SEDENTARY BEHAVIOURS IN RELATION TO BODY-MASS-INDEX DEFINED EXCESS OF WEIGHT IN TEENAGERS LIVING IN A SMALL URBAN CENTRE OF SICILY, ITALY

Abstract

Introduction: Epidemiological studies indicate that sedentary behaviours are associated with obesity independently of physical activity. The aim of this study was to investigate the association of sedentary behaviours with excess of weight in a sample of children living in a smallest Sicilian town where several confounding factors could be presumed to play a limited role because of a very homogeneous daily lifestyle. Methods: The investigation involved a randomly selected sample of 100 pupils attending the first grade of secondary education school of a smallest town with 5,485 inhabitants. Sedentary behaviour was assessed by administering a questionnaire including questions about time spent on television and other screen-based entertainment in the week during school and vacation periods. Time spent in daily activities, such as sleeping and meals, and physical activity was also evaluated. Height and weight were measured by the interviewer, BMI was calculated and then categorized in two strata of over- and normal weight. Cross tabulation with chi-square statistics and a oneway analysis of variance (ANOVA) were used to evaluate the relationship between behaviours and BMI. Differences were considered significant at P ≤ 0.05. Results: The participants were between 11 and 16 years old (median age 13). Forty-three were female. Overall, 68 had a normal weight, whereas 20 were overweight and 12 obese. Normal and overweight subjects did not significantly differ by sleeping hours and time spent having meals, though those overweight were likely to spend less time at lunch and dinner than normal weight pupils (15 minutes or less vs. 30 or more). Similarly, the two BMI groups did not significantly differ by the average weekly hours they spent in physical activity during both school and vacation periods. Time spent in watching TV was also not significantly different during both periods. A strong positive relationship was observed only between BMI and other screen-based entertainment times (videogames, internet) during school period (normal vs overweight, weekly hours mean 3,64, SD 3.66 vs 6.12, SD 5,12, P = 0.01). Remarkable, but not significant, differences were detected between the same behaviours during the vacation period (normal vs overweight, weekly hours mean 6.15, SD 6.05 vs 9.64, SD 9.43, P = 0.08). Discussion: As a cross-sectional survey, the issue of causality direction remains unsolved and overweight could cause increased time spent in screen-based entertainment activities. However, it is interesting to observe that sedentary behaviours alone appear to be associated to differences in BMI within children and adolescent who were likely sharing most activities at school, such as mandatory physical education or artistic activities, but likely out school also, because of the secluded social setting. More effective public health recommendations should include limiting sedentary behaviours, not only promote physical activity.