Physical activity levels have also dramatically
decreased in the past several decades. It has been
estimated that less than half of US adults engaged in
recommended levels of physical activity in 2005 [5].
Levels of physical activity have also decreased in adolescents
[6]. There is less access to physical activity (fewer
sidewalks), less physical education in schools [7], and
more time is spent on sedentary behaviors such as television
watching, surfing the internet, and playing video
games [8]. The myriad advances in technology developed
over the past few decades have made many tasks more
efficient, but in the process have ultimately decreased the
number of calories expended (i.e., TV remote controls,
automatic garage door opener, etc.).