1. 1 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

2. 2 Outline Research QuestionsResearch Questions MethodologyMethodology ResultsResults DiscussionDiscussion ImplicationsImplications ConclusionConclusion

3. 3 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?

4. 4 Methodology: (1) Study sample The data used in this study was taken from the in motion studies’ longitudinal data.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 ageThe 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 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 From six different school grade levels: grade 7 to grade 12 In February 2003, the survey was distributed through the schools to students. 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. 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. The ‘Factors Affecting My Physical Activity’ questionnaire was used to assess physical activity determinants. Data collection was collected in February and April 2003.

5. 5 Methodology: (2) Outcome variable The study outcome is Physical Activity, which is defined as high, moderate or low level.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).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 KKDLow PA (sedentary)<= 2 KKD Moderate PA2-8 KKDModerate PA2-8 KKD High PA (enough physical >= 8 KKDHigh PA (enough physical >= 8 KKD activity to achieve health benefits)

6. 6 Results

7. 7 Factor analysis results

8. 8 Proportion of overweight/obesity by sex and age at Time 1 & Time 3

9. 9 Proportion of PA levels

10. 10 Distributions of PA levels by gender and age

11. 11 KKD distributions t = (-2.16/0.62) = -3.48 p < 0.01 t = (-1.37/0.51) = -2.69 p < 0.01 t = (-0.84/0.45) = -1.87 p < 0.05 t = (-0.6/0.5) = -1.19 p > 0.05 t = (-0.45/0.49) = -0.92 p > 0.05

12. 12 Final main effect model examining factors associated with High PA

13. 13 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 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.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.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.Gender differences in PA were consistent: Adolescent girls were significantly less active than boys.

14. 14 Discussion (2) 2) Determinants of changing PA patterns Effects of Family & FriendsEffects of Family & Friends Adolescents who received greater direct support from family members were more likely to sustain their PA levels.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.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.Friend’s support was not a significant variable in predicting adolescent PA over time. Effects of Physical EnvironmentsEffects 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.Home environment had a influence on sustaining physical activity among adolescent, and neighborhood environment had no impact on PA in adolescents in this study.

15. 15 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.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.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.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.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.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.

16. 16 Conclusion The current investigation confirms findings from previous studies:The current investigation confirms findings from previous studies: Adolescent BMI increase with age, while PA decreased with age.Adolescent BMI increase with age, while PA decreased with age. Boys were more likely to be active than girls.Boys were more likely to be active than girls. Direct support from family and home environment had influence on sustaining physical activity among adolescents.Direct support from family and home environment had influence on sustaining physical activity among adolescents. Contrary to some other studies,Contrary to some other studies, Indirect support from family was contributed to decrease adolescents’ PA.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.No association between friend’s support, neighborhood environment and adolescents’ PA were found in this study.

17. 17 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).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.I gratefully acknowledge the support of the CPHR Training Program in my presentation at the Conference.

18. 18 Questions?