Cavanagh, Clement, Nigg, Stacoff). In the same way, the influence of the midsole design and the material used for its construction in the pronosupinatlon movement of the font has been analyzed by different authors. Nevertheless, the influence of other elements as heel counters, backers and bondings for the lacing, in the upper vamp that covers the foot has not beer! enough studied. In order to determine the effect of the above mentioned elements some experiments have been developed with a group of 10 runners selected because of their tendency to excessive pronation. Seven prototypes of running shoes with identical characteristics referred to construction of midsole and sole, but presenting different elements in the upper vamp materials designed to control the pronosupination of the foot, were successively weared by each runner selected The experiences consisted of filming three consecutive running supports done on a treadmill at an speed of 8 miles per hour (12.8 Km per hour). The speed of filmation of the camera was fixed at 85 images per second. After digitizing the Images obtained and the processing of the data, with an specially designed software for that purpose, the following results were obtained: - the prototypes not including control systems in the upper vamp generate the higher levels of pronation and torsion during the contact - isolated use of external heel counters does not permit to assure a good control of the- pronation movement but, however, has a rigidizing effect reducing the torsion movement. - including a post in the internal face of the rearfoot joined to the external heel counter showed a great effectiveness i n the control of the pronation reducing the torsion movement. - the location of backers fort he bonding of the lacing helps to reduce the pronation movement without rigidizing excesivelly the shoe.