Table 3 Results from intention-to-treat analyses for psychosocial outcomes (questionnaire derived). All values Mean (SD) unless otherwise specified

Self-perceptions Physical self-worth

2.67 (0.66)

2.74 (0.64)

2.52 (0.59)

2.56 (0.63)

0.03 (-0.05, 0.11)

<0.0001

Sports competency

2.57 (0.63)

2.62 (0.60)

2.49 (0.56)

2.50 (0.61)

0.05 (-0.02, 0.12)

<0.0001

Physical conditioning

2.67 (0.62)

2.73 (0.60)

2.56 (0.58)

2.56 (0.60)

0.06 (-0.04, 0.16)

0.1077

Body attractiveness

2.34 (0.66)

2.40 (0.66)

2.23 (0.62)

2.30 (0.67)

0.06 (-0.04, 0.16)

<0.0001

Physical strength

2.52 (0.57)

2.56 (0.54)

2.46 (0.52)

2.47 (0.56)

-0.02 (-0.11, 0.07)

<0.0001

Perceived importance of physical activity

2.80 (0.53)

2.80 (0.50)

2.73 (0.48)

2.75 (0.49)

-0.01 (-0.09, 0.06)

<0.0001

Physical activity self- efficacy

3.72 (0.55)

3.73 (0.59)

3.58 (0.62)

3.49 (0.67)

0.09 (0.003, 0.18)

<0.0001

Enjoyment of physical activity

4.25 (0.64)

4.23 (0.64)

4.02 (0.75)

4.00 (0.79)

0.01 (-0.10, 0.13)

<0.0001

Enjoyment of school sport

4.01 (0.75)

3.91 (0.76)

3.66 (0.85)

3.57 (0.87)

0.01 (-0.18, 0.20)

<0.0001

Social support for physical activity

3.14 (0.72)

3.01 (0.74)

2.88 (0.75)

2.90 (0.77)

-0.16 (-0.31, -0.01)

0.0001

Social support during school sport

3.97 (0.73)

3.94 (0.70)

3.72 (0.81)

3.77 (0.79)

-0.04 (-0.23, 0.15)

0.0001

Identification of strategies to increase physical activity

3.62 (0.71)

3.56 (0.75)

3.38 (0.79)

3.36 (0.80)

-0.04 (-0.14, 0.07)

<0.0001

Perceptions of school activity environment

3.75 (0.62)

3.70 (0.61)

3.61 (0.65)

3.54 (0.66)

0.01 (-0.12. 0.13)

<0.0001