Potential urban–rural differences in cardiorespiratory fitness and BMI in Serbian schoolchildren

Cardiorespiratory fitness (CRF) represents an essential health-related physical fitness component most frequently assessed by Shuttle-run test (SRT). The aim of this study was to investigate potential differences in CRF between schoolchildren from urban and rural areas, with respect to their age and gender. Data for this part of study were derived from a broad national cross-sectional school-based study aimed to evaluate physical fitness and overweight/obesity prevalence. The study consisted of two parts: the pilot study that was conducted in national capital and vicinity and the national study that included schoolchildren from territory of Republic of Serbia. For the purpose of the pilot study, 2230 schoolchildren (boys n = 1163, girls n =1067, age 9 to 14 years) from urban (3) and rural primary schools (4) were included in the study. Afterwards, the study was expanded on the territory of the Republic of Serbia. For that purpose, 11607 primary schoolchildren (boys n = 5913 and girls n = 5694, age 9 to 14 years) from urban (n = 44) and rural schools (n = 54) were included in the study. All measurements were conducted during regular physical education classes. In addition to time in SRT, basic anthropometric measures were taken (body height (BH), body weight (BW) and body mass index (BMI)). Age, gender and school location interaction associated differences in SRT were examined. Schoolchildren living in the urban area of the national capital had significantly higher BH and BW than their rural peers (there was no difference in BMI between these groups). Regarding the SRT, it was gender- and age-dependent (p < 0.001). Rural schoolchildren had longer time on SRT than urban only in 3rd and 4th- grade (p < 0.001), while in higher grades no difference was observed. The results from the national study showed that urban schoolchildren from Republic of Serbia had higher BH, BW and BMI than their rural peers. Boys had better results in SRT which increased with age (p < 0.001). SRT data revealed that 3rd- grade schoolchildren (regardless of gender) from rural schools achieved better results than their urban peers, contrary to the results from 6th- and 7th- graders. Urban-rural differences in BMI were observed only for schoolchildren participating in the national study. Schoolchildren from rural area of the national capital generally had better cardiorespiratory fitness than their peers from urban area of the national capital, but those differences were mostly age and gender associated. The national study yielded results that were only partly similar to the results from the pilot study. CRF was strongly influenced by age and gender, while area of residence had small impact on CRF. Rural schoolchildren had better CRF in lower grades however due to potential influence of factors other than the area of residence (participation in organized physical activity, lifestyle, eating habits) urban schoolchildren had better levels of CRF in higher grades.