[1] Univ Calgary, Fac Kinesiol, Sport Injury Prevent Res Ctr, Calgary, AB, Canada
[2] Univ Calgary, OBrien Inst Publ Hlth, Calgary, AB, Canada
[3] Univ Calgary, Hotchkiss Brain Inst, Calgary, AB, Canada
[4] Univ Calgary, Sport Med Ctr, Fac Kinesiol, Calgary, AB, Canada
[5] Univ Calgary, Fac Kinesiol, Dinos Athlet, Calgary, AB, Canada
[6] Saracens Rugby Football Union, London, England
[7] Rugby Alberta, Calgary, AB, Canada
[8] Calgary Rugby Union, Calgary, AB, Canada
[9] Calgary Canadian Irish Athlet Assoc, Calgary, AB, Canada
[10] Univ Calgary, Cumming Sch Med, Dept Family Med, Calgary, AB, Canada
[11] Univ Witwatersrand, Fac Hlth Sci, Sch Clin Med, Wits Sport & Hlth WiSH, Johannesburg, South Africa
[12] Univ Calgary, Alberta Childrens Hosp Res Inst, Calgary, AB, Canada
[13] Univ Calgary, Cumming Sch Med, Dept Community Hlth Sci, Calgary, AB, Canada
[14] Univ Calgary, Cumming Sch Med, Dept Pediat, Calgary, AB, Canada