Table 3 Anterior cruciate ligament injury by sex and physical activity category
ACL injury, n (%)Hazard ratio for injury
PresentAbsent (%)UnadjustedAdjusted*
MaleFemaleMaleFemaleMaleFemaleMaleFemale
Frequency of participation in sports clubs
    ⩾4–5 times/week60 (2.0)22 (1.6)2890 (98.0)1381 (98.4)4.5 (3.2 to 6.5)11.7 (6.6 to 20.7)4.0 (2.7 to 6.1)8.5 (4.3 to 16.4)
    ⩽2 to 3 times/week74 (1.0)23 (0.3)7048 (99.0)7287 (99.7)2.1 (1.5 to 3.0)2.1 (1.2 to 3.7)2.0 (1.4 to 2.9)2.0 (1.1 to 8.6)
    Never56 (0.5)26 (0.2)10672 (99.5)15860 (99.8)1111
Frequency of other physical exercise
    ⩾4 to 5 times/week51 (1.0)22 (0.4)5140 (99.0)5168 (99.6)2.0 (0.7 to 5.4)N/A1.9 (0.6 to 5.7)N/A
    ⩽2 to 3 times/week137 (0.9)48 (0.3)14,752 (99.1)18845 (99.7)1.9 (0.6 to 4.6)1.8 (0.6 to 5.7)
    Never4 (0.4)0 (0)928 (99.6)756 (100)11
  • N/A, not applicable.

  • *Adjusted for father’s or other guardian’s occupation, family composition, urbanisation level of residence, perceived health status, chronic disease, number of stress symptoms weekly, overweight, smoking, drinking style and timing of puberty.