Initial insight into why physical activity may help prevent adolescent smoking uptake.
ABSTRACT INTRODUCTION: Whereas research supports the importance of regular physical activity to decrease the likelihood of smoking uptake, the mechanisms accounting for this relationship are poorly understood. We sought to determine whether the enjoyment or reward derived from physical activity is one mechanism underlying the relationship between smoking and physical activity. METHODS: The sample was composed of 1374 adolescents participating in a prospective longitudinal survey study of health behaviors. Variables were measured via self-report every six months for eight waves of data spanning four years. RESULTS: An associative processes latent growth curve model revealed a significant and negative indirect effect of baseline physical activity on baseline smoking through baseline physical activity reward (bindirect=-.18, z=-3.11, p=.002; 95% CI=-.29, -.07). Similarly, there was a significant and negative indirect effect of physical activity trend on smoking trend through physical activity reward trend (bindirect=-.16, z=-2.09, p=.04; 95% CI=-.30, -.01). The effect of physical activity on smoking at baseline and across time was completely mediated by physical activity reward. There was less support for the idea that smoking progression was associated with reduced physical activity reward and subsequent declines in physical activity. CONCLUSIONS: This study provides the first evidence implicating physical activity reward as one mechanism by which physical activity reduces the likelihood of adolescent smoking uptake. Smoking prevention interventions that promote physical activity and target physical activity enjoyment may have an important impact on adolescent smoking initiation and progression.
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ABSTRACT: The tracking of physical activity and its influence on selected coronary heart disease risk factors were studied in a 6-year (original survey in 1980, with follow-ups in 1983 and 1986) study of Finnish adolescents and young adults as part of the Cardiovascular Risk in Young Finns Study. The subjects in this analysis were aged 12, 15, and 18 years at baseline. Physical activity was assessed with a standardized questionnaire, and a sum index was derived from the product of intensity, frequency, and duration of leisure time physical activity. Complete data on physical activity index from each study year were available on 961 participants. Significant tracking of physical activity was observed with 3-year correlations of the index ranging from 0.35 to 0.54 in boys and from 0.33 to 0.39 in girls. Tracking was better in older age groups. Two groups of adolescents (active and sedentary groups) were formed at baseline according to high and low values of the index, respectively. Approximately 57% of those classified as inactive remained inactive after a 6-year follow-up. The corresponding value for active subjects was 44% (p < 0.01, active vs. inactive). The long-term effects of physically active and sedentary life-styles were studied by comparing groups of young adults who had remained active or inactive in every three examinations. Serum insulin and serum triglyceride concentrations were significantly lower in active young men. They had a more beneficial high density lipoprotein to total cholesterol ratio and thinner subscapular skinfolds. Among young women, significant differences were seen in adiposity (subscapular skinfold) and in serum triglyceride concentration. Physical activity was also related to less smoking in both sexes and, among young men, to lower consumption of saturated fatty acids and to higher polyunsaturated to saturated fatty acids ratio of the diet. In regression analyses adjusted for the 6-year change in obesity, smoking status, and diet, the change in physical activity was inversely associated with changes in serum insulin and triglycerides in boys. Independent association with triglycerides disappeared when insulin change was added to the model, suggesting that the effect may partly be mediated through insulin metabolism. The authors conclude that the level of physical activity tracks significantly from adolescence to young adulthood. Physical inactivity shows better tracking than does physical activity, and subjects who are constantly inactive express a less beneficial coronary risk profile compared with those who are constantly active.(ABSTRACT TRUNCATED AT 400 WORDS)American Journal of Epidemiology 09/1994; 140(3):195-205. · 4.98 Impact Factor
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ABSTRACT: To identify factors associated with changes in physical activity in adolescent girls at risk for sedentary lifestyles and obesity. A cohort study was performed with 201 high school girls recruited to participate in an evaluation study of a school-based obesity prevention physical education program. Three assessments were performed during an 8-month period. Associations between physical activity and a range of personal factors (self-acceptance, self-worth, athletic competence, body image, depressive mood, perceived benefits, enjoyment of physical activity, self-efficacy, and body mass index), behavioral factors (watching television and time constraints), and socioenvironmental factors (social support and costs/resources) were assessed. The 2 strongest and most consistent factors associated with change in physical activity were time constraints and support for physical activity from peers, parents, and teachers. Measures assessing self-perceptions, global (ie, self-worth) and specific to physical activity (ie, self-efficacy to be physically active), were also associated with change in physical activity. For example, a decrease of 2.0 U for an adolescent's perceived time constraints (possible range, 3.0-12.0 U) would be expected to lead to an increase of 53 minutes of moderate to vigorous physical activity per week (95% confidence interval, 33-72 minutes). An increase of 2.0 U in perceived support for physical activity (possible range, 3.0-12.0 U) would be expected to lead to an increase of 35 minutes of moderate to vigorous physical activity per week (95% confidence interval, 13-56 minutes). An increase of 3.0 U on the self-worth scale (possible range, 5.0-20.0 U) might be expected to lead to an increase of 19 minutes of moderate to vigorous physical activity per week (95% confidence interval, 0-40 minutes). The effectiveness of interventions aimed at increasing physical activity among adolescent girls might be enhanced by engaging support from friends, family, and caring adults; addressing real and perceived time constraints; and helping adolescent girls feel more confident about themselves and their ability to engage in physical activity.Archives of Pediatrics and Adolescent Medicine 09/2003; 157(8):803-10. · 4.25 Impact Factor
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ABSTRACT: The aim of this study was to investigate the degree to which genetic and environmental influences affect variation in adolescent exercise behavior. Data on regular leisure time exercise activities were analyzed in 8,355 adolescent twins, from three-age cohorts (13-14, 15-16, and 17-19 years). Exercise behavior was assessed with survey items about type of regular leisure time exercise, frequency, and duration of the activities. Participants were classified as sedentary, regular exercisers, or vigorous exercisers. The prevalence of moderate exercise behavior declined from age 13 to 19 years with a parallel increase in prevalence of sedentary behavior, whereas the prevalence of vigorous exercise behavior remained constant across age cohorts. Variation in exercise behavior was analyzed with genetic structural equation modeling employing a liability threshold model. Variation was largely accounted for by genetic factors (72% to 85% of the variance was explained by genetic factors), whereas shared environmental factors only accounted for a substantial part of the variation in girls aged 13-14 years (46%). We hypothesize that genetic effects on exercise ability may explain the high heritability of exercise behavior in this phase of life.International Journal of Pediatrics 01/2010; 2010:138345.