Schoolbag Load and Relative Weight Among Schoolchildren in Central Asia: A Cross-sectional Study From Uzbekistan

Schoolbag Load and Relative Weight Among Schoolchildren in Central Asia: A Cross-sectional Study From Uzbekistan | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Schoolbag Load and Relative Weight Among Schoolchildren in Central Asia: A Cross-sectional Study From Uzbekistan Orifjon Saidmamatov, Allabergan Sharipov, Jasurbek Jammatov, Adilbek Atajanov, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9181546/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version 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 largely recommended, evidence from Central Asian countries remains limited. This study aimed to examine grade-level differences in relative schoolbag load carriage and to assess selected school-related lifestyle factors influencing load exposure among primary and lower secondary students in Uzbekistan. Methods: A cross-sectional observational study was conducted among 108 students from four grade levels (Grades 1, 3, 5, and 7) in an urban public school. Schoolbags were weighed daily across five consecutive school days of the week. Relative load was expressed as percentage of body weight (%BW). The average weekly load (%BWavg) and the heaviest-day load (%BWmax) were calculated. One-way ANOVA with bootstrapping (1,000 replicates) was used to analyze variations among school grades. Results: Significant grade-level variations with large effects were observed in both %BWmax (p<0.001, η²=0.483) and %BWavg (p<0.001, η²=0.635). Relative load decreased progressively over school grades. Grade 1 pupils carried the highest relative loads (mean %BWavg = 13.9%), with a substantial proportion exceeding 15–20% BW on the heaviest day. Conversely, older students were more likely to remain below the 10% threshold on weekly average measures. No significant variations were found based on sex. Conclusions: Younger pupils are disproportionately exposed to excessive relative schoolbag loads. These findings question the adequacy of a uniform 10% BW guideline across grades and highlight the need for age-sensitive preventive strategies in school settings. Health sciences/Health care Health sciences/Medical research Health sciences/Risk factors schoolbag load backpack weight children developmental differences musculoskeletal health Uzbekistan Introduction The transportation of heavy schoolbags by children has been largely recognized as a matter of concern among professionals involved in education, health care, and child well-being [ 1 , 2 ]. Backpacks, which are the most commonly used type of schoolbag, have been linked to several adverse musculoskeletal outcomes when overloaded, including alterations in spinal curvature [ 3 , 4 ], physical discomfort, and pain in the back and shoulder regions [ 5 – 8 ]. Importantly, musculoskeletal complaints such as back pain experienced during childhood and adolescence may persist over time and are considered predictors of back pain in adulthood [ 9 , 10 ]. Consequently, beyond its impact on health and quality of life, excessive schoolbag weight also represents an economic issue, as back pain constitutes a costly and widespread global health problem [ 11 ]. Alterations in walking mechanics and postural control have been documented when children carry loads exceeding 10% of their body weight [ 3 , 12 , 30 ]. However, even lower load levels may lead to adjustments in cervical alignment and changes in ground reaction forces [ 13 ]. Brackley et al. [14] argued that a recommended threshold of 10–15% of body weight is physiologically reasonable, taking into account factors such as maximal oxygen uptake, overall energy expenditure, cardiovascular responses, and tidal volume. Although no universally agreed-upon standard has been established, restricting schoolbag weight to 10% of body weight remains the most commonly cited guideline in the literature [ 3 – 5 , 7 , 13 , 15 – 17 ]. Despite these recommendations, many children continue to carry loads that exceed this suggested limit [1, 15, 18, 19]. Consequently, various recommendations have been developed to improve backpack load distribution [ 20 ], and alternative design solutions have been introduced to reduce mechanical strain [7, 21–24]. In addition, governments, professional organizations, and educational institutions worldwide have implemented initiatives aimed at mitigating the adverse health effects associated with heavy schoolbag carriage [ 1 , 7 ] and at identifying effective strategies to limit children’s exposure to excessive loads [ 25 ]. Several underlying determinants have been reported to influence schoolbag load carriage, including age [26], sex [16, 27], and body mass index (BMI) [ 5 ]. For example, research conducted in New Zealand demonstrated that younger pupils (third form) carried significantly heavier loads, averaging 7.0 kg (13.2% BW), compared with sixth-form primary school students, who carried 6.3 kg (10.3% BW) at approximately 11 years of age (p < 0.001) [26]. Similarly, in Northern California, girls from 5th to 12th grade were found to carry heavier loads (6.2 kg; 11.3% BW) than boys (5.8 kg; 9.9% BW) (p < 0.001) [ 16 ]. Evidence from Ireland further indicated that overweight children aged 9–11 years transported greater loads (5.0 kg) compared with peers of normal weight (4.7 kg) (p = 0.034) [ 5 ]. In addition, findings from a cross-sectional investigation conducted in Portugal revealed that younger students (grade 5) carried significantly greater relative loads than older students (grade 9), with a substantial difference in body-weight-normalized values (p < 0.001) [ 29 ]. Evidence from Asian countries also indicates that excessive schoolbag load carriage is a widespread concern among schoolchildren. Studies conducted in China and India have reported that students frequently carry schoolbags exceeding recommended weight limits, with younger students being disproportionately affected [31, 32]. Despite growing international concern regarding excessive schoolbag loads and their potential impact on children's musculoskeletal health, evidence from Central Asia remains extremely limited. To the best of our knowledge, no studies have specifically investigated schoolbag load carriage among schoolchildren in Uzbekistan and neighboring countries. This region may present unique contextual and environmental factors influencing schoolbag load carriage. In many schools, students are required to carry multiple textbooks and educational materials daily due to the absence of locker facilities. Furthermore, active commuting, such as walking to and from school, is common, which may increase the physical burden associated with schoolbag carriage. These contextual differences highlight the need for region-specific investigations. The aim of this study was to assess schoolbag load carriage and its relative weight in relation to students’ body mass across different school grades, as well as to examine the influence of selected school-related factors. Based on previous international evidence [5, 16, 26, 29], it was hypothesized that younger students would carry relatively heavier schoolbag loads compared with older students, and that school-related factors would significantly influence the relative schoolbag load carried by students. Methods Study design and setting This study was designed as a cross-sectional observational investigation conducted at an urban public school in Uzbekistan. Four school grades (1, 3, 5, and 7) were selected to gather insights on the changes in schoolbag load carriage over school years. Participants A total of 108 students from four school grades participated in this study (Grade 1: n = 23, including 12 boys and 11 girls; Grade 3: n = 24, including 12 boys and 12 girls; Grade 5: n = 38, including 22 boys and 16 girls; Grade 7: n = 23, including 8 boys and 15 girls). Participants were recruited using a convenience sampling approach from a public urban school located in Urgench, Uzbekistan. All eligible students enrolled in the selected school and meeting the inclusion criteria were invited to participate in the study. Inclusion criteria were as follows: (1) enrollment in a regular education program; (2) attendance at a public urban school; (3) full-time school attendance; (4) enrollment in Grade 1, Grade 3, Grade 5, or Grade 7 at the time of data collection; and (5) absence of diagnosed musculoskeletal disorders, chronic diseases, or other medical conditions that could influence schoolbag load carriage, as confirmed by school medical records. Exclusion criteria were as follows: (1) enrollment in special education programs; (2) attendance at private or rural schools; (3) part-time school attendance; (4) enrollment in grades other than Grade 1, Grade 3, Grade 5, or Grade 7; and (5) presence of diagnosed musculoskeletal disorders, chronic diseases, or other medical conditions that could affect schoolbag load carriage, based on school medical records. The study protocol was reviewed and approved by the 78/2 Ethical Committee of Mamun University (approval date: 28 November 2025). All procedures were conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from parents or legal guardians prior to participation, and verbal assent was obtained from all students. Data collection Lifestyle Several lifestyle school-related behaviors were recorded from each pupil, such as where do they have lunch (at home, at school canteen or at school brining the meal from home), the mode of transportation to school (walking, public transportation or private transportation), the features of the schoolbag (single stripe, two stripes or briefcase), Grade 1 and 3 pupils had one Physical Education lesson per week; whereas Grades 5 and 7, two lessons per week. Load carriage Data collection was carried out during five consecutive school days (Monday to Friday). Each student’s schoolbag was weighed once per day, resulting in repeated measurements for every participant. All measurements were performed in the morning upon arrival at school, before the beginning of classes. If students carried additional bags (e.g., sports bags), each bag was weighed separately, and the total carried load was calculated as the cumulative weight of all bags. All measurements were obtained using a portable digital luggage scale (OriGlam, Handheld Luggage Weight Scale, China) with a measurement precision of 0.05 kg. Schoolbags measurements were performed under standardized conditions, individually. The scale was calibrated prior to data collection in accordance with the manufacturer’s instructions. Anthropometrics Body mass was measured to the nearest 0.5 kg using a digital weighing scale (Artel ART-EB-1170, Artel Electronics LLC, Uzbekistan). Body height was measured to the nearest 0.5 cm using a floor-mounted mechanical medical stadiometer (R-Ss-MSK, Russia) with a maximum measurement range of 210 cm. Prior to data collection, the instruments were checked for proper functioning and calibrated according to the manufacturer’s instructions. All measurements were performed under standardized conditions, with students wearing light clothing and no footwear. Body mass index (BMI) was calculated as body mass divided by height squared (kg/m²). BMI classification was performed according to World Health Organization (WHO) reference standards. Schoolbag load was expressed relative percentage of body weight (%BW). It was computed the average relative load carried over the school week (%BWavg) and the day of heaviest load (%Bwmax). A schoolbag load exceeding 10% of the student’s body weight was deemed as excessive, in accordance with established international recommendations [14,18]. Statistical analysis Data is reported as mean ± 1 SD of absolute and relative frequencies. 