Muscle training device

Abstract

A muscle training device includes a flat plate for a user to board and a main body that is attachable to, and detachable from, the flat plate. The main body includes a base portion, an elastic body provided on the base portion, and a string having a first end portion connected to the elastic body, and a second end portion positioned on a side opposite to the first end portion. The elastic body is configured to apply, to the string, an elastic force that acts against a tensile force when the second end portion is pulled.

What is claimed is: 
     
         1 . A muscle training device comprising:
 a flat plate for a user to board; and   a main body that is attachable to, and detachable from, the flat plate; wherein:   the main body includes
 a base portion, 
 an elastic body provided on the base portion, and 
 a string having a first end portion connected to the elastic body, and a second end portion positioned on a side opposite to the first end portion, and 
   the elastic body is configured to apply, to the string, an elastic force that acts against a tensile force when the second end portion is pulled.   
     
     
         2 . The muscle training device according to  claim 1 , wherein
 the main body includes two main bodies,   the flat plate includes a side portion extending in a direction between two end portions, and   the two main bodies are attachable to, and detachable from, the two end portions of the side portion, respectively, and a region of the flat plate other than the two end portions of the side portion is configured as a boarding region on which the user can board.   
     
     
         3 . The muscle training device according to  claim 1 , wherein
 the flat plate includes an attachment portion to which the main body is attachable,   the attachment portion includes a first plate arranged such that a gap is formed between the first plate and a surface of the flat plate,   the main body includes a second plate that is provided on a side of an outer surface of the base portion with a gap formed between the second plate and the outer surface, and   when the main body is slid with respect to the attachment portion of the flat plate, the second plate of the main body is configured to enter into the gap between the first plate and the surface of the flat plate to restrict separation of the main body from the attachment portion.   
     
     
         4 . The muscle training device according to  claim 3 , wherein
 the main body is configured to rotate with respect to the attachment portion so that the second plate of the main body enters into the gap between the first plate and the surface of the flat plate.   
     
     
         5 . A muscle training device comprising:
 a base portion;   two elastic bodies provided on the base portion; and   a string having a first end portion attached to one of the two elastic bodies, and a second end portion positioned on a side opposite to the first end portion;   wherein the two elastic bodies are configured to apply, to the string, an elastic force that acts against a tensile force when the second end portion is pulled.   
     
     
         6 . The muscle training device according to  claim 5 , further comprising a switching portion,
 wherein the two elastic bodies are a first spiral spring and a second spiral spring, respectively,   the switching portion is configured to switch between a first state in which only the first spiral spring generates the elastic force that acts against the tensile force, and a second state in which the first spiral spring and the second spiral spring generate the elastic force that acts against the tensile force,   the switching portion comprises a switching lever and a switching gear,   the switching gear is fixed to a shaft to which a center portion of the second spiral spring is fixed, and   in the second state, the switching lever is configured to engage with the switching gear such that the switching gear is non-rotatable, the center portion of the second spiral spring is non-rotatable, and the second spiral spring is windable, and   in the first state, the switching lever is configured to separate from the switching gear such that the switching gear is rotatable, the center portion of the second spiral spring, together with the shaft, is rotatable, and the second spiral spring is non-windable.   
     
     
         7 . The muscle training device according to  claim 5 , further comprising
 an emergency stop portion that is configured to stop the string from being pulled back towards the two elastic bodies in a state in which a force from a user is not acting on the string, and the string is pulled back towards the two elastic bodies due to the elastic force that is generated by the two elastic bodies and is applied to the string, wherein   the emergency stop portion comprises a rotating portion that is configured to rotate due to the elastic force, and a stopper portion that is configured to stop a rotation of the rotating portion,   the rotating portion comprises a protruding pin that is configured to protrude outside the rotating portion due to the rotation of the rotating portion caused by the elastic force, and   the stopper portion is configured to collide with the protruding pin that has protruded outside the rotating portion, to stop the rotation of the rotating portion and to stop the string from being pulled back.