Athletes typically ride about 7-8 stages, or until a break point in your blood lactate values has been distinguished. This break point area is known as your lactate threshold. You are said to have crossed lactate threshold when blood lactate concentration increases by at least 1 mmol/L in two consecutive stages.
Middle class. The middle class is a class of people in the middle of a social hierarchy. In Weberian socio-economic terms, the middle class is the broad group of people in contemporary society who fall socio-economically between the working class and upper class. The common measures of what constitutes middle class vary significantly among cultures. A sizable and healthy middle-class can be viewed as a characteristic of a healthy society.
The Shrinking American Middle Class. The middle class, if defined as households making between $35,000 and $100,000 a year, shrank in the final decades of the 20th century. For a welcome reason, though: More Americans moved up into what might be considered the upper middle class or the affluent.