Background: Adolescent girls are insufficiently active to achieve health benefits.
As a result they have been targeted as a priority group for increasing physical activity
levels. However, physical activity interventions for this population have had limited
effect. A better understanding of the correlates of physical activity in adolescent girls
may better inform intervention design. Social support describes interactions,
resources, and assistance from others to influence physical activity behaviour. Social
support has been linked to physical activity in adolescent girls and could be a
modifiable correlate of physical activity. This thesis aimed to identify: (1) if there is
a positive association between social support and physical activity in adolescent
girls, and if so, (2) explore the potential pathways through which social support
influences behaviour.
Method: Firstly, a systematic review and meta-analysis was conducted to explore
the role of different providers (e.g. parents/friends) and types of social support (e.g.
emotional/instrumental) on adolescent girls’ physical activity, providing effect size
estimations for different combinations of associations. Secondly, an analysis of an 8-
week school based physical activity intervention for adolescent girls was conducted.
This involved a mediation analysis to examine: (1) if self-efficacy mediated
associations between social support and physical activity at baseline; and (2) if social
support or self-efficacy mediated the effectiveness of the intervention. Finally, a
qualitative study using constructivist grounded theory was conducted to investigate
the mechanisms through which social support influences physical activity behaviour
through conducting individual interviews with adolescent girls (n = 18).
Results: The systematic review and meta-analysis identified small but significant
positive associations between social support and physical activity in adolescent girls.
Similar magnitudes were identified for parent and friend support effect sizes. The
mediation analysis found that self-efficacy mediated the relationship between social
support and physical activity, however, social support did not mediate the
effectiveness of a physical activity intervention for adolescent girls. The results of
the grounded theory study suggest that social support can influence adolescent girls’
physical activity through enjoyment, self-efficacy, overcoming barriers to physical
activity, motivation, and performance improvements, as well as enabling physical
activity.
Conclusions: Whilst only small significant associations between social support
and physical activity in adolescent girls were identified, social support may also
indirectly influence physical activity through enjoyment, self-efficacy, overcoming
barriers, motivation, performance improvements and enabling physical activity.
There may be promise in targeting these constructs through social support behaviour
change strategies in physical activity interventions for adolescent girls