Abstract P259: Multilevel Predictors of Physical Activity For Early, Mid, and Late Adolescent Girls
Authors: Young Deborah R , Saksvig Brit I , Wu Tong Tong , Zook Kathleen , Champaloux Steven , Li Xia 
Published: July 2021

Physical activity is critical for obesity prevention and maintenance of cardiovascular health. In order to effectively promote this behavior, we must understand predictors, including contextual ones, of adolescent physical activity and recognize that they may change throughout adolescence. Most previous studies of determinants of physical activity have only examined one level of variable (e.g., personal or psychosocial factors). This study examined potential determinants ranging from intrapersonal to spatial environmental variables. Three racial/ethnic diverse independent cross-sectional, randomly-selected participants from the Trial of Activity for Adolescent Girls (TAAG 2003-2005; 6 field sites; grade 6 and 8) and TAAG 2 (2009, Baltimore/Washington DC area; grade 11) provided 6 days of accelerometry data to assess physical activity. We used questionnaires to obtain demographic and psychosocial information, height, weight and triceps skinfold to assess body composition (individual and social level variables), interviews and surveys to obtain school-level data, and geographical information systems for neighborhood variables. Lasso selection was used to identify significant variables at individual and social levels. Mixed models (13 individual, 5 social, 15 school, 12 neighborhood level variables) were used to determine multilevel predictors of physical activity. Mean minutes of moderate to vigorous physical activity (MVPA) were 23.7±11.7 in 6th grade, 22.2±11.2 in 8th grade, and 20.1±11.8 in 11th grade. Results show that all four levels influence MVPA but change across grades. The factors that influence MVPA are different at 11th grade than 6th and 8th grades. For instance, percent body fat and social support from friends were not predictors at 11th grade. Only barriers to physical activity predicted MVPA at all grades. In conclusion, MVPA is a complex behavior with fluid, multi-level predictors that researchers must consider when planning interventions.

Multilevel predictors of MVPA among adolescent girls at 6th, 8th, and 11th grade

6
th
Grade 2003 All sites (n=1579)

8
th
grade 2005 All sites (n=3085)

11
th
Grade 2009 MD only (n=563)

Parameter (SE)
P value
Parameter (SE)
P value
Parameter (SE)
P value

White race
1.80 (1.02)
0.08
2.40 (0.68)
<0.01
0.43 (1.44)
0.76

Percent body fat
−0.16 (0.03)
<0.01
−0.11 (0.03)
<0.01
−0.04 (0.08)
0.58

Average time spent alone per week
0.05 (0.04)
0.21
0.08 (0.03)
<0.01
0.05 (0.06)
0.40

Physical activity enjoyment
−0.12 (0.06)
0.06
0.06 (0.05)
0.17
−0.25 (0.11)
0.02

Physical activity barriers
−0.14 (0.06)
0.01
−0.16 (0.04)
<0.01
−0.40 (0.10)
<0.01

Outcome expectancies
−0.01 (0.01)
0.04
−0.00 (0.00)
0.38
−0.02 (0.01)
0.11

Enjoyment of physical education
0.57 (0.28)
0.04
0.34 (0.19)
0.07
0.03 (0.41)
0.94

Depressive symptoms
0.05 (0.04)
0.21
0.05 (0.02)
0.04
0.02 (0.07)
0.81

Social support from friends
0.37 (0.12)
<0.01
0.20 (0.09)
0.03
0.36 (0.23)
0.11

% students passing standardized math
−0.11 (0.03)
<0.01
−0.07 (0.04)
0.07
0.33 (0.29)
0.27

Perceived access to recreational facilities
0.22 (0.10)
0.02
0.03 (0.16)
0.79
−0.00 (0.21)
0.97

Perceived sidewalk availability
0.05 (0.21)
0.80
−0.06 (0.15)
0.71
−1.49 (0.42)
<0.01

Perceived neighborhood safety
0.26 (0.26)
0.32
0.44 (0.18)
0.02
0.87 (0.46)
0.06

Distance to participant's school
−0.33 (0.17)
0.05
0.02 (0.10)
0.83
−0.41 (0.26)
0.12

Number of parks 1 mile from home
0.19 (0.12)
0.13
0.36 (0.09)
<0.01
0.10 (0.85)
0.90