Returning to knee-strenuous sport before nine months after anterior cruciate ligament reconstruction (ACLR) is associated with a 6.7 times greater risk of ACL reinjury, while no association is present for muscle function symmetry and quadriceps strength. It is therefore recommended that young athletes delay their return to knee-strenuous sport until at least 9 months after ACLR. These are the findings of a Swedish research group that investigated the association between time to return to sports after ACL reconstruction and reinjury, muscle function and strength in young athletes.