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Table 2 Between group mean differences in students’ change in physical activity levels during school hours

From: The impact of school uniforms on primary school student’s physical activity at school: outcomes of a cluster randomized controlled trial

  1. Intervention 2. Control Group x Intervention Day
Differential effect
Outcome Intervention day mean (SD) Usual day mean (SD) Comparison day mean (SD) Usual day mean (SD) Estimatea p-value
Moderate-vigorous physical activity (MVPA)
Girls 36.87 (SD = 11.49) 36.24 (SD = 12.19) 35.56 (SD = 11.81) 35.57 (SD = 12.00) 0.76 [−0.47; 1.99] 0.22
Boys 40.99 (SD = 12.55) 39.76 (SD = 12.11) 40.52 (SD = 12.65) 40.38 (SD = 13.13) 0.64 [−0.65; 1.92] 0.32
All students 38.88 (SD = 12.19) 37.94 (SD = 12.27) 37.94 (SD = 12.53) 37.83 (SD = 12.77) 0.71 [−0.18; 1.60] 0.11
Counts per minute (cpm)
Girls 2572.00 (SD = 475.56) 2530.32 (SD = 516.98) 2500.05 (SD = 477.19) 2495.40 (SD = 491.03) 36.99 [−13.88; 87.86] 0.15
Boys 2820.61 (SD = 522.13) 2764.54 (SD = 516.01) 2783.29 (SD = 524.40) 2759.39 (SD = 537.64) 35.04 [−18.34; 88.41] 0.19
All students 2693.38 (SD = 513.86) 2643.55 (SD = 529.51) 2634.83 (SD = 521.72) 2619.25 (SD = 530.37) 36.41 [−0.42; 73.23] 0.053
Light physical activity
Girls 115.00 (SD = 17.92) 111.82 (SD = 19.73) 113.18 (SD = 20.65) 111.77 (SD = 18.91) 1.47 [−0.06; 3.00] 0.059
Boys 118.69 (SD = 18.81) 115.06 (SD = 19.26) 116.47 (SD = 20.66) 114.81 (SD = 19.11) 0.58 [−1.02; 2.19] 0.47
All students 116.80 (SD = 18.45) 113.39 (SD = 19.57) 114.72 (SD = 20.70) 113.18 (SD = 19.05) 1.06 [−0.05; 2.17] 0.06
Sedentary activity
Girls 201.31 (SD = 25.62) 204.18 (SD = 28.33) 203.87 (SD = 26.80) 204.01 (SD = 27.08) −2.23 [−4.49; 0.02] 0.052
Boys 193.16 (SD = 25.60) 195.39 (SD = 27.21) 195.02 (SD = 26.65) 198.35 (SD = 26.15) −1.22 [−3.58; 1.15] 0.31
All students 197.33 (SD = 25.92) 199.93 (SD = 28.13) 199.68 (SD = 27.08) 201.34 (SD = 26.81) −1.77 [−3.40; −0.14] 0.035*
  1. acontrolling for students socio-economic, school type, geographic location, wear time and sex