Whether in the context of a sport practice or of a daily use, people tend to tighten the shoelaces of their shoes too much in particular in order to feel an accentuate holding of the foot. Furthermore, during a physical effort, such as running or walking, the foot swells naturally inside the shoe, by blood inflow, and the foot therefore becomes tightened too much by the shoelace.
Still, shoelaces tightened too much on a foot, whether because of a too strong initial tightening or because of a subsequent swelling of the foot, result in numerous annoyances.
The compression of the foot by a shoelace tightened too much may result in a compression of the blood and nerve vessels, with several negative consequences: heavy legs sensations, pins and needles sensations, tingling, pains at the calves, cramps, tears, sprains or contractures.
Furthermore, a shoelace tightened too much also prevents the foot arches from moving freely and results in hindering the movement of the foot during an activity.
In addition, a too tightened shoelace tends to rigidify the shoe, with as a potential consequence a Morton neuroma. This neuroma, also called the «Morton's disease», is a very painful affection which touches the interdigital nerve of the foot because of a too tightened foot.
In the shoelaces field are known the fabric-made shoelaces, for example made of polyester, nylon, cotton or linen, as known from the document U.S. Pat. No. 696,440, and the rubber-made shoelaces.
The first example of a fabric-made shoelace barely offers comfort for the foot. Indeed, throughout the day, or during a sport activity, the pressure of the foot increases, and the rigidity of the shoelace will make its support unpleasant and above all generating compression marks on the top-side of the foot, called the «instep».
The second example of a rubber-made shoelace has the drawback of compressing the foot too strongly because of a too high elastic return. Indeed, because of its elasticity, the carrier will tend to tighten too much his rubber-made shoelaces which will strongly compress the foot in the shoe.
The state of the art is also illustrated by the teaching of document U.S. 2006/0168785 which discloses a shoelace comprising an elastic core, in particular made of silicone, wrapped inside with a sheath made of a plastic material, paper, a fabric or elastic, and a friction element associated to the sheath. Particularly because of the presence of the sheath and the friction element, this shoelace has the same defects as the two aforementioned shoelaces, and thus does not offers comfort and holding adapted to avoid the problems of over-compression of the foot.