Patent ID: 8371994

Claim:
An adjustable spring device for walking and running for a user, comprising: (a) an upper lever and a lower lever having a predetermined shape; said lower level is mounted below said upper lever, and at least one of said levers is made of elastic material, each said lever has a front end and a rear end, said upper lever is attached to the user's footwear; (b) means for support of said levers, said means for support join said levers and function as a common fulcrum for said levers; (c) means for setting the means for support in different positions between said levers; (d) a first flexible link connecting the front ends of said levers and a second flexible link connecting the rear ends of said levers, said flexible links each has a respective length; and (e) means for adjusting the length of at least one of said flexible links; wherein the setting of said means for support in different positions between said levers allows for adjustment of the tension of said flexible links, thereby adjusting the spring device according to a particular style and a pattern of locomotion of the user.