Family support and ease of access link socio-economic status and sports club membership in adolescent girls : a mediation study

Background Much research has been conducted into the determinants of physical activity (PA) participation among adolescent girls. However, the more specific question of what are the determinants of particular forms of PA participation, such as the link between participation through a sports club, has not been investigated. Accordingly, the aim of this study was to investigate the relationships between participation in a sports club and socio-economic status (SES), access to facilities, and family and peer support, for female adolescents.

Methods A survey of 732 female adolescent school students (521 metropolitan, 211 non-metropolitan; 489 Year 7, 243 Year 11) was conducted. The survey included demographic information (living arrangements, ethnicity indicators, and indicators of SES such as parental education and employment status and locality); access to facilities; and family and peer support (travel, encouragement, watching, praise, joint participation). For each characteristic, sports club participants and non-participants were compared using chi-square tests. Multiple mediation analyses were used to investigate the role of access, family and peer support in the link between SES and sport participation.

Results There were significant associations (p<0.05) between sports club participation and: all demographic characteristics; all measures of family and peer support; and access to sport-related facilities. Highest levels of participation were associated with monolingual Australian-born families, with two parents, at least one of whom was well-educated, with both parents employed, and high levels of parental assistance, engagement and support. Participation in club sport among both younger and older adolescent girls was significantly positively associated with the SES of both their neighbourhoods and their households, particularly in metropolitan areas. These associations were most strongly mediated by family support and by access to facilities.

Conclusions To facilitate and promote greater participation in club sport among adolescent girls from low SES neighbourhoods and households, strategies should target modifiable determinants such as facility access and parental support. This will involve improving access to sports facilities and promoting, encouraging and assisting parents to provide support for their daughters’ participation in sport clubs.

Characterization of the MEK5-ERK5 module in human neutrophils and its relationship to ERK1/ERK2 in the chemotactic response

The role of the extracellular signal-regulated kinase (ERK) 1 and ERK2 in the neutrophil chemotactic response remains to be identified since a previously used specific inhibitor of MEK1 and MEK2, PD98059, that was used to provide evidence for a role of ERK1 and ERK2 in regulating chemotaxis, has recently been reported to also inhibit MEK5. This issue is made more critical by our present finding that human neutrophils express mitogen-activated protein (MAP) kinase/ERK kinase (MEK)5 and ERK5 (Big MAP kinase), and that their activities were stimulated by the bacterial tripeptide, formyl methionyl-leucyl-phenylalanine (fMLP). Dose response studies demonstrated a bell-shaped profile of fMLP-stimulated MEK5 and ERK5 activation, but this was left-shifted when compared with the profile of fMLP-stimulated chemotaxis. Kinetics studies demonstrated increases in kinase activity within 2 min, peaking at 3–5 min, and MEK5 activation was more persistent than that of ERK5. There were some similarities as well as differences in the pattern of activation between fMLP-stimulated ERK1 and ERK2, and MEK5-ERK5 activation. The up-regulation of MEK5-ERK5 activities was dependent on phosphatidylinositol 3-kinase. Studies with the recently described specific MEK inhibitor, PD184352, at concentrations that inhibited ERK1 and ERK2 but not ERK5 activity demonstrate that the ERK1 and ERK2 modules were involved in regulating fMLP-stimulated chemotaxis and chemokinesis. Our data suggest that the MEK5-ERK5 module is likely to regulate neutrophil responses at very low chemoattractant concentrations whereas at higher concentrations, a shift to the ERK1/ERK2 and p38 modules is apparent.