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A longitudinal analysis of physical activity and overweight/obesity in adolescents in Saskatoon Hang Lai 1 , Nazeem Muhajarine 2 , Karen Chad 3 1, 2 Dept. of Community Health and Epidemiology, University of Saskatchewan; and 3 College of Kinesiology, University of Saskatchewan.
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A longitudinal analysis of physical activity and overweight/obesity in adolescents in Saskatoon Hang Lai1, Nazeem Muhajarine2, Karen Chad3 1, 2 Dept. of Community Health and Epidemiology, University of Saskatchewan; and 3 College of Kinesiology, University of Saskatchewan
Research Questions Methodology Results Discussion Implications Conclusion Outline
Research Questions 1) How do physical activity and overweight/obesity change over time in a cohort of adolescents in Saskatoon? Are there differences in the patterns of change in physical activity and overweight/obesity between boys and girls? 2) What are the effects of family/friends and physical environments on the changing patterns of physical activity in this sample?
Methodology: (1) Study sample • The data used in this study was taken from the in motion studies’ longitudinal data. • The target population comprised 835 adolescents from 12 to18 years of age • From seven schools in Saskatoon (Bedford Road: 325; Evan Hardy: 244; Egnatoff: 148; King George: 35; Caswell Hill: 39; Westmount: 15 and Mayfair: 29) • From six different school grade levels: grade 7 to grade 12 • In February 2003, the survey was distributed through the schools to students. • PA levels were assessed using the ‘My Physical Activity’ Questionnaire (Modifiable Activity Questionnaire for Adolescents - MAQ-A). The data collection was collected once per month from February to June 2003. • The ‘Factors Affecting My Physical Activity’ questionnaire was used to assess physical activity determinants. Data collection was collected in February and April 2003.
Methodology: (2) Outcome variable • The study outcome is Physical Activity, which is defined as high, moderate or low level. • KKD is used to assess physical activity level, defined as total daily energy expenditure (Kilocalories/kilogram of body weight/day – KKD). • Low PA (sedentary) <= 2 KKD • Moderate PA 2-8 KKD • High PA (enough physical >= 8 KKD activity to achieve health benefits)
Proportion of overweight/obesity by sex and age at Time 1 & Time 3
Final main effect model examining factors associated with High PA
Discussion (1) 1) Patterns of PA and overweight/obesity over time • Among adolescent girls those who were PA decreased over time during the school year; correspondingly proportion of girls overweight/obese increased over time. • Among adolescent boys, the pattern of change observed over the school year in overweight/obesity prevalence and PA levels were not dependent on each other. • With age, level of physical activity declined for both boys and girls. • Gender differences in PA were consistent: Adolescent girls were significantly less active than boys.
Discussion (2) 2) Determinants of changing PA patterns • Effects of Family & Friends • Adolescents who received greater direct support from family members were more likely to sustain their PA levels. • The more the family’s indirect support the less sustaining the adolescents’ PA were. • Friend’s support was not a significant variable in predicting adolescent PA over time. • Effects of Physical Environments • Home environment had a influence on sustaining physical activity among adolescent, and neighborhood environment had no impact on PA in adolescents in this study.
Implications • Health promotion efforts should be aimed at reducing gender disparities in PA: high priority should be placed on developing effective interventions for adolescent girls. • Interventions should be targeted to adolescent group to counter the decline in PA levels. • More research is needed to improve understanding about the reason and mechanism for the decline. • Family-based PA intervention program hold promise for long-term effectiveness Community actions should acknowledge the potential of families as PA promoting units, and the vital contributions of families to PA. • Households should be encouraged to provide safe spaces and facilities for physical activity that promote and enable adolescents and all family members to participate in and enjoy physical activities.
Conclusion • The current investigation confirms findings from previous studies: • Adolescent BMI increase with age, while PA decreased with age. • Boys were more likely to be active than girls. • Direct support from family and home environment had influence on sustaining physical activity among adolescents. • Contrary to some other studies, • Indirect support from family was contributed to decrease adolescents’ PA. • No association between friend’s support, neighborhood environment and adolescents’ PA were found in this study.
Acknowledgements • This research was supported by a grant from the Community and Population Health Research (CPHR) Training Program delivered by the Saskatchewan Population Health and Evaluation Research Unit (SPHERU). • I gratefully acknowledge the support of the CPHR Training Program in my presentation at the Conference.
