| 摘要 |
A unique arrangement for leg extension jumpers consists of elastic members connecting movable extension tubes to guide tubes located at the front and rear of a foot platform. The foot platform is pivotally connected at its front to the front guide tube or tubes and at its rear to a support tube or tubes fixed to and extending above the rear guide tube or tubes. A leg strap is fixed to the top of the support tube or tubes. In one modification, a brace member pivoted to and extending between the lower ends of the front and rear extension tubes acts as a ground engaging member. In another modification, the brace member is pivoted to and extends between the bottom of the front guide tube and support tube. The pivoted structure forms a pivoted parallelogram which is normally held in rectangular configuration by the elastic members.
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