Schoolbag load and relative weight among schoolchildren in Central Asia: a cross-sectional study from Uzbekistan

Abstract Excessive schoolbag weight has been associated with altered gait mechanics, postural adaptations, and increased risk of musculoskeletal discomfort in children. Although a 10% body weight (BW) threshold is widely recommended, no quantitative evidence exists for any Central Asian country. To quantify absolute and relative schoolbag load carriage across four school grades, to determine the proportion of pupils exceeding the 10% BW threshold, and to examine whether selected school-related routines are associated with exceeding it. A cross-sectional observational study was conducted among 108 pupils from four grade levels (Grades 1, 3, 5 and 7) in a single urban public school in Urgench, Uzbekistan. Schoolbags, including any additional bag carried, were weighed on five consecutive school days. Relative load was expressed as a percentage of body weight (%BW); the weekly mean (%BWavg) and the heaviest-day value (%BWmax) were computed for each pupil. Group differences were tested by one-way ANOVA with bootstrapping (1,000 replicates), with Games–Howell post-hoc comparisons. Relative load differed significantly across grades for both %BWmax ( F (3,104) = 9.94, p < .001, η 2 = 0.223) and %BWavg ( F (3,104) = 7.84, p < .001, η 2 = 0.184). The highest weekly mean relative load was carried by Grade 3 pupils (12.3%, SD 3.0), followed by Grade 5 (11.1%, SD 2.6) and Grade 1 (10.7%, SD 2.6); Grade 7 pupils carried the lowest (8.5%, SD 2.8). Post-hoc comparisons showed Grade 7 to be significantly lower than each of the three younger grades; the younger grades did not differ from one another. On their heaviest day, 96% of Grade 3, 92% of Grade 5, 70% of Grade 1 and 57% of Grade 7 pupils exceeded 10% BW. Absolute schoolbag mass rose steeply across grades (weekly mean 2.73 kg in Grade 1 to 4.52 kg in Grade 5; F (3,104) = 68.53, p < .001, η 2 = 0.664) while body mass doubled (26.5 kg to 53.2 kg). No differences were found by sex. In this single urban school, the decline in relative schoolbag load across the school years is driven by growth in body mass rather than by any reduction in the absolute load pupils are asked to carry. Relative load is high across the primary grades, with most pupils exceeding the 10% BW guideline on their heaviest day. These preliminary, single-site findings raise questions about the adequacy of a uniform, age-invariant 10% BW guideline and indicate the need for age-sensitive preventive strategies; confirmation in larger, multi-site samples is required before the results can inform national policy.