A system (10, 20, 400, 480, 590, 610, 660) to support a user's arm, including: a harness (404, 484) configured to be worn on a user's torso, the harness defining an axis vertical that extends generally parallel to the spine of the user wearing the harness, including the harness a shoulder harness (404, 484) configured to be worn on or around one or both shoulders of the user, and a torso bracket ( 416, 486, 612, 614) including a first end coupled to the shoulder harness and a second end configured to terminate next to the user's shoulder next to the arm being supported； an arm support coupled to the harness and including an armrest (120, 508, 674) configured to support a portion of a user's arm, the arm support including a shoulder bracket (106, 206, 618) pivotally coupled to the second end of the torso bracket such that the shoulder bracket is rotatable about a vertical pivot point (107, 207) generally parallel to the vertical axis and an arm bracket (108, 208, 624) pivotally coupled to the bracket of shoulder so that the arm bracket is rotatable around a horizontal pivot point generally orthogonal to the vertical axis without substantially interfering with the movement of the user's arm while the user's arm is supported by the armrest, the arm bracket supporting the armrest； and the system is characterized in that it also includes one or more compensation elements (112, 212, 500, 680) including a spring coupled to the shoulder bracket and the arm bracket to apply a torsional load to the arm bracket around the point of horizontal pivot to compensate at least partially a gravitational force that acts on the user's arm when the user moves and the arm support follows the user's movement.Un sistema (10, 20, 400, 480, 590, 610, 660) para soportar un brazo de un usuario, incluyendo: un arnés (404, 484) configurado para ser llevado en el torso de un usuario, definiendo el arnés un eje vertical que se extiende generalmente paralelo a la columna vertebral del usuario que ll