95% confidence intervals are also stated. One-way analysis of variance for %BWavg and %BWmax were computed. Tukey was selected as post-hoc test. Data was bootstrapped for 1,000 successful replicates. Standardized effect sizes were calculated for both ANOVA by eta squared and for post-hoc testing by pairwise Cohen´s d. Eta squared interpretation was set as small (≤0.01), medium (0.06), or large (≥0.14). Cohen´s d was deemed as small (≤0.2), medium (0.5), or large (≥0.8). Statistical significance was set at p < 0.05. Thereafter, logistic regressions to learn what are the lifestyle school-related determinants (exogenous variables) that might lead pupils to carry overloads or a load within 10% of body weight (endogenous variable) were computed. To run an ANOVA one-way, assuming an effect size of 0.40, alpha error of 0.05, 90% power analyzing 4 school grades, the expected a priori sample size was 96 pupils (24 in each grade). Results Lifestyle Pupils from Grade 1 were more likely to have lunch at home (96%), whereas older counterparts from Grade 7 prefer to have at school canteen (83%, Table 1 ). Conversely, pupils from Grades 3 and 5 split up between those having at home and at the canteen. Hence, over time there is shift in the place where pupils have their lunch. As far as mode of transportation is concerned, most were choosing to walk. That said, a good portion of Grade 1 students (43%) were fetched on private transportation (i.e. family car). All students were carrying schoolbags with two stripes. Table 1 Sample characteristics and lifestyle. Gender Lunch place Mode of transportation Type of schoolbag Boys Girls total At Home n(%) At canteen n(%) Brought from home n(%) Walking n(%) Public transportation n(%) Private transportation n(%) One stripe n(%) Two stripes n(%) Briefcase n(%) Grade 1 12 11 23 22(96%) 1(4%) 0(0%) 12(52%) 1(4%) 10(43%) 0(0%) 23(100%) 0(0%) Grade 3 12 12 24 10(42%) 14(58%) 0(0%) 20(83%) 0(0%) 4(17%) 0(0%) 24(100%) 0(0%) Grade 5 22 16 38 17(45%) 21(55%) 0(0%) 35(92%) 0(0%) 3(8%) 0(0%) 38(100%) 0(0%) Grade 7 8 15 23 4(17%) 19(83%) 0(0%) 17(74%) 0(0%) 6(26%) 0(0%) 23(100%) 0(0%) Load carriage Referring to the day that pupils are carrying the heaviest load (Table 2 ), regardless of the BMI, 61% to 71% of Grade 1 pupils were carrying loads between 15% and 20% of the body weight. Most of Grade 3 and Grade 5 pupils were carrying 10 to 15% of the body weight (Grade 3: 56 to 88%; Grade 5: 89% to 94%). Interestingly, Grade 7 students were carrying 10–15% (38% to 57%) or even less (23% to 39%). As such, one can note that the percentage of body weight carried decreased over school years. That said, a close inspection to the average of all school days of the week (Table 2 ), 14% to 58% of Grade 1 pupils were carrying 10–15% of body weight or, 18% to 31% of 15–20% of body weight. In the other three school grades, pupils were more prone to carry mostly less than 10% of their body weight (Grade 3: 56% to 76%; Grade 5: 65% to 79%; Grade 7: 74% to 80%). Table 2 Load carriage normalized to body weight by all subjects and just pupils with normal body mass index. Load [in BW] Day of heaviest load All Days All pupils n(%) Normal BMI n(%) All pupils n(%) Normal BMI n(%) Grade 1 ≤ 10% 0(0%) 0(0%) 8(7%) 53(62%) > 10% & ≤15% 6(26%) 1(6%) 67(58%) 12(14%) > 15% & ≤20% 14(61%) 12(71%) 36(31%) 15(18%) > 20% 3(3%) 4(24%) 4(3%) 5(6%) Grade 3 ≤ 10% 1(4%) 1(6%) 67(56%) 68(76%) > 10% & ≤15% 21(88%) 10(56%) 50(42%) 15(17%) > 15% & ≤20% 1(4%) 1(6%) 2(2%) 1(1%) > 20% 1(4%) 6(33%) 1(1%) 6(7%) Grade 5 ≤ 10% 0(0%) 0(0%) 150(65%) 63(79%) > 10% & ≤15% 34(89%) 15(94%) 76(33%) 16(20%) > 15% & ≤20% 4(11%) 0(0%) 4(2%) 0(0%) > 20% 0(0%) 1(6%) 0(0%) 1(1%) Grade 7 ≤ 10% 9(39%) 3(23%) 85(74%) 52(80%) > 10% & ≤15% 13(57%) 5(38%) 29(25%) 8(12%) > 15% & ≤20% 1(4%) 1(8%) 1(1%) 1(2%) > 20% 0(0%) 4(31%) 0(0%) 4(6%) Effect of lifestyle school-determinants in load carriage School Grade. Analysis of variance of the heaviest load day [F(3,104) = 32.37, P < 0.001, η²=0.483] and the average load of all days [F(3,104) = 60.30, P < 0.001, η²=0.635] among school grades (Table 3 ) yielded significant variations with large effect sizes. Follow-up post-hoc test (Table 4 ) revealed that there were pairwise significant differences (0.001 < P < 0.2) with strong effect sizes between most school grades (0.881 < d < 3.611). All in all, the mean percentage of body weight carried decreased over school years. Only exception is comparing Grade 3 to Grade 5, where the pairwise comparison was not significant, with small effect sizes (0.833 < P < 0.940; 0.149 < d < 0.220). Interestingly, comparing Grade 5 to Grade 7 the pairwise was not significant (P = 0.073) but the effect size was medium (d = 0.649). Table 3 Analysis of variance of heaviest load day and the average load of all days among school grades. Grade Mean SD df F P η² 95CI η² Lower 95CI η² Upper Day of Heaviest load 1 0.165 0.025 3(104) 32.37 < .001 0.483 0.341 0.586 3 0.129 0.024 5 0.126 0.017 7 0.108 0.016 Average load of all days 1 0.139 0.021 3(104) 60.30 < .001 0.635 0.522 0.712 3 0.101 0.012 5 0.098 0.009 7 0.089 0.014 Table 4 Post-hoc test of the analysis of variance of heaviest load day and the average load of all days among school grades. Mean difference of bootstrapped medians 95 CI bootstrap SE df bias T Cohen's d 95 CI Cohen´s d P Lower Upper Lower Upper Day of heaviest load G1 v G3 0.036 0.022 0.048 0.007 104 -2.092×10 − 4 6.110 1.783 0.931 2.635 < .001 G1 v G5 0.039 0.029 0.052 0.006 104 -1.541×10 − 4 7.313 1.932 1.135 2.729 < .001 G1 v G7 0.056 0.047 0.071 0.006 104 -3.505×10 − 4 9.539 2.813 1.862 3.764 < .001 G3 v G5 0.003 -0.005 0.017 0.006 104 5.509×10 − 5 0.572 0.149 -0.553 0.851 .940 G3 v G7 0.021 0.011 0.035 0.006 104 -1.412×10 − 4 3.530 1.030 0.222 1.838 .003 G5 v G7 0.018 0.009 0.027 0.004 104 -1.963×10 − 4 3.334 0.881 0.151 1.610 .006 Average load of all days G1 v G3 0.038 0.030 0.049 0.005 104 3.686×10 − 5 9.394 2.741 1.804 3.678 < .001 G1 v G5 0.041 0.034 0.052 0.004 104 -1.932×10 − 5 11.209 2.961 2.061 3.861 < .001 G1 v G7 0.050 0.042 0.061 0.005 104 3.331×10 − 7 12.244 3.611 2.570 4.651 < .001 G3 v G5 0.003 -0.002 0.008 0.003 104 -5.618×10 − 5 0.844 0.220 -0.482 0.923 .833 G3 v G7 0.012 0.005 0.019 0.004 104 -3.653×10 − 5 2.980 0.869 0.068 1.671 .019 G5 v G7 0.009 0.002 0.015 0.003 104 1.965×10 − 5 2.458 0.649 -0.071 1.370 .073 Prospective determinants Logistic regression showed a non-significant relationship (R 2 Nagelkerke =0.065; P = 0.299). Hence unable to predict the reasons to carry loads greater or less than 10% of body weight on the day of heaviest load (Table 5 ). None of the exogenous variables selected (sex, BMI, lunch place, mode of transportation) showed significant relationship with the fact of pupils carrying overloads or a load up to 10% of body weight. However, there was a significant relationship (R 2 Nagelkerke =0.154; P = 0.01) and ability to predict correctly 62.96% of the observed cases of for the average of all days. The final model retained the lunch place (OR = 0.325; P = 0.007) and up to some extent the mode of transportation as determinants (OR = 1.625; P = 0.066). Sex and BMI did not play a significant role in carrying overload or a load up to 10% of BW. Table 5 Logistic regression models predicting the determinant lifestyle school-related factors determining if pupils carry overloads or a load within 10% of body weight. Wald Test 95% Confidence interval (odds ratio scale) Estimate Standard Error Odds Ratio z Wald Statistic df p Lower bound Upper bound Day of heaviest load Intercept 0.755 1.193 2.128 0.633 0.401 1 .527 0.205 22.044 Sex -0.193 0.532 0.825 -0.362 0.131 1 .717 0.291 2.339 BMI -0.353 0.400 0.703 -0.881 0.777 1 .378 0.321 1.539 Lunch Place -1.891 0.605 0.151 -3.123 9.756 1 .002 0.046 0.494 Mode of transportation 0.668 0.285 1.950 2.342 5.483 1 .019 1.115 3.409 Average load of all days Intercept 2.420 1.171 11.242 2.066 4.269 1 .039 1.132 111.618 Sex -0.286 0.461 0.751 -0.621 0.386 1 .534 0.304 1.853 BMI 0.167 0.347 1.182 0.482 0.232 1 .630 0.599 2.332 Lunch Place -0.820 0.476 0.440 -1.724 2.972 1 .085 0.173 1.119 Mode of transportation 0.224 0.312 1.251 0.717 0.514 1 .474 0.678 2.307 Discussion The present study examined grade-level differences in relative schoolbag load carriage among primary and lower secondary students in an urban public school in Uzbekistan. The main finding was a progressive and statistically significant decrease in relative schoolbag load across school grades, with Grade 1 pupils carrying the highest relative loads (mean %BWavg = 13.9%; mean %BWmax = 16.5%) and Grade 7 students carrying the lowest (mean %BWavg = 8.9%; mean %BWmax = 10.8%). These results are consistent with the study hypothesis and align with previous international evidence indicating that younger pupils tend to carry disproportionately heavier relative loads compared with their older counterparts [5,16,26,29]. Lifestyle The descriptive analysis of lifestyle characteristics provides additional insights into schoolbag load carriage patterns. Younger pupils were more likely to have lunch at home and to use private transportation, whereas older students more frequently used the school canteen and walked to school. These differences may reflect developmental changes in independence and daily routines across school grades. Overall, lifestyle-related school routines may indirectly influence schoolbag load carriage and should be considered when designing school-based strategies to reduce excessive loads. This potential underlying effect of lifestyle was explored on running logistic regressions to be discussed bellow. Load carriage The pattern of decreasing relative load with increasing grade is consistent with findings reported in several international studies. In New Zealand, Whittfield et al. [26] found that third-form pupils carried significantly heavier relative loads (13.2% BW) compared with sixth-form students (10.3% BW). Similarly, Barbosa et al. [ 29 ], in a cross-sectional study conducted in Portugal, reported that younger students carried significantly greater relative loads than older students, with notable differences in body-weight-normalized values. The present findings extend this evidence to a Central Asian context, suggesting that the inverse age–load relationship is not confined to Western or high-income countries but may represent a more generalizable developmental phenomenon. A plausible explanation for this pattern is that younger students, who have lower body mass, carry proportionally heavier bags relative to their body weight, even if the absolute bag weight does not differ substantially across grades. A particularly concerning finding is that the majority of Grade 1 pupils exceeded the standard recommendation of a 10% BW threshold, with 61–71% carrying loads between 15% and 20% BW on the heaviest day and a substantial proportion surpassing 20% BW. These values are notably higher than those typically reported for older students and raise questions about the appropriateness of a uniform 10% guideline applied indiscriminately across all school grades. Brackley and Stevenson [14] previously argued that a threshold of 10–15% BW is physiologically reasonable when accounting for aerobic capacity, energy expenditure, and cardiovascular responses. However, this recommendation was derived largely from studies on older children and adolescents, and the present findings suggest that even lower thresholds may be warranted for children in the first years of schooling. Previous biomechanical research has also shown that increasing backpack loads may significantly alter gait kinematics and kinetics in schoolchildren, potentially increasing musculoskeletal stress during walking [ 30 ]. In this context, the current study provides further grounds to reconsider the adequacy of uniform load guidelines and supports calls for age-sensitive or grade-specific recommendations [ 17 ]. The large effect sizes observed in the ANOVA analyses (η² = 0.483 for %BWmax; η² = 0.635 for %BWavg) highlight the magnitude of grade-level differences in relative schoolbag load. Post-hoc comparisons revealed statistically significant pairwise differences between Grade 1 and all other grades, as well as between Grade 3 and Grade 7, with large effect sizes (0.881 < d < 3.611). Notably, the comparison between Grades 3 and 5 was not statistically significant, with a small effect size (0.149 < d < 0.220), suggesting