ABSTRACT
Physical activity (PA) is a broad concept containing a variety of different human behaviors that share the common denominator of expected beneficial effects on mental and somatic health (1). Typically, daily PAs take up about 30% of total energy expenditure and reflect a mixture of obligatory activities related to transportation, work, or household chores and self-chosen PA behaviors including sports and exercise activities in leisure time. Objective measurements of daily PA in studies conducted in Europe and the US have confirmed the existence of large individual differences in activity levels (26, 27). These differences are observed in men and women alike, and persist after stratifying for age which is known to have a strong effect on average PA level (49).
