| CPC A43B 13/183 (2013.01) | 17 Claims | 

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               1. A spring device for a shoe for arrangement between an insole and an outsole, wherein the spring device comprises: 
            a lower outsole portion; and 
                an upper insole portion, 
                wherein the lower outsole portion and the upper insole portion are connected via a continuous roll portion having a curvature, 
                wherein the curvature comprises a continuously varying radius of curvature that increases towards the lower outsole portion according to a segment of at least one selected from the group of an elliptic or a parabolic curve, 
                wherein the continuous roll portion is positioned so that the wearer rolls over the continuous roll portion during step in heel running; and 
                wherein the upper insole portion comprises a plate, wherein the plate is substantially rigid so that the substantially rigid plate does not deform under load from the wearer. 
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