that the transition from third to fifth grade does not substantially alter relative load carriage. The comparison between Grades 5 and 7 also yielded a non-significant result (P = 0.073), although a medium effect size was observed (d = 0.649), which may reflect a meaningful practical difference despite the lack of statistical significance, a distinction worth considering in future studies with larger samples. Prospective determinants The logistic regression analyses revealed that sex and BMI did not significantly predict whether pupils carried loads exceeding 10% BW, neither on the heaviest day nor on average across the week. This contrasts with some prior evidence suggesting that sex [16,27] and BMI [ 5 ] may influence schoolbag load carriage. For example, White et al. [ 16 ] reported that boys in grades 5–12 carried heavier loads than girls, and Dockrell et al. [ 5 ] found that overweight children transported greater absolute loads than peers of normal weight. The absence of significant sex and BMI effects in the present study may reflect the relatively homogeneous sample or the specific measurement approach employed, and warrants further investigation in larger and more diverse cohorts. In contrast, lunch place emerged as a significant determinant in the average weekly load model (OR = 0.325; P = 0.007), indicating that students who eat at school are less likely to carry loads exceeding 10% BW over the week. This finding may reflect contextual factors, as students who eat at home may need to carry additional materials or food-related items or may have different commuting patterns that influence total carried load. Mode of transportation showed a borderline association (OR = 1.625; P = 0.066), which may reflect the tendency for students who walk to school to carry all necessary materials in a single trip, increasing cumulative load exposure. Regional Considerations and Recommendations The contextual setting of this study provides an important backdrop for interpreting the findings. In Uzbekistan, as in many other Central Asian countries, students are commonly required to transport multiple textbooks and educational materials daily due to the absence of locker facilities in most public schools. Furthermore, walking is the predominant mode of school transportation, particularly among older students, while the use of private transportation was more common among Grade 1 pupils. These factors may collectively contribute to the high relative loads observed, particularly in younger grades. To the best of our knowledge, this study is the first to quantify schoolbag load carriage in Uzbekistan, thereby addressing a significant gap in the regional literature. The findings are broadly consistent with evidence from other Asian countries, where excessive schoolbag loads have also been reported as a widespread concern [31,32]. From a practical standpoint, the present findings have several implications for school health policy and ergonomic practice. Given the disproportionately high relative loads observed in Grade 1 pupils, targeted interventions should be prioritized for the early primary school years. These may include the introduction of locker facilities to allow students to leave non-essential materials at school, the adoption of digital or lighter educational resources to reduce the total weight of transported items, and the implementation of teacher awareness programs regarding recommended load limits. Additionally, school administrators and curriculum planners should consider distributing heavy textbooks more evenly throughout the school week to reduce peak load exposure. Parents and students should also be educated about the risks associated with excessive schoolbag loads and trained in proper backpack adjustment and usage techniques. The significant association between lunch place and load carriage further suggests that canteen-based lunch provision may serve as a relevant school-level health promotion strategy. Limitations Several limitations should be considered when interpreting the present findings. First, the use of a convenience sampling approach from a single urban public school in Urgench limits the generalizability of the results to other school settings, regions, or types of schools in Uzbekistan. Future studies should aim to include multiple schools, rural settings, and more diverse socioeconomic contexts. Second, the unequal sample size across grades, particularly the larger Grade 5 group, may have introduced some imbalance in the statistical comparisons despite the use of bootstrapping procedures. Third, the cross-sectional design precludes causal inferences; longitudinal studies would be needed to determine whether load exposure patterns are stable or change within individual students over time. Finally, potential confounders such as the number of subjects per class, the specific school schedule, or whether students carried optional versus mandatory materials were not systematically assessed. Conclusion In conclusion, this study demonstrates that younger pupils in Uzbekistan are disproportionately exposed to excessive relative schoolbag loads compared with older students, with Grade 1 children showing the highest and most concerning levels of load carriage. The findings question the adequacy of a uniform 10% BW guideline applied across all school grades and underscore the need for age-sensitive preventive strategies. Lunch place was identified as a potentially modifiable school-related determinant of load exposure. These results contribute to a growing body of international evidence on schoolbag load carriage and provide an initial empirical foundation for evidence-based policy development in Uzbekistan and the broader Central Asian region. Declarations Acknowledgements The author would like to express sincere gratitude to the founder of Mamun University, Arslon Nurjonov , for his generous financial support, which made the publication of this article possible. The author also extends special thanks to the professors of Instituto Politécnico de Bragança for their valuable guidance, scientific support, and insightful recommendations throughout the research process. The author is deeply grateful to Ibragimov Dilmurat , the director of School No. 25 in Urgench city, for his kind support and assistance in facilitating the research process. Furthermore, the author appreciates the contribution of all participants, including children, parents, and educators, whose active involvement made this study possible. Finally, the author acknowledges all colleagues and mentors who provided constructive feedback and support, significantly improving the quality of this research. Author Contributions O.S. conceived and designed the study. O.S. and T.M.B. supervised the research and contributed to the study design. O.S., A.S., J.J., A.A. and T.S. conducted the assessments and collected the data. O.S., O.X. and G.S. performed the data analysis and interpretation. A.C.J.A. and T.M.B. contributed to the methodological framework and critically revised the manuscript. O.S. wrote the original draft of the manuscript. All authors edited the manuscript and approved the final version. O.S. is the corresponding author of this study. T.M.B. supervised the research process in the role of scientific advisor. Additional information Competing financial interests: The authors declare no competing financial interests. Funding: This research received no external funding. The article processing charge (APC) will be covered by the corresponding author. References 1. Jayaratne K, Jacobs K, Fernando D. Global healthy backpack initiatives. Work. 2012;41(Suppl 1):5553–7. 2. Rose K, Davies A, Pitt M, Ratnasinghe D, D'Argenzio L. 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BMC Res Notes. 2014;7:222. 9. Hestbaek L, Leboeuf-Yde C, Kyvik KO, Manniche C. The course of low back pain from adolescence to adulthood: eight-year follow-up of 9600 twins. Spine. 2006;31(4):468–72. 10. Brattberg G. Do pain problems in young school children persist into early adulthood? A 13-year follow-up. Eur J Pain. 2004;8(3):187–99. 11. Maniadakis N, Gray A. The economic burden of back pain in the UK. Pain. 2000;84(1):95–103. 12. Hong Y, Brueggemann GP. Changes in gait patterns in 10-year-old boys with increasing loads when walking on a treadmill. Gait Posture. 2000; 11(3):254–9. 13. Mosaad DM, Abdel-Aziem AA. Backpack carriage effect on head posture and ground reaction forces in school children. Work. 2015;52(1):203–9. 14. Brackley HM, Stevenson JM. Are children's backpack weight limits enough? A critical review of the relevant literature. Spine. 2004;29(19):2184–90. 15. Al-Hazzaa HM. Schoolbackpack - how much load do Saudi school boys carry on their shoulders? Saudi Med J. 2006;27(10):1567–71. 16. White GL, Moore MJ, Moore DL. Association of relative backpack weight with reported pain, pain sites, medical utilization, and lost school time in children and adolescents. J Sch Health. 2007;77(5):232–9. 17. Dockrell S, Simms C, Blake C. Schoolbag weight limit: can it be defined? J Sch Health. 2013;83(5):368–77. 18. Negrini S, Carabalona R, Sibilia P. Backpack as a daily load for schoolchildren. Lancet. 1999;354(9194):1974. 19. Goodgold S, Corcoran M, Gamache D, Gillis J, Guerin J, Coyle JQ. Backpack use in children. Pediatr Phys Ther. 2002;14(3):122–31. 20. Brackley HM, Stevenson JM, Selinger JC. Effect of backpack load placement on posture and spinal curvature in prepubescent children. Work. 2009;32(3): 351–60. 21. Mallakzadeh M, Javidi M, Azimi S, Monshizadeh H. Analyzing the potential benefits of using a backpack with non-flexible straps. Work. 2016;54(1):11–20. 22. Ramadan MZ, Al-Shayea AM. A modified backpack design for male school children. Int J Ind Ergon. 2013;43:462–71. 23. Mackie HW, Legg SJ, Beadle J, Hedderley D. Comparison of four different backpacks intended for school use. Appl Ergon. 2003;34(3):257–64. 24. Dahl KD, Wang H, Popp JK, Dickin DC. Load distribution and postural changes in young adults when wearing a traditional backpack versus the BackTpack. Gait Posture. 2016;45:90–6. 25. Haig AJ, Young IA, Yamakawa KS. The association between backpack weight and low back pain in children. J Back Musculoskelet Rehabil. 2006;19(1):25–33. 26. Whittfield JK, Legg SJ, Hedderley DI. The weight and use of schoolbags in New Zealand secondary schools. Ergonomics. 2001;44(9):819–24. 27. Dianat I, Javadivala Z, Asghari-Jafarabadi M, Asl Hashemi A, Haslegrave CM. The use of schoolbags and musculoskeletal symptoms among primary school children: are the recommended weight limits adequate? Ergonomics. 2013;56(1):79–89. 28. Durlak JA. How to select, calculate, and interpret effect sizes. J Pediatr Psychol. 2009;34(9):917–28. 29. Barbosa J, Marques MC, Izquierdo M, et al. Schoolbag weight carriage in Portuguese children and adolescents: a cross-sectional study comparing possible influencing factors. BMC Pediatr. 2019;19(1):157. 30. Ahmad, Habibah N. and Tiago M. Barbosa. “The effects of backpack carriage on gait kinematics and kinetics of schoolchildren.” Scientific Reports 9 (2019): n. pag. 31. Hong Y, Brueggemann GP. Changes in gait patterns in 10-year-old boys with increasing loads when walking on a treadmill. Gait Posture. 2000;11(3):254-259. 32. Ramprasad M, Alias J, Raghuveer AK. Effect of backpack weight on postural angles in preadolescent children. Indian Pediatr. 2010;47(7):575-580. