Dehydration is the excessive loss of fluids in the body. Low levels of calcium and potassium may also cause muscle cramps, since both minerals contribute to healthy muscle function. Low blood supply to your legs and feet can cause cramping in those areas when you exercise, walk, or participate in physical activities.
Physical properties of materials and systems can often be categorized as being either intensive or extensive quantities, according to how the property changes when the size (or extent) of the system changes. According to IUPAC, an intensive property is one whose magnitude is independent of the size of the system.
On the other hand, it is silly to think of the volume of your swimming pool as being a property at a point. It is a characteristic of the entire swimming pool and that makes it extensive. A particularly important type of intensive property is the specific property, which is always given on a unit mass basis. An example is specific volume, which has units of volume/mass, typically expressed as cubic feet per pound or cubic meters per kilogram.