Eccentric Knee Flexor Strength and Risk of Hamstring Injuries in Rugby Union

Abstract

Previous HSIs and between-limb imbalance in eccentric knee flexor strength were associated with an increased risk of future HSIs in rugby union. These results support the rationale for reducing imbalance, particularly in players who have suffered a prior HSI, to mitigate the risk of future injuries.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION & THE HAMSTRINGS Implications for injury prevention & rehabilitation

“…Previous work has shown that deficits in eccentric knee flexor strength during the performance of the Nordic hamstring exercise