Though children have less warming muscle mass than adults, they nevertheless sweat just as intensely in order to maintain an ideal body temperature of 37 degrees centigrade. This is why it is important that their long underwear provide special functionality, as does this futuristic-looking X-Bionic model. ExpansionRibs at elbow and knee maintain warmth at the joints by means of air channels, for example, even in bent position. Partial compressions on the upper thighs exert performance-enhancing pressure not on a planar surface, but through bars. The bars allow ventilation and let the sweat cool the blood.