Chest-developing exerciser

Abstract

An exercise machine includes a main shaft having a bottom end and a top end along a longitudinal direction is described. A rotatable element may be provided at the bottom end of the main shaft. A torsion resilient assembly can include a fixed torsion structure, a pivotable structure and an elastic element. The pivotable structure can pivot to deform the elastic element to induce a resilient torque force. An engagement frame may be rotatably mounted to the pivotable structure. User force may cause the rolling of the main shaft to change an angular relationship between the engagement frame and the main shaft to cause the pivotable structure to induce a resilient torque force for user exercising.

What is claimed is: 
     
         1 . An exercise machine comprising:
 a main shaft having a bottom end and a top end along a longitudinal direction;   a rotatable element provided at the bottom end of the main shaft, the rotatable element rotatable around an axis substantially transverse to the longitudinal direction, the rotatable element positioned to roll forward and backward across a surface;   handlebars affixed to the main shaft at the top end;   a torsion resilient assembly having a fixed torsion structure, a pivotable structure and an elastic element, the pivotable structure rotatable relative to the fixed torsion structure around a torsion axis, the elastic element arranged longitudinally along the torsion axis substantially transverse to the longitudinal direction of the main shaft, the fixed torsion structure fixated to the main shaft, wherein the pivotable structure pivots to deform the elastic element to induce a resilient torque force;   an engagement frame having a high end and a low end, the engagement frame rotatably mounted to the pivotable structure of the torsion resilient assembly via the high end, the engagement frame defined with an angular relationship with the main shaft around the torsion axis; and   a footrest rotatably affixed to the engagement frame at the low end, wherein user force applied via the handlebar and the footrest causes the rolling of the main shaft to change the angular relationship between the engagement frame and the main shaft, the change of the angular relationship to cause the pivotable structure to pivot to induce the resilient torque force for user exercising.   
     
     
         2 . The exercise machine of  claim 1 , wherein the two handlebars are affixed on two sides of the main shaft via the top end, the two sides defining a transverse direction to the longitudinal direction, the transverse direction substantially parallel to the axis of the rotatable element. 
     
     
         3 . The exercise machine of  claim 1 , wherein the engagement frame comprises:
 at least one support bar provided longitudinally between the high end and the low end, wherein each support bar rotatably coupled with the pivotable structure at the high end and wherein each support bar is rotatably coupled with the footrest at the low end.   
     
     
         4 . The assembly of  claim 1 , wherein the elastic element has a middle portion and two end portions longitudinally, wherein the fixed torsion structure has a sleeve element to house the middle portion of the elastic element and wherein the pivotable structure includes two cap elements separately housing the end portions of the elastic element. 
     
     
         5 . The assembly of  claim 4 , wherein cross section of outer surface of the elastic element is non-smoothly shaped, and wherein the sleeve element and the cap elements are shaped substantially conforming the non-smoothly shaped outer surface of the elastic element to facilitate twisting the elastic element for the resilience torque force. 
     
     
         6 . The assembly of  claim 5 , wherein the cross section is squarely shaped. 
     
     
         7 . The assembly of  claim 1 , wherein a central passage is defined longitudinally through the elastic element, wherein the torsion resilience assembly further comprises a pivot rod housed within the central passage, and wherein the torsion axis is defined along the pivot rod. 
     
     
         8 . The assembly of  claim 1 , wherein strength of the resilient torque force depends on a level of compression applied on the elastic element, the torsion resilience assembly further comprises:
 an adjustment control to configure the level of compression applied to the elastic element to allow varying of the strength of the resilient torque force.   
     
     
         9 . The assembly of  claim 1 , further comprising:
 a coupling structure to configurably affix the handlebars and the main shaft, wherein the coupling structure includes a pin insert to select one of a plurality of angular relationships between the handlebars and the main shaft.