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 18 May, 2026 Reviewers agreed at journal 01 May, 2026 Reviewers invited by journal 30 Mar, 2026 Editor invited by journal 27 Mar, 2026 Editor assigned by journal 24 Mar, 2026 Submission checks completed at journal 24 Mar, 2026 First submitted to journal 20 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9181546","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":614484575,"identity":"cff450d8-6a39-46bb-a4b9-d61578883843","order_by":0,"name":"Orifjon Saidmamatov","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7klEQVRIiWNgGAWjYFACxgYJBgYJfsYGBsYHQC4PH7FaJBsbGJgNQFrYiLEHqIVBsoGBgQ3EYCCoRb79cOONj3ssJJjbe49Vfs2xk2FjYH746AYeLQZnEpstZzyTkGDsOZd2W3ZbMtBhbMbGOfi0MCS2SfMckKhjnJFjdltyGzNQCw+bND4t8v0PwVokQFqKJbfVE9bCcCMRoYXx47bDhLUY3HgI9AtIS88ZY2nGbcd52JgJ+EW+P/3hjQ8H6iQM23sMP/7cVm3Pz9788DFeh8GAYQMDAzMPiMVMjHKwdUDM+INY1aNgFIyCUTCiAACr/UQAlawkGwAAAABJRU5ErkJggg==","orcid":"","institution":"Mamun University","correspondingAuthor":true,"prefix":"","firstName":"Orifjon","middleName":"","lastName":"Saidmamatov","suffix":""},{"id":614484576,"identity":"6883ea0a-1298-42b7-bc38-7f62b6498aad","order_by":1,"name":"Allabergan Sharipov","email":"","orcid":"","institution":"Mamun University","correspondingAuthor":false,"prefix":"","firstName":"Allabergan","middleName":"","lastName":"Sharipov","suffix":""},{"id":614484577,"identity":"35d563ea-25e4-4fb9-bd6e-cbda9b11cc8c","order_by":2,"name":"Jasurbek Jammatov","email":"","orcid":"","institution":"Mamun University","correspondingAuthor":false,"prefix":"","firstName":"Jasurbek","middleName":"","lastName":"Jammatov","suffix":""},{"id":614484578,"identity":"afd24f1c-2739-48d7-9bea-2f8bbb8922aa","order_by":3,"name":"Adilbek Atajanov","email":"","orcid":"","institution":"Mamun University","correspondingAuthor":false,"prefix":"","firstName":"Adilbek","middleName":"","lastName":"Atajanov","suffix":""},{"id":614484579,"identity":"d97bcc2f-66a8-4b2e-886b-feed814e5b2f","order_by":4,"name":"Taxirbek Salayev","email":"","orcid":"","institution":"Mamun University","correspondingAuthor":false,"prefix":"","firstName":"Taxirbek","middleName":"","lastName":"Salayev","suffix":""},{"id":614484580,"identity":"7c892f46-20f1-4659-90e1-bdec3f8e1557","order_by":5,"name":"Ozod Xasanov","email":"","orcid":"","institution":"Urgench State University","correspondingAuthor":false,"prefix":"","firstName":"Ozod","middleName":"","lastName":"Xasanov","suffix":""},{"id":614484581,"identity":"27309d0d-e73c-4b93-8e08-cad7c3ce2d73","order_by":6,"name":"Gayrat Shikhov","email":"","orcid":"","institution":"Mirzo Ulugbek National University of Uzbekistan","correspondingAuthor":false,"prefix":"","firstName":"Gayrat","middleName":"","lastName":"Shikhov","suffix":""},{"id":614484582,"identity":"ac0be43b-ed1b-4622-80e9-4c4a62eb6900","order_by":7,"name":"Ana Cristina Jesus Alves","email":"","orcid":"","institution":"Instituto Politécnico de Bragança","correspondingAuthor":false,"prefix":"","firstName":"Ana","middleName":"Cristina Jesus","lastName":"Alves","suffix":""},{"id":614484583,"identity":"250c8186-b340-415b-b737-92120cf96247","order_by":8,"name":"Tiago M. Barbosa","email":"","orcid":"","institution":"Instituto Politécnico de Bragança","correspondingAuthor":false,"prefix":"","firstName":"Tiago","middleName":"M.","lastName":"Barbosa","suffix":""}],"badges":[],"createdAt":"2026-03-20 19:08:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9181546/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9181546/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106401695,"identity":"e187cf4b-22f9-4247-89e5-8e1a00ff9555","added_by":"auto","created_at":"2026-04-08 09:09:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1000533,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9181546/v1/2f84c680-3f4b-446f-8598-44f93522fa86.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eSchoolbag Load and Relative Weight Among Schoolchildren in Central Asia: A Cross-sectional Study From Uzbekistan\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe transportation of heavy schoolbags by children has been largely recognized as a matter of concern among professionals involved in education, health care, and child well-being [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Backpacks, which are the most commonly used type of schoolbag, have been linked to several adverse musculoskeletal outcomes when overloaded, including alterations in spinal curvature [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], physical discomfort, and pain in the back and shoulder regions [\u003cspan additionalcitationids=\"CR6 CR7\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Importantly, musculoskeletal complaints such as back pain experienced during childhood and adolescence may persist over time and are considered predictors of back pain in adulthood [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Consequently, beyond its impact on health and quality of life, excessive schoolbag weight also represents an economic issue, as back pain constitutes a costly and widespread global health problem [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlterations in walking mechanics and postural control have been documented when children carry loads exceeding 10% of their body weight [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. However, even lower load levels may lead to adjustments in cervical alignment and changes in ground reaction forces [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Brackley et al. [14] argued that a recommended threshold of 10\u0026ndash;15% of body weight is physiologically reasonable, taking into account factors such as maximal oxygen uptake, overall energy expenditure, cardiovascular responses, and tidal volume. Although no universally agreed-upon standard has been established, restricting schoolbag weight to 10% of body weight remains the most commonly cited guideline in the literature [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Despite these recommendations, many children continue to carry loads that exceed this suggested limit [1, 15, 18, 19].\u003c/p\u003e \u003cp\u003eConsequently, various recommendations have been developed to improve backpack load distribution [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], and alternative design solutions have been introduced to reduce mechanical strain [7, 21\u0026ndash;24]. In addition, governments, professional organizations, and educational institutions worldwide have implemented initiatives aimed at mitigating the adverse health effects associated with heavy schoolbag carriage [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and at identifying effective strategies to limit children\u0026rsquo;s exposure to excessive loads [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral underlying determinants have been reported to influence schoolbag load carriage, including age [26], sex [16, 27], and body mass index (BMI) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. For example, research conducted in New Zealand demonstrated that younger pupils (third form) carried significantly heavier loads, averaging 7.0 kg (13.2% BW), compared with sixth-form primary school students, who carried 6.3 kg (10.3% BW) at approximately 11 years of age (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) [26]. Similarly, in Northern California, girls from 5th to 12th grade were found to carry heavier loads (6.2 kg; 11.3% BW) than boys (5.8 kg; 9.9% BW) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Evidence from Ireland further indicated that overweight children aged 9\u0026ndash;11 years transported greater loads (5.0 kg) compared with peers of normal weight (4.7 kg) (p\u0026thinsp;=\u0026thinsp;0.034) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In addition, findings from a cross-sectional investigation conducted in Portugal revealed that younger students (grade 5) carried significantly greater relative loads than older students (grade 9), with a substantial difference in body-weight-normalized values (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Evidence from Asian countries also indicates that excessive schoolbag load carriage is a widespread concern among schoolchildren. Studies conducted in China and India have reported that students frequently carry schoolbags exceeding recommended weight limits, with younger students being disproportionately affected [31, 32].\u003c/p\u003e \u003cp\u003eDespite growing international concern regarding excessive schoolbag loads and their potential impact on children's musculoskeletal health, evidence from Central Asia remains extremely limited. To the best of our knowledge, no studies have specifically investigated schoolbag load carriage among schoolchildren in Uzbekistan and neighboring countries.\u003c/p\u003e \u003cp\u003eThis region may present unique contextual and environmental factors influencing schoolbag load carriage. In many schools, students are required to carry multiple textbooks and educational materials daily due to the absence of locker facilities. Furthermore, active commuting, such as walking to and from school, is common, which may increase the physical burden associated with schoolbag carriage. These contextual differences highlight the need for region-specific investigations.\u003c/p\u003e \u003cp\u003eThe aim of this study was to assess schoolbag load carriage and its relative weight in relation to students\u0026rsquo; body mass across different school grades, as well as to examine the influence of selected school-related factors.\u003c/p\u003e \u003cp\u003eBased on previous international evidence [5, 16, 26, 29], it was hypothesized that younger students would carry relatively heavier schoolbag loads compared with older students, and that school-related factors would significantly influence the relative schoolbag load carried by students.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eStudy design and setting\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was designed as a cross-sectional observational investigation conducted at an urban public school in Uzbekistan. Four school grades (1, 3, 5, and 7) were selected to gather insights on the changes in schoolbag load carriage over school years.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eParticipants\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003cbr\u003e\u003c/strong\u003eA total of 108 students from four school grades participated in this study (Grade 1: n = 23, including 12 boys and 11 girls; Grade 3: n = 24, including 12 boys and 12 girls; Grade 5: n = 38, including 22 boys and 16 girls; Grade 7: n = 23, including 8 boys and 15 girls). Participants were recruited using a convenience sampling approach from a public urban school located in Urgench, Uzbekistan. All eligible students enrolled in the selected school and meeting the inclusion criteria were invited to participate in the study.\u003c/p\u003e\n\u003cp\u003eInclusion criteria were as follows: (1) enrollment in a regular education program; (2) attendance at a public urban school; (3) full-time school attendance; (4) enrollment in Grade 1, Grade 3, Grade 5, or Grade 7 at the time of data collection; and (5) absence of diagnosed musculoskeletal disorders, chronic diseases, or other medical conditions that could influence schoolbag load carriage, as confirmed by school medical records.\u003c/p\u003e\n\u003cp\u003eExclusion criteria were as follows: (1) enrollment in special education programs; (2) attendance at private or rural schools; (3) part-time school attendance; (4) enrollment in grades other than Grade 1, Grade 3, Grade 5, or Grade 7; and (5) presence of diagnosed musculoskeletal disorders, chronic diseases, or other medical conditions that could affect schoolbag load carriage, based on school medical records.\u003c/p\u003e\n\u003cp\u003eThe study protocol was reviewed and approved by the 78/2 Ethical Committee of Mamun University (approval date: 28 November 2025). All procedures were conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from parents or legal guardians prior to participation, and verbal assent was obtained from all students.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eData collection\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLifestyle\u003c/p\u003e\n\u003cp\u003eSeveral lifestyle school-related behaviors were recorded from each pupil, such as where do they have lunch (at home, at school canteen or at school brining the meal from home), the mode of transportation to school (walking, public transportation or private transportation), the features of the schoolbag (single stripe, two stripes or briefcase), Grade 1 and 3 pupils had one Physical Education lesson per week; whereas Grades 5 and 7, two lessons per week.