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Table 4 Mean, standard deviation and p-value of backpack and total load expressing in kilograms and normalizing for body mass by gender, physical education participation, BMI, afternoon with classes and lunch spot

From: Schoolbag weight carriage in Portuguese children and adolescents: a cross-sectional study comparing possible influencing factors

  Backpack Total load
5th grade 9th grade 5th grade 9th grade
load (kg) load·BW−1 load (kg) load·BW−1 load (kg) load·BW−1 load (kg) load·BW−1
Sex
 M 4.87 (1.42) 0.129 (0.046) 3.75 (1.25) 0.064 (0.022) 5.27 (1.57) 0.139 (0.050) 4.08 (1.47) 0.072 (0.027)
 F 5.13 (1.42) 0.131 (0.042) 4.29 (1.13) 0.087 (0.026) 5.56 (1.48) 0.141 (0.046) 4.64 (1.39) 0.095 (0.032)
p 0.064 0.546 < 0.001 < 0.001 0.040 0.513 < 0.001 < 0.001
BMI
 Normal 5.05 (1.28)   4.09 (1.14)   5.45 (1.37)   4.46 (1.43)  
 Overw. 5.19 (1.50)   4.48 (1.25)   5.66 (1.67)   4.86 (1.43)  
p 0.730   0.027   0.467   0.044  
Physical Education day
 Yes 4.63 (1.12) 0.123 (0.037) 4.00 (1.25) 0.080 (0.026) 5.64 (1.42) 0.148 (0.047) 4.83 (1.64) 0.097 (0.035)
 No 5.20 (1.55) 0.134 (0.048) 4.10 (1.19) 0.076 (0.028) 5.26 (1.59) 0.136 (0.049) 4.14 (1.23) 0.077 (0.028)
p 0.003 0.057 0.651 0.163 0.018 0.061 < 0.001 < 0.001
Afternoon with classes
 Yes 5.39 (1.49) 0.132 (0.046) 4.13 (1.24) 0.080 (0.028) 5.87 (1.50) 0.153 (0.049) 4.56 (1.49) 0.089 (0.034)
 No 4.33 (1.02) 0.114 (0.036) 3.80 (1.07) 0.069 (0.021) 4.64 (1.26) 0.120 (0.040) 3.82 (1.07) 0.069 (0.021)
p < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001
Lunch
 Home 4.31 (1.03) 0.112 (0.035) 3.60 (1.04) 0.065 (0.019) 4.63 (1.23) 0.120 (0.040) 3.70 (1.04) 0.068 (0.020)
 School 5.25 (1.48) 0.137 (0.046) 4.38 (1.22) 0.084 (0.028) 5.69 (1.55) 0.149 (0.050) 4.90 (1.48) 0.094 (0.034)
p < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001