¶ … patterns of physical activity and exercise indicates that there has been an overall trend of decreasing physical activity levels and increasing levels of inactivity among adolescents and adults (Gordon-Larsen, McMurray, & Popkin, 1999; Van Der Horst, Paw, Twisk, & Van Mechelen, 2007). Inactivity and poor diet are responsible a large number of deaths annually and could soon become one of the leading causes of death in developed countries. Research continues to reaffirm that there is a dose response relationship between physical activity and all causes of mortality. There is typically a risk reduction of around 30% for those attaining the recommended levels of at least moderately intense physical activity on most days of the week compared with those who are relatively inactive (Lee & Skerrett, 2001). Regular physical exercise has long been associated with decreased risk of fatal cardiovascular disease (Powell, Thompson, Caspersen, & Kenderick, 1987), obesity and diabetes (Knowler, Barrett-Connor, Fowler, Hamman, Lachin, Walker, & Nathan, 2002), all forms of cancer, (Wannamethee, Shaper, & Walker, 2001), and better psychosocial health (Lawlor & Hopker, 2001). But these studies have documented the benefits of moderate to vigorous exercise in adults on adult health. Childhood physical activity levels (e.g., physical exercise) have traditionally been presumed to influence later levels of activity as an adult (Kuth & Cooper, 1992). Do childhood experiences, particularly childhood and adolescent activity levels, influence later levels of activity and lower the risk factors for early manifestations of the aforementioned illnesses in adults? Childhood Activity Predicts Adult Activity Levels

In one of the earlier investigations of how childhood activity levels predict adult activity levels Dennison, Straus, Mellits, and Charney (1988) looked at how the physical activity levels of 453 men from 23 to 25 years of age compared with their physical fitness test scores when they were 10 to 11 or 15 to 18 years of age. The findings indicated that physically active adults displayed significantly better childhood physical fitness test scores than did the physically inactive adults. Half of the subjects had physical fitness test scores measured at both childhood and adolescent age levels and this relationship remained robust across all periods of measurement. Other predictors of childhood and adult activity levels included the subjects' reports of being encouraged by their parents to exercise when young, whether or not the subject had participated in organized sports after high school, and spousal encouragement of exercise. These findings suggested that strong social supports for exercise early in development and as an adult may predict patterns of adult activity. Educational level was also a solid predictor of adult activity levels such that more highly educated adults tended to exercise more often or be more physically active than lower educated adults.

One of the criticisms voiced concerning the above study is that childhood physical activity was indirectly measured by the child's score on standardized fitness measures and not by actual measurements or reports of activity levels in children and adolescents. This could present a potential bias in the findings as perhaps not all children scoring high on these fitness measures were actually more active than other children not scoring high and vice versa. Subsequent research has addressed this issue mostly by means utilizing self-report or other report measures of activity in children. For example, Kuh and Cooper (1992) investigated how self-reported childhood activity levels influenced adult activity levels on a stratified sample of 3500 men and women that were followed over period from birth until age 43. Findings indicated that both higher levels of childhood activity and being more practiced or comfortable with sports were associated with greater levels of activity in adults. Raitakan, Porkka, Taimela, Telama, Rasanen, and Vllkari (1994) drew on data from the Cardiovascular Risk in Young Finns Study. This study began in 1980 with cohorts of randomly sampled boys and girls ages 3, 6, 9, 12, 15, and 18 years-old being examined for the first in a series of repeated measurements. The measures were repeated in three-year increments when the subjects were age 24, 27, 30, 33, 36, and 39 years-old respectively. Physical activity was measured by means of a self-report questionnaire. The findings indicated that a high level of physical activity at ages 9 through age18, especially when it was continuous over these years, significantly predicted a higher level of adult physical activity.

These trends between childhood activity levels and adult activity levels have been consistent in the literature, but are not always replicated (Gordon-Larsen, McMurray, & Popkin, 1999). However, it is well-known that childhood physical activity declines...

These confounding factors may explain a great deal of the discrepant findings relating childhood activity levels to later adult levels of activity. In any event, the general trend supported by the majority of empirical evidence is that active children are more active as adults than are inactive children. There have been guidelines developed to determine the daily amounts of activity that would specify "active" versus "inactive" children and adults, there are also guidelines to determine optimum levels of activities such as television or video game use that would be designated sedentary activities that compete for children's exercise time. For instance, The Centers for Disease Control (CDC) and the American College of Sports Medicine recommend performing 30 minutes of moderate physical activity on most, if not all, days of the week (which translates to at least five days a week). In addition, the American Academy of Pediatrics Committee on Public Education recommend engaging in no more than two hours of television and/or computer/video gaming per day (American Academy of Pediatrics, 2001). Following these guidelines, Gordon-Larsen, Nelson, and Popkin (2007) investigated data from the National Longitudinal Study of Adolescent Health and found that a small proportion of subjects actually met the aforementioned CDC activity criteria of 30 minutes of activity most days of the week as children. There was also a strong trend for activity levels to decrease over all subjects as the subjects became older regardless of initial activity level. This trend became especially pronounced during the transition from adolescence to early adulthood (e.g., following graduation from high school) and was also markedly significant for females, more so for African-American and Hispanic females than for Caucasian females. Television viewing and video game playing tended to slightly increase over time for all subjects, but again those that initially engaged in less of these activities as children continued to engage in them less often as adults than subjects who engaged in them more often as children. The authors concluded that childhood activity levels were important in determining later activity levels and that the transition period from adolescence to adulthood is also a crucial time to promote the need to continue physical exercise.
In summary the research then does support a modest relationship between regular activity or exercise levels in children and adolescents and later adult levels of activity/exercise. The research also indicates that the level of physical activity in individuals declines from childhood and adolescence to adulthood for nearly everyone regardless of their childhood activity level. Because of this nearly global decline in activity levels there is also evidence that being inactive may have a stronger predictive relationship from childhood to adulthood than activity levels do; that is, being an inactive child is even more predictive of inactivity as an adult that the predictability of a physically active childhood is to a more active adulthood (Gordon-Larsen, Nelson, and Popkin, 2007; Ratakin et al., 1994; Rowland & Freedson, 1999). As stated previously there is a strong negative relationship between adult activity levels and early disease onset such that more active adults have less levels of early morbidity. There is also a strong relationship between childhood levels of exercise and child cardiac health (Ratakin et al., 1994), better overall health, less obesity, and better bone development (Gordon-Larsen, Adair, Nelson, & Popkin, 2004), and better psychological functioning such as less childhood depression and higher levels self-esteem in children who are active (Van Der Horst et. al., 2007). Thus, more active children grow up to become more active adults and as a group are less at risk to develop earlier manifestations of the aforementioned physical maladies, whereas inactive children should demonstrate the opposite association. Research has associated low activity levels in children and adolescence with a variety of adult behaviors including poorer diet, higher levels of tobacco and alcohol abuse, and a myriad of health issues (Pate, Heath, Dowda, & Trost, 1996). Given these relationships, it would also be fruitful to understand what specific personal and social factors are associated with higher and lower levels of childhood activity. Such information could serve as a method of increasing activity/exercise levels in inactive children and active children alike and perhaps could lead to better maintenance of activity levels in the transition to early adulthood.

Correlates of Childhood and Adolescent Activity Levels

There is a large body of research investigating the correlates of activity in children and adolescence. One of the most prevalent relationships is between…