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLoad carriage\u003c/p\u003e\n\u003cp\u003eData collection was carried out during five consecutive school days (Monday to Friday). Each student’s schoolbag was weighed once per day, resulting in repeated measurements for every participant. All measurements were performed in the morning upon arrival at school, before the beginning of classes.\u003c/p\u003e\n\u003cp\u003eIf students carried additional bags (e.g., sports bags), each bag was weighed separately, and the total carried load was calculated as the cumulative weight of all bags.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll measurements were obtained using a portable digital luggage scale (OriGlam, Handheld Luggage Weight Scale, China) with a measurement precision of 0.05 kg. Schoolbags measurements were performed under standardized conditions, individually. The scale was calibrated prior to data collection in accordance with the manufacturer’s instructions.\u003c/p\u003e\n\u003cp\u003eAnthropometrics\u003c/p\u003e\n\u003cp\u003eBody mass was measured to the nearest 0.5 kg using a digital weighing scale (Artel ART-EB-1170, Artel Electronics LLC, Uzbekistan). Body height was measured to the nearest 0.5 cm using a floor-mounted mechanical medical stadiometer (R-Ss-MSK, Russia) with a maximum measurement range of 210 cm. Prior to data collection, the instruments were checked for proper functioning and calibrated according to the manufacturer’s instructions. All measurements were performed under standardized conditions, with students wearing light clothing and no footwear.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBody mass index (BMI) was calculated as body mass divided by height squared (kg/m²). BMI classification was performed according to World Health Organization (WHO) reference standards.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSchoolbag load was expressed relative percentage of body weight (%BW). It was computed the average relative load carried over the school week (%BWavg) and the day of heaviest load (%Bwmax).\u003c/p\u003e\n\u003cp\u003eA schoolbag load exceeding 10% of the student’s body weight was deemed as excessive, in accordance with established international recommendations [14,18].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eStatistical analysis\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData is reported as mean\u0026nbsp;±\u0026nbsp;1 SD of absolute and relative frequencies. 95% confidence intervals are also stated.\u003c/p\u003e\n\u003cp\u003eOne-way analysis of variance for %BWavg and %BWmax were computed. Tukey was selected as post-hoc test. Data was bootstrapped for 1,000 successful replicates. Standardized effect sizes were calculated for both ANOVA by eta squared and for post-hoc testing by pairwise Cohen´s d. Eta squared interpretation was set as small (≤0.01), medium (0.06), or large (≥0.14). Cohen´s d was deemed as small (≤0.2), medium (0.5), or large (≥0.8). Statistical significance was set at p \u0026lt; 0.05.\u003c/p\u003e\n\u003cp\u003eThereafter, logistic regressions to learn what are the lifestyle school-related determinants (exogenous variables) that might lead pupils to carry overloads or a load within 10% of body weight (endogenous variable) were computed.\u003c/p\u003e\n\u003cp\u003eTo run an ANOVA one-way, assuming an effect size of 0.40, alpha error of 0.05, 90% power analyzing 4 school grades, the expected a priori sample size was 96 pupils (24 in each grade).\u0026nbsp;\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eLifestyle\u003c/p\u003e \u003cp\u003ePupils from Grade 1 were more likely to have lunch at home (96%), whereas older counterparts from Grade 7 prefer to have at school canteen (83%, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Conversely, pupils from Grades 3 and 5 split up between those having at home and at the canteen. Hence, over time there is shift in the place where pupils have their lunch. As far as mode of transportation is concerned, most were choosing to walk. That said, a good portion of Grade 1 students (43%) were fetched on private transportation (i.e. family car). All students were carrying schoolbags with two stripes.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSample characteristics and lifestyle.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"13\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eLunch place\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c10\" namest=\"c8\"\u003e \u003cp\u003eMode of transportation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e \u003cp\u003eType of schoolbag\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBoys\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGirls\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003etotal\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAt Home\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAt canteen\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eBrought from home\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eWalking\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003ePublic transportation\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003ePrivate transportation n(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eOne stripe\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eTwo stripes\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c13\"\u003e \u003cp\u003eBriefcase\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e22(96%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1(4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e12(52%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1(4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e10(43%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e23(100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10(42%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14(58%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e20(83%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e4(17%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e24(100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade 5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e17(45%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e21(55%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e35(92%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e3(8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e38(100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade 7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4(17%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e19(83%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e17(74%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e6(26%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e23(100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eLoad carriage\u003c/p\u003e \u003cp\u003eReferring to the day that pupils are carrying the heaviest load (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), regardless of the BMI, 61% to 71% of Grade 1 pupils were carrying loads between 15% and 20% of the body weight. Most of Grade 3 and Grade 5 pupils were carrying 10 to 15% of the body weight (Grade 3: 56 to 88%; Grade 5: 89% to 94%). Interestingly, Grade 7 students were carrying 10\u0026ndash;15% (38% to 57%) or even less (23% to 39%). As such, one can note that the percentage of body weight carried decreased over school years.\u003c/p\u003e \u003cp\u003eThat said, a close inspection to the average of all school days of the week (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), 14% to 58% of Grade 1 pupils were carrying 10\u0026ndash;15% of body weight or, 18% to 31% of 15\u0026ndash;20% of body weight. In the other three school grades, pupils were more prone to carry mostly less than 10% of their body weight (Grade 3: 56% to 76%; Grade 5: 65% to 79%; Grade 7: 74% to 80%).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLoad carriage normalized to body weight by all subjects and just pupils with normal body mass index.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eLoad\u003c/p\u003e \u003cp\u003e[in BW]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eDay of heaviest load\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eAll Days\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAll pupils\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNormal BMI\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAll pupils\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNormal BMI\u003c/p\u003e \u003cp\u003en(%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eGrade 1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8(7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e53(62%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;10% \u0026amp; \u0026le;15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6(26%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1(6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e67(58%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12(14%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;15% \u0026amp; \u0026le;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14(61%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12(71%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e36(31%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15(18%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3(3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4(24%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4(3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5(6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eGrade 3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1(4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1(6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e67(56%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e68(76%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;10% \u0026amp; \u0026le;15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21(88%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10(56%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50(42%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15(17%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;15% \u0026amp; \u0026le;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1(4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1(6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2(2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1(1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1(4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6(33%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1(1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6(7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eGrade 5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e150(65%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e63(79%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;10% \u0026amp; \u0026le;15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34(89%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15(94%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e76(33%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e16(20%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;15% \u0026amp; \u0026le;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4(11%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4(2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1(6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1(1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eGrade 7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9(39%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3(23%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e85(74%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e52(80%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;10% \u0026amp; \u0026le;15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13(57%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5(38%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e29(25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8(12%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;15% \u0026amp; \u0026le;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1(4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1(8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1(1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1(2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4(31%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0(0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4(6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eEffect of lifestyle school-determinants in load carriage School Grade. Analysis of variance of the heaviest load day [F(3,104)\u0026thinsp;=\u0026thinsp;32.37, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001, η\u0026sup2;=0.483] and the average load of all days [F(3,104)\u0026thinsp;=\u0026thinsp;60.30, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001, η\u0026sup2;=0.635] among school grades (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) yielded significant variations with large effect sizes.