Four-bar linkage stretching exercise apparatus

Abstract

A four-bar linkage stretching exercise apparatus includes four bars, four torsion springs, and two handles. Each of the four bars has two U-shaped yokes provided respectively at two ends thereof. The four bars are pivotably interconnected by one of the two U-shaped yokes of one of the bars coupled with one of the two U-shaped yokes of the bar by pivots to form a quadrangular body that is deformable. The handles are respectively mounted on the quadrangular body for holding by a user for applying an external force on the quadrangular body to deform the quadrangular body. The torsion springs are respectively mounted on the pivots for providing the quadrangular body a retaining force against the external force.

1 . A four-bar linkage stretching exercise apparatus comprising: 
 four bars each having two U-shaped yokes respectively provided at two ends thereof, each of said yokes having two opposite sides which have respectively a pivoting hole coaxially aligned with each other, said four bars being pivotably interconnected by one of said two U-shaped yokes of one of said bars coupled with one of said two U-shaped yokes of another said bar by inserting respectively a pivot into the pivoting holds of the corresponding yokes to construct a quadrangular body such that the quadrangular body is deformable;    holding means for holding by a user for applying an external force on the quadrangular body to deform the quadrangular body; and    resilient means for providing the quadrangular body a retaining force against the external force applied on the quadrangular body.    
   
   
       2 . The four-bar linkage stretching exercise apparatus as defined in  claim 1 , wherein each of said bars comprises an external tube and an internal tube, which are sleeved with each other and are adjustably fixed with each other by an adjustable screw threaded into the external tube and the internal tube to enable the length of said bars to be adjustable.  
   
   
       3 . The four-bar linkage stretching exercise apparatus as defined in  claim 1 , wherein said resilient means comprises four torsion springs mounted respectively on the pivots.  
   
   
       4 . The four-bar linkage stretching exercise apparatus as defined in  claim 1 , wherein said resilient means comprises four pulleys mounted respectively to the pivots that connect said U-shaped yokes, and a resilient endless rope fitted around at least two of said pulleys opposite to each other.  
   
   
       5 . The four-bar linkage stretching exercise apparatus as defined in  claim 1  further comprising a support frame connected to the quadrangular body, said support frame having a seat mounted thereon.  
   
   
       6 . The four-bar linkage stretching exercise apparatus as defined in  claim 5 , further comprising at least one roller mounted respectively below said pivots.  
   
   
       7 . The four-bar linkage stretching exercise apparatus as defined in  claim 5 , wherein said holding means comprises two support members mounted respectively to two of said pivots opposite to each other for resting of the user's legs, and a pressing member mounted to one of said pivots between the support members for holding by the user.  
   
   
       8 . The four-bar linkage stretching exercise apparatus as defined in  claim 5 , wherein said holding means comprises two handles mounted respectively to two of said pivots opposite to each other, and a pressing member mounted to one of said pivots between the two handles.  
   
   
       9 . The four-bar linkage stretching exercise apparatus as defined in  claim 1 , wherein said holding means comprises two handles mounted on the quadrangular body opposite to each other.  
   
   
       10 . The four-bar linkage stretching exercise apparatus as defined in  claim 1 , wherein said two handles are respectively mounted to two of said pivots opposite to each other.