One of the problems in assessing the prevalence of physical inactivity (and therefore the estimation of the PAR) is that it is difficult to define physical inactivity. Most of the time, physical inactivity is defined as ‘not reaching the guidelines for healthy physical activity’. However in the beginning of the 1990s, Cale & Almond (1992) [...]
The journey from childhood, through adolescence and into adulthood is accompanied by marked changes in body size. Although the timing and tempo of the maturational processes vary considerably from individual to individual and between the sexes, between the ages of 8 and 16 years the body mass of a typical boy increases by approximately 160%, [...]