\u003c/p\u003e \u003cp\u003eFollow-up post-hoc test (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) revealed that there were pairwise significant differences (0.001\u0026thinsp;\u0026lt;\u0026thinsp;P\u0026thinsp;\u0026lt;\u0026thinsp;0.2) with strong effect sizes between most school grades (0.881\u0026thinsp;\u0026lt;\u0026thinsp;d\u0026thinsp;\u0026lt;\u0026thinsp;3.611). All in all, the mean percentage of body weight carried decreased over school years. Only exception is comparing Grade 3 to Grade 5, where the pairwise comparison was not significant, with small effect sizes (0.833\u0026thinsp;\u0026lt;\u0026thinsp;P\u0026thinsp;\u0026lt;\u0026thinsp;0.940; 0.149\u0026thinsp;\u0026lt;\u0026thinsp;d\u0026thinsp;\u0026lt;\u0026thinsp;0.220). Interestingly, comparing Grade 5 to Grade 7 the pairwise was not significant (P\u0026thinsp;=\u0026thinsp;0.073) but the effect size was medium (d\u0026thinsp;=\u0026thinsp;0.649).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAnalysis of variance of heaviest load day and the average load of all days among school grades.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eη\u0026sup2;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e95CI η\u0026sup2; Lower\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e95CI η\u0026sup2; Upper\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e \u003cp\u003eDay of Heaviest load\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.165\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e3(104)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e32.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e0.483\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e0.341\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e0.586\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.129\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.024\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.126\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.108\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.016\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e \u003cp\u003eAverage load of all days\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.139\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.021\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e3(104)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e60.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e0.635\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e0.522\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e0.712\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.098\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.089\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.014\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePost-hoc test of the analysis of variance of heaviest load day and the average load of all days among school grades.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean difference of bootstrapped medians\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e95 CI bootstrap\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ebias\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eCohen's d\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003e95 CI Cohen\u0026acute;s d\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLower\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUpper\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eLower\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eUpper\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"12\" nameend=\"c12\" namest=\"c1\"\u003e \u003cp\u003eDay of heaviest load\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG1 v G3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.036\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.022\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.048\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-2.092\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e6.110\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.783\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.931\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e2.635\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG1 v G5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.039\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.029\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.052\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1.541\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e7.313\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.932\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1.135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e2.729\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG1 v G7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.056\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.047\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.071\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-3.505\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.539\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2.813\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1.862\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e3.764\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG3 v G5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.017\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e5.509\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.572\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.149\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.553\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.851\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e.940\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG3 v G7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.021\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.035\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1.412\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e3.530\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.030\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.222\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.838\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG5 v G7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.027\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1.963\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e3.334\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.881\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.151\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.610\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e.006\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"12\" nameend=\"c12\" namest=\"c1\"\u003e \u003cp\u003eAverage load of all days\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG1 v G3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.038\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.030\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.049\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.686\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.394\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2.741\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1.804\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e3.678\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG1 v G5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.034\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.052\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-1.932\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e11.209\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2.961\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e2.061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e3.861\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG1 v G7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.050\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.042\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.331\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;7\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e12.244\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e3.611\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e2.570\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e4.651\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026nbsp;.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG3 v G5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-5.618\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.844\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.220\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.482\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.923\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e.833\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG3 v G7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.019\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-3.653\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2.980\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.869\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.068\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.671\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e.019\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG5 v G7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.965\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e2.458\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.649\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-0.071\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1.370\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e.073\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eProspective determinants\u003c/p\u003e \u003cp\u003eLogistic regression showed a non-significant relationship (R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003eNagelkerke\u003c/sub\u003e=0.065; P\u0026thinsp;=\u0026thinsp;0.299). Hence unable to predict the reasons to carry loads greater or less than 10% of body weight on the day of heaviest load (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). None of the exogenous variables selected (sex, BMI, lunch place, mode of transportation) showed significant relationship with the fact of pupils carrying overloads or a load up to 10% of body weight.\u003c/p\u003e \u003cp\u003eHowever, there was a significant relationship (R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003eNagelkerke\u003c/sub\u003e =0.154; P\u0026thinsp;=\u0026thinsp;0.01) and ability to predict correctly 62.96% of the observed cases of for the average of all days. The final model retained the lunch place (OR\u0026thinsp;=\u0026thinsp;0.325; P\u0026thinsp;=\u0026thinsp;0.007) and up to some extent the mode of transportation as determinants (OR\u0026thinsp;=\u0026thinsp;1.625; P\u0026thinsp;=\u0026thinsp;0.066). Sex and BMI did not play a significant role in carrying overload or a load up to 10% of BW.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLogistic regression models predicting the determinant lifestyle school-related factors determining if pupils carry overloads or a load within 10% of body weight.