· Elasticity Elasticity is a fundamental property by means of which floors can elastically deaden the impact force of the body during jumping and running, thereby providing a feeling of comfort to players. Optimum values of elasticity provide for rapid action and reduced muscular stress, whereas excessive elasticity values lead to a slowing down of action. Floors that are too hard floors cause muscles to tire quickly, thus increasing the risk of injury to ligaments. There are two types of elasticity: point elasticity and area elasticity. Point-elasticity is the elasticity of the materials comprising the overlay flooring. These materials are usually synthetic, soft and flexible surfaces which provide cushioning and shock absorption, and almost no impact energy return. The point-elasticity value must be the same over the entire floor, thus, where synthetic surfaces are concerned, the materials must have a consistent thickness and create a homogenous layer. Area-elasticity is the elasticity of the possible foundation (sub-floor), generally made up of a network of wooden joists, rendering a stiff yet flexible layer which provides energy return but little cushioning. Excessive deflection is to be avoided and elasticity must be constant over the entire surface (for example, elasticity must have the same value on the joists and in the area between the joists) Uniformity The surface of the playing area must be perfectly level, as unevenness may cause irregular bouncing of the ball and disturb
the practising of fast sports. In fact, if the foot senses superficial waviness, it may move less securely, impeding performance. · Shock absorption properties Shock absorption is the non-elastic absorbency of the impact forces of the body, due to the inner viscosity of materials. It measures the impact force absorbed by the floor as opposed to returning the energy force to the athlete. The more impact energy the floor absorbs, the less impact the athlete must absorb, thus providing greater comfort for the feet. This parameter therefore ensures the greatest comfort to the foot. Excessive shock absorption levels may render sporting action more difficult. · Deformation The buckling capacity depends on the elasticity, viscosity and thickness of the elastic layer and defines the overall deformation of the floor under a dynamic load. An excessive value reduces safety when putting down the foot, increasing the risk of sprains. · Superficial friction Superficial friction is extremely important and has optimum values which vary according to the different sports. In running, for example, maximum adherence between the foot and the floor is needed, whereas tennis requires a controlled slide. In any case, however, the foot must be able to rotate easily on the point of support without blocking or risk of spraining. To improve superficial friction, synthetic materials are embossed on the surface · Ball bounce The rebound of the ball is a very important factor in ball sports. The bounce must be uniform and regular over the entire surface. What is more, the flooring should not absorb the bounce to such an extent that it is impossible to play regular competitions on that surface. The International Basketball Federation’s regulations stipulate that the rebound height of a ball dropped onto the playing surface from a height of 1.80m must be at least 90% of the rebound height when dropped on a cement surface (1.20- 1.40m)
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