Aerobic vs. Anaerobic. To understand the relationship between weights and calories, you need to know the difference between aerobic and anaerobic exercise. Sustained aerobic exercise, like steady jogging or cycling, is low intensity and can thus be done for a longer period of time.
absolute advantage. In the theory of international trade, a country or firm has an absolute advantage if it can produce a product (good or service) more 'efficiently' (cheaply) than others. First suggested by the UK economist Adam Smith (1723-90) as an extension of his division of labor doctrine. See also absolute cost advantage and competitive advantage.
Because the idea of comparative advantage is not immediately intuitive, the best way of presenting it seems to be with an explicit numerical example as provided by David Ricardo. Indeed some variation of Ricardo's example lives on in most international trade textbooks today. (See page 40-5 in this text).