A cord comprises a braided sheath of strands having an outer surface, an inner surface, and a central hollow portion defined by the inner surface and having a volume and a core within the central hollow portion of the tubular braided sheath, such that when the cord is in a relaxed state the tubular braided sheath has a cylindrical shape and a relaxed volume of the central hollow portion wherein the core does not fill the relaxed volume of the central hollow portion of the tubular braided sheath； when the cord is in a longitudinal tensioned state, the tubular braided sheath elongates under the longitudinal tension such that a tensioned volume of at least a part of the central hollow portion of the tubular braided sheath is less than the relaxed volume； and the inner surface of the tubular braided sheath of tensioned volume contacts and cinches a surface of the core.
