Effect of urbanization on objectively measured physical activity levels, sedentary time, and indices of adiposity in Kenyan adolescents

BACKGROUND Urbanization affects lifestyles in the developing world but no studies have assessed the impact on objectively measured physical activity in children and adolescents from sub-Saharan Africa. PURPOSE To compare objectively measured habitual physical activity, sedentary time, and indices of adiposity in adolescents from rural and urban areas of Kenya. METHODS Physical activity and sedentary time were assessed by accelerometry for 5 consecutive days in 97 (50 female and 47 male) rural and 103 (52 female and 51 male) urban adolescents (mean age 13 ± 1 years). Body Mass Index (BMI) and BMI z-scores were used to assess adiposity. RESULTS Rural males spent more time in moderate-to-vigorous intensity physical activity (MVPA) compared with urban males (68 ± 22 vs. 50 ± 17 min, respectively; P < .001). Similarly, Rural females spent more time in MVPA compared with urban females (62 ± 20 vs. 37 ± 20 min, respectively; P < .001). Furthermore, there were significant differences in daily sedentary time between rural and urban subjects. Residence (rural vs. urban) significantly (P < .001) influenced BMI z-score (R(2) = .46). CONCLUSION Rural Kenyan adolescents are significantly more physically active (and less sedentary) and have lower indices of adiposity compared with urban adolescents and this is a likely reflection of the impact of urbanization on lifestyle in Kenya.