The prevalence of overweight among adults, children and adolescents has increased markedly in the last three decades in developed countries [1
]. In New Zealand, over half of the adult population and almost one third of our children aged 5-14 years are overweight or obese [4
]. Given the negative health consequences associated with being overweight [6
], reducing the prevalence of overweight is justifiably a public health priority.
The high prevalence of obesity rates have been proposed to be related to various factors which promote high energy intake (eating) and sedentary behaviour, and decrease physical activity [7
]. With respect to physical activity, there has been particular interest in the activity levels among socially disadvantaged populations such as ethnic minority groups, low income households, and people living in highly deprived areas. Several international reviews have generally found a positive gradient between socio-economic status (SES) and physical activity; with greater levels of leisure-time or moderate-vigorous intensity physical activity in those at the top of the socio-economic strata compared to those at the bottom [8
]. Although lower recreational physical activity has been found in low SES neighbourhoods, racial and ethnic minorities are more likely to live in walkable neighbourhoods and walk for transportation [11
]. Data from the New Zealand Children's Nutrition Survey (CNS) found that those in the highest deprivation quintile were more likely to be in the highest activity quartile compared to those in the lowest deprivation quintile. These findings mimic adult and international data and are most likely due to increased periods of active transport (such as walking to and from school). However, closer examination of the CNS data showed children in the highest deprivation quintile were significantly less likely to be active after school (when children tend to participate in structured sport and recreation activities). Caution is required when interpreting any results that uses SES indicators given the array of different economic measures used (household income versus deprivation), the age of participants, and difficulties associated with self-reported physical activity measurement.
Processes driving the low levels of physical activity are multi-faceted and operate at various levels including individual, household, community and/or societal [12
]. Therefore, successful strategies for enhancing physical activity among disadvantaged populations could range from the micro- (e.g., individually targeted exercise programs) to macro-level (e.g., enhancing the built environment to encourage utilitarian and recreational physical activity) [7
]. Many of the efforts to improve physical activity levels have involved interventions targeted at individuals such as advice from a general practitioner, a group seminar or a targeted physical activity program [13
]. However, recent international evidence suggests that public health strategies focused on encouraging changes to individual behaviour have in isolation tended to be insufficient [7
]. It is increasingly appreciated that the role of the environment is pivotal in understanding the population-level decrease in energy expenditure. Thus, a strong case can be made for substantial and sustainable environmental initiatives that provide and make easier opportunities for physical activity. Of course advocating a successful public health agenda requires a robust evidence base, including a confident assessment of whether environmental interventions do influence physical activity.
The purpose of this paper is to appraise international and New Zealand-based research to examine the impact of environmental factors on inequalities in physical activity and related health outcomes. Our particular interest is whether enhancements to the built environment have potential for addressing physical activity-related health inequalities among Māori, Pacific and low income communities in New Zealand. We focus on two key environmental factors that relate to urban design: open (green) space and street connectivity. These factors were identified as part of a larger multi-phase research study as key factors for addressing low levels of physical activity among Māori, Pacific and low income communities in New Zealand. The larger study sought to identify key intervention areas to address food security and low levels of physical activity in the three target communities. Full details of this project are detailed elsewhere [14
] but in brief, we conducted literature reviews, focus groups, stakeholder workshops, and key informant interviews. Participants included members of affected communities, policy-makers, and academics. The research was informed by complexity theory [15
] and environmental perspectives of obesity causation [17
] which were used to identify key areas (control parameters) to intervene. Complexity theory recognises that social phenomena, such as nutrition and physical activity emerge from multifaceted systems with a large number of interacting elements rather than through a linear causal chain within the system. Complexity theory implies that broad changes are most likely to arise when interventions target highly linked elements of the system-the control parameters. The results of the study identified enhancing open space and connectivity as two key factors. Furthermore, green space and street connectivity are two of the most frequently researched built environmental variables. We argue that consideration of future interventions for improving physical activity should include evaluating the potential implications for inequalities in physical activity among disadvantaged groups. Whilst our focus is on New Zealand, our study will be of interest to researchers from other countries because, to our knowledge, no previous review has evaluated the evidence for whether the built environment can exert an influence on health inequalities. Of course, if there is convincing evidence to support a role for the built environment in shaping health inequalities then this assertion has important implications for policy makers tasked with addressing this important social policy concern. Health inequalities are not only unjust and ameliorable but a reduction in health inequalities has various benefits for all of society [18
]. Our study provides particular attention to three socially disadvantaged population groups in New Zealand: Māori (indigenous), Pacific, and low income communities. In New Zealand, Māori, Pacific and low income communities persistently have poorer health outcomes than European populations including all-cause mortality, the leading causes of death, most types of morbidity as well as unhealthy behaviours (e.g., smoking, and poor diet) [5