Sample characteristics (Table )
Gender-specific characteristics of the Palestinian and Israeli samples
There were noticeable ethnic differences for most socio-demographic characteristics, with the exception of age. Among men, higher proportions of Palestinians were married, had primary school education or less or were homemakers compared to Israelis, and a low proportion of Palestinian men defined themselves as secular compared to Jewish men. Among women, the majority of Palestinians were homemakers with only a small proportion reporting gainful employment; a higher proportion of Palestinians had primary school education or less compared to very low proportion of Israelis, and very small proportion of Palestinian women classified themselves as "secular" compared to Jewish women.
Table presents the energy expenditure (EE) levels of health enhancing physical activity by study groups. Among men a significant excess in EE among Palestinians was noted for moderate and vigorous intensity. By contrast, among women significant differences were noted only for vigorous activities, with Palestinian women reporting significantly lower MET-minutes than Israeli women, but no difference in total MVPA. The exclusion of household indoor chores and caring activities from the calculation of MVPA resulted in lower medians in all groups, but for Palestinian women this reduction was substantial resulting in the lowest level of MVPA, approximately one-third that of Israeli women. Within the Palestinian population strong gender disparity was evident, the MVPA of men being almost double that of women (1.7 fold) mostly due to high vigorous-intensity activity of Palestinian men, which was 20-fold higher than that of Palestinian women.
Energy expenditure levels (weighted) of health enhancing physical activity§ by gender and ethnicity
Domestic PA contributed the largest share among Palestinian women, far more than its share among Israeli women or among Palestinian and Israeli men (Figure ). The contribution of the transport domain to total MVPA was the lowest for Palestinian women; Palestinian women reported the lowest median MET-minutes spent on travel-related walking, equivalent to 45 min a week compared to 105 min by Palestinian men and 2 h or more in the Israeli population (Additional file 1
: Table S2a). Work was the main source of health-enhancing PA for Palestinian men compared to its share among Israeli men. The contribution of leisure-time MET-minutes to total MVPA was higher among Israeli men and women than among Palestinians men and women.
The contributions (%) of job, household, transport and leisure domains to total moderate/vigorous energy expenditure (MET-minutes*wk-1) by gender and ethnicity.
In the leisure domain, walking was the most prevalent mode of activity in all groups (data not shown), although a gender by ethnic interaction was evident; among men, a higher proportion of Palestinians than Israelis reported walking for exercise/recreation (53% vs 43%, p < 0.004) and their mean minutes of walking per week was higher (153 vs. 84 min/week, p = 0.002). This difference was offset by higher participation in other sports activities reported by Israelis compared to Palestinians (72 vs. 47 min per week, p < 0.0001), resulting in a nonsignificant difference in EE in the leisure domain. By contrast, among women, walking was less prevalent among Palestinians than Israelis (42% vs. 53%, p < 0.0001). The gender differences in walking levels among Palestinians were substantial: 11% more men walked for exercise than women (p = 0.0007) and on average men walked almost an hour (55 min) more per week than women.
Domain-specific adequate PA, leisure-time inactivity and all-domain insufficient PA
There were considerable gender disparities among Palestinian for most PA indicators (Figure ). A significantly lower proportion of Palestinian women than men achieved adequate PA at work/home or by transport. Although similar proportions of women and men achieved adequate leisure-time physical activity, inactivity at leisure (i.e., reporting no exercise) was higher among Palestinian women than men as was the prevalence of insufficient PA considering all domains or even more so without caring and domestic chores. By contrast, there were no gender differences among Israelis, except for adequate leisure- time PA and no leisure-time PA, which indicated that women were more active than men.
Ethnic and gender-specific estimates (%, weighted) of domain-specific adequate physical activity (PA), leisure-time inactivity and all-domain insufficient PA with all questionnaire items or excluding moderate household chores and caring.
Gender-specific ethnic differences in adequate PA are shown in Additional file 1
: Figure S2A. Among men, the proportion of Palestinians who were adequately active at work was significantly higher than Israelis, whereas in the transport domain a significant greater proportion of Israelis than Palestinians were adequately active. However, the prevalence of physical inactivity at leisure and insufficient all domain PA did not differ significantly (also after adjustment for socio-demographic differences; adjusted odds ratio (OR) = 0.76, 95% CI: 0.47-1.24).
Among women, a similar proportion of Palestinians and Israelis achieved adequate PA at work/home, but the proportions of Palestinian women classified at adequate PA at the transport and leisure domains were much lower than those reported for Israeli women. The prevalence of leisure-time inactivity and all-domain insufficient PA among Palestinian women was twice as high as that of Israelis, and almost triple the prevalence in Israeli women when indoor chores and caring were excluded (47% and 18%, p < 0.0001). After adjustment for socio-demographic differences, Palestinian women were twice as likely to be classified as being physically inactive by all domains as Israeli women (adjusted OR = 2.3, 95% CI: 1.3-3.8).
Correlates of inactive lifestyle among Palestinians and Israelis
None of the socio-demographic indicators were significantly associated with all-domain insufficient activity among Palestinian men (Table , row %) including after adjustment for the effect of all the covariates. Among Israeli men marginal associations were noted for marital status and religiosity; married men and non-orthodox or secular men were more inactive than non-married and orthodox Israelis. We note that education was not associated with PA in either group. Among Israeli, however, the adjusted prevalence of leisure-time physical inactivity was 50% lower (p < 0.05) for men with a high-school certificate or university education (data not shown).
Ethnic and gender-specific differences in socio-demographic correlates of all-domain insufficient PA without exclusion
Among Palestinian women there was a strong positive association of age with insufficient activity that was not evident in Israeli women (significant ethnic interaction). An association with marital status in Palestinian women did not persist after adjustment for age, whereas married Israeli women were significantly more inactive (significant ethnic interaction). Among Palestinian women there was a strong association between working status and educational level. Thus, after adjusting for the effect of the covariates, being a Palestinian housewife was significantly associated with a lower prevalence of insufficient activity compared to women in paid jobs, and women with university degrees were substantially less likely to be insufficiently active than women with less than high-school education. Israeli women showed no significant associations with these variables, and there was a significant ethnic interactions. Israeli orthodox women were significantly less inactive than the non-orthodox, similar to the trend seen for Israeli men, but not in Palestinian men or women.
In a combined model of Palestinian men and women (data not shown) there were significant gender disparities in the associations of all-domain insufficient PA with age and education (p ≤ 0.05 for the interactions). The prevalence of insufficient PA among middle-aged women was twice that of Palestinian men in the corresponding age group, while in the oldest age group it was almost three-fold that of men. The association between education and insufficient PA differed strongly at the highest education level, where university educated women were less inactive than men (p = 0.02 for the gender-by-education interaction). Palestinian women in paid jobs were more likely to be insufficiently active, whereas for men it was the reverse (p = 0.10 for interaction), most likely reflecting the type of work in which each gender engaged and the strong contribution of domestic chores among Palestinian housewives.
After excluding domestic indoor chores and caring activities from the calculation of insufficient PA (Additional file 1
: Table S3a), the associations between all covariates and this estimate remained the same among Palestinian men but substantial changes were noted in other groups. Palestinian housewives were more likely to be inactive than Palestinian women in paid job and the associations with age and education were attenuated. In the Israeli population the association between insufficient PA and marital status were enhanced in both genders; married Israelis were more likely to be inactive than non-cohabitating and an association with work status was evident (P
= 0.006). Further, orthodox Israelis were no longer more active than the non-orthodox or secular.