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e \u003cp\u003eWald Test\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003e95% Confidence interval \u003c/p\u003e \u003cp\u003e(odds ratio scale)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEstimate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStandard Error\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOdds Ratio\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ez\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eWald Statistic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eLower bound\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUpper bound\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"10\" nameend=\"c10\" namest=\"c1\"\u003e \u003cp\u003eDay of heaviest load\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntercept\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.755\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.193\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.128\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.633\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.401\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.527\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.205\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e22.044\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.193\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.532\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.825\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.362\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.131\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.717\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.291\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e2.339\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.353\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.703\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.881\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.777\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.378\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.321\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1.539\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLunch Place\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1.891\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.605\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.151\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-3.123\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9.756\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.494\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMode of transportation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.668\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.285\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.950\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.342\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.483\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.019\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e3.409\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"10\" nameend=\"c10\" namest=\"c1\"\u003e \u003cp\u003eAverage load of all days\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntercept\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.420\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.171\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.242\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.066\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.269\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.039\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.132\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e111.618\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.286\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.461\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.751\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.621\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.386\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.534\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.304\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1.853\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.167\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.347\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.182\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.482\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.232\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.630\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.599\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e2.332\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLunch Place\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.820\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.476\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.440\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-1.724\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.972\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.085\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.173\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1.119\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMode of transportation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.224\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.312\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.251\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.717\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.514\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e.474\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.678\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e2.307\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe present study examined grade-level differences in relative schoolbag load carriage among primary and lower secondary students in an urban public school in Uzbekistan. The main finding was a progressive and statistically significant decrease in relative schoolbag load across school grades, with Grade 1 pupils carrying the highest relative loads (mean %BWavg\u0026thinsp;=\u0026thinsp;13.9%; mean %BWmax\u0026thinsp;=\u0026thinsp;16.5%) and Grade 7 students carrying the lowest (mean %BWavg\u0026thinsp;=\u0026thinsp;8.9%; mean %BWmax\u0026thinsp;=\u0026thinsp;10.8%). These results are consistent with the study hypothesis and align with previous international evidence indicating that younger pupils tend to carry disproportionately heavier relative loads compared with their older counterparts [5,16,26,29].\u003c/p\u003e \u003cp\u003eLifestyle\u003c/p\u003e \u003cp\u003eThe descriptive analysis of lifestyle characteristics provides additional insights into schoolbag load carriage patterns. Younger pupils were more likely to have lunch at home and to use private transportation, whereas older students more frequently used the school canteen and walked to school. These differences may reflect developmental changes in independence and daily routines across school grades. Overall, lifestyle-related school routines may indirectly influence schoolbag load carriage and should be considered when designing school-based strategies to reduce excessive loads. This potential underlying effect of lifestyle was explored on running logistic regressions to be discussed bellow.\u003c/p\u003e \u003cp\u003eLoad carriage\u003c/p\u003e \u003cp\u003eThe pattern of decreasing relative load with increasing grade is consistent with findings reported in several international studies. In New Zealand, Whittfield et al. [26] found that third-form pupils carried significantly heavier relative loads (13.2% BW) compared with sixth-form students (10.3% BW). Similarly, Barbosa et al. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], in a cross-sectional study conducted in Portugal, reported that younger students carried significantly greater relative loads than older students, with notable differences in body-weight-normalized values. The present findings extend this evidence to a Central Asian context, suggesting that the inverse age\u0026ndash;load relationship is not confined to Western or high-income countries but may represent a more generalizable developmental phenomenon. A plausible explanation for this pattern is that younger students, who have lower body mass, carry proportionally heavier bags relative to their body weight, even if the absolute bag weight does not differ substantially across grades.\u003c/p\u003e \u003cp\u003eA particularly concerning finding is that the majority of Grade 1 pupils exceeded the standard recommendation of a 10% BW threshold, with 61\u0026ndash;71% carrying loads between 15% and 20% BW on the heaviest day and a substantial proportion surpassing 20% BW. These values are notably higher than those typically reported for older students and raise questions about the appropriateness of a uniform 10% guideline applied indiscriminately across all school grades.\u003c/p\u003e \u003cp\u003eBrackley and Stevenson [14] previously argued that a threshold of 10\u0026ndash;15% BW is physiologically reasonable when accounting for aerobic capacity, energy expenditure, and cardiovascular responses. However, this recommendation was derived largely from studies on older children and adolescents, and the present findings suggest that even lower thresholds may be warranted for children in the first years of schooling. Previous biomechanical research has also shown that increasing backpack loads may significantly alter gait kinematics and kinetics in schoolchildren, potentially increasing musculoskeletal stress during walking [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. In this context, the current study provides further grounds to reconsider the adequacy of uniform load guidelines and supports calls for age-sensitive or grade-specific recommendations [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe large effect sizes observed in the ANOVA analyses (η\u0026sup2; = 0.483 for %BWmax; η\u0026sup2; = 0.635 for %BWavg) highlight the magnitude of grade-level differences in relative schoolbag load. Post-hoc comparisons revealed statistically significant pairwise differences between Grade 1 and all other grades, as well as between Grade 3 and Grade 7, with large effect sizes (0.881\u0026thinsp;\u0026lt;\u0026thinsp;d\u0026thinsp;\u0026lt;\u0026thinsp;3.611). Notably, the comparison between Grades 3 and 5 was not statistically significant, with a small effect size (0.149\u0026thinsp;\u0026lt;\u0026thinsp;d\u0026thinsp;\u0026lt;\u0026thinsp;0.220), suggesting that the transition from third to fifth grade does not substantially alter relative load carriage. The comparison between Grades 5 and 7 also yielded a non-significant result (P\u0026thinsp;=\u0026thinsp;0.073), although a medium effect size was observed (d\u0026thinsp;=\u0026thinsp;0.649), which may reflect a meaningful practical difference despite the lack of statistical significance, a distinction worth considering in future studies with larger samples.\u003c/p\u003e \u003cp\u003eProspective determinants\u003c/p\u003e \u003cp\u003eThe logistic regression analyses revealed that sex and BMI did not significantly predict whether pupils carried loads exceeding 10% BW, neither on the heaviest day nor on average across the week. This contrasts with some prior evidence suggesting that sex [16,27] and BMI [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] may influence schoolbag load carriage. For example, White et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] reported that boys in grades 5\u0026ndash;12 carried heavier loads than girls, and Dockrell et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] found that overweight children transported greater absolute loads than peers of normal weight. The absence of significant sex and BMI effects in the present study may reflect the relatively homogeneous sample or the specific measurement approach employed, and warrants further investigation in larger and more diverse cohorts.\u003c/p\u003e \u003cp\u003eIn contrast, lunch place emerged as a significant determinant in the average weekly load model (OR\u0026thinsp;=\u0026thinsp;0.325; P\u0026thinsp;=\u0026thinsp;0.007), indicating that students who eat at school are less likely to carry loads exceeding 10% BW over the week. This finding may reflect contextual factors, as students who eat at home may need to carry additional materials or food-related items or may have different commuting patterns that influence total carried load. Mode of transportation showed a borderline association (OR\u0026thinsp;=\u0026thinsp;1.625; P\u0026thinsp;=\u0026thinsp;0.066), which may reflect the tendency for students who walk to school to carry all necessary materials in a single trip, increasing cumulative load exposure.\u003c/p\u003e \u003cp\u003eRegional Considerations and Recommendations\u003c/p\u003e \u003cp\u003eThe contextual setting of this study provides an important backdrop for interpreting the findings. In Uzbekistan, as in many other Central Asian countries, students are commonly required to transport multiple textbooks and educational materials daily due to the absence of locker facilities in most public schools. Furthermore, walking is the predominant mode of school transportation, particularly among older students, while the use of private transportation was more common among Grade 1 pupils. These factors may collectively contribute to the high relative loads observed, particularly in younger grades.\u003c/p\u003e \u003cp\u003eTo the best of our knowledge, this study is the first to quantify schoolbag load carriage in Uzbekistan, thereby addressing a significant gap in the regional literature. The findings are broadly consistent with evidence from other Asian countries, where excessive schoolbag loads have also been reported as a widespread concern [31,32].\u003c/p\u003e \u003cp\u003eFrom a practical standpoint, the present findings have several implications for school health policy and ergonomic practice. Given the disproportionately high relative loads observed in Grade 1 pupils, targeted interventions should be prioritized for the early primary school years. These may include the introduction of locker facilities to allow students to leave non-essential materials at school, the adoption of digital or lighter educational resources to reduce the total weight of transported items, and the implementation of teacher awareness programs regarding recommended load limits.\u003c/p\u003e \u003cp\u003eAdditionally, school administrators and curriculum planners should consider distributing heavy textbooks more evenly throughout the school week to reduce peak load exposure. Parents and students should also be educated about the risks associated with excessive schoolbag loads and trained in proper backpack adjustment and usage techniques. The significant association between lunch place and load carriage further suggests that canteen-based lunch provision may serve as a relevant school-level health promotion strategy.\u003c/p\u003e \u003cp\u003eLimitations\u003c/p\u003e \u003cp\u003eSeveral limitations should be considered when interpreting the present findings. First, the use of a convenience sampling approach from a single urban public school in Urgench limits the generalizability of the results to other school settings, regions, or types of schools in Uzbekistan. Future studies should aim to include multiple schools, rural settings, and more diverse socioeconomic contexts.\u003c/p\u003e \u003cp\u003eSecond, the unequal sample size across grades, particularly the larger Grade 5 group, may have introduced some imbalance in the statistical comparisons despite the use of bootstrapping procedures. Third, the cross-sectional design precludes causal inferences; longitudinal studies would be needed to determine whether load exposure patterns are stable or change within individual students over time. Finally, potential confounders such as the number of subjects per class, the specific school schedule, or whether students carried optional versus mandatory materials were not systematically assessed.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, this study demonstrates that younger pupils in Uzbekistan are disproportionately exposed to excessive relative schoolbag loads compared with older students, with Grade 1 children showing the highest and most concerning levels of load carriage. The findings question the adequacy of a uniform 10% BW guideline applied across all school grades and underscore the need for age-sensitive preventive strategies. Lunch place was identified as a potentially modifiable school-related determinant of load exposure. These results contribute to a growing body of international evidence on schoolbag load carriage and provide an initial empirical foundation for evidence-based policy development in Uzbekistan and the broader Central Asian region.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe author would like to express sincere gratitude to the founder of Mamun University, \u003cstrong\u003eArslon Nurjonov\u003c/strong\u003e, for his generous financial support, which made the publication of this article possible.\u003c/p\u003e\n\u003cp\u003eThe author also extends special thanks to the professors of Instituto Politécnico de Bragança for their valuable guidance, scientific support, and insightful recommendations throughout the research process.\u003c/p\u003e\n\u003cp\u003eThe author is deeply grateful to \u003cstrong\u003eIbragimov Dilmurat\u003c/strong\u003e, the director of School No. 25 in Urgench city, for his kind support and assistance in facilitating the research process.\u003c/p\u003e\n\u003cp\u003eFurthermore, the author appreciates the contribution of all participants, including children, parents, and educators, whose active involvement made this study possible.\u003c/p\u003e\n\u003cp\u003eFinally, the author acknowledges all colleagues and mentors who provided constructive feedback and support, significantly improving the quality of this research.\u003cbr\u003e\u0026nbsp;\u003cbr\u003e\u0026nbsp;\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eO.S. conceived and designed the study. O.S. and T.M.B. supervised the research and contributed to the study design. O.S., A.S., J.J., A.A. and T.S. conducted the assessments and collected the data. O.S., O.X. and G.S. performed the data analysis and interpretation. A.C.J.A. and T.M.B. contributed to the methodological framework and critically revised the manuscript. O.S. wrote the original draft of the manuscript. All authors edited the manuscript and approved the final version.\u003c/p\u003e\n\u003cp\u003eO.S. is the corresponding author of this study. T.M.B. supervised the research process in the role of scientific advisor.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAdditional information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting financial interests:\u003c/strong\u003e The authors declare no competing financial interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e This research received no external funding. The article processing charge (APC) will be covered by the corresponding author.\u003cbr\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003e1. Jayaratne K, Jacobs K, Fernando D. Global healthy backpack initiatives. Work. 2012;41(Suppl 1):5553\u0026ndash;7.\u003c/p\u003e\n\u003cp\u003e2. Rose K, Davies A, Pitt M, Ratnasinghe D, D\u0026apos;Argenzio L. Backpack palsy: a rare complication of backpack use in children and young adults - a new case report. Eu J Paediatr Neurol. 2016;20(5):750\u0026ndash;3.\u003c/p\u003e\n\u003cp\u003e3. Chow DH, Kwok ML, Au-Yang AC, et al. The effect of backpack load on the gait of normal adolescent girls. Ergonomics. 2005;48(6):642\u0026ndash;56.\u003c/p\u003e\n\u003cp\u003e4. Lai JP, Jones AY. The effect of shoulder-girdle loading by a school bag on lung volumes in Chinese primary school children. Early Hum Dev. 2001; 62(1):79\u0026ndash;86.\u003c/p\u003e\n\u003cp\u003e5. Dockrell S, Simms C, Blake C. 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Changes in gait patterns in 10-year-old boys with increasing loads when walking on a treadmill. Gait Posture. 2000;11(3):254-259.\u003c/p\u003e\n\u003cp\u003e32. Ramprasad M, Alias J, Raghuveer AK. Effect of backpack weight on postural angles in preadolescent children. Indian Pediatr. 2010;47(7):575-580.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"schoolbag load, backpack weight, children, developmental differences, musculoskeletal health, Uzbekistan","lastPublishedDoi":"10.21203/rs.3.rs-9181546/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9181546/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eExcessive 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 largely recommended, evidence from Central Asian countries remains limited. This study aimed to examine grade-level differences in relative schoolbag load carriage and to assess selected school-related lifestyle factors influencing load exposure among primary and lower secondary students in Uzbekistan. Methods: A cross-sectional observational study was conducted among 108 students from four grade levels (Grades 1, 3, 5, and 7) in an urban public school. Schoolbags were weighed daily across five consecutive school days of the week. Relative load was expressed as percentage of body weight (%BW). The average weekly load (%BWavg) and the heaviest-day load (%BWmax) were calculated. One-way ANOVA with bootstrapping (1,000 replicates) was used to analyze variations among school grades.\u003c/p\u003e\n\u003cp\u003eResults: Significant grade-level variations with large effects were observed in both %BWmax (p\u0026lt;0.001, η²=0.483) and %BWavg (p\u0026lt;0.001, η²=0.635). Relative load decreased progressively over school grades. Grade 1 pupils carried the highest relative loads (mean %BWavg = 13.9%), with a substantial proportion exceeding 15–20% BW on the heaviest day. Conversely, older students were more likely to remain below the 10% threshold on weekly average measures. No significant variations were found based on sex. Conclusions: Younger pupils are disproportionately exposed to excessive relative schoolbag loads. These findings question the adequacy of a uniform 10% BW guideline across grades and highlight the need for age-sensitive preventive strategies in school settings.\u003c/p\u003e","manuscriptTitle":"Schoolbag Load and Relative Weight Among Schoolchildren in Central Asia: A Cross-sectional Study From Uzbekistan","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-31 15:30:04","doi":"10.21203/rs.3.rs-9181546/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"24915533691499888644923785765762250472","date":"2026-05-18T08:52:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"46391543847527044422449203268885872195","date":"2026-05-01T16:07:56+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-30T08:08:28+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-27T11:18:07+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-24T06:55:17+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-24T06:54:52+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-03-20T19:02:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a1b776b2-ad7e-4e29-9270-61d86bbc4a4a","owner":[],"postedDate":"March 31st, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"24915533691499888644923785765762250472","date":"2026-05-18T08:52:44+00:00","index":23,"fulltext":""},{"type":"reviewerAgreed","content":"46391543847527044422449203268885872195","date":"2026-05-01T16:07:56+00:00","index":21,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":65480716,"name":"Health sciences/Health care"},{"id":65480717,"name":"Health sciences/Medical research"},{"id":65480718,"name":"Health sciences/Risk factors"}],"tags":[],"updatedAt":"2026-03-31T15:30:04+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-31 15:30:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9181546","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9181546","identity":"rs-9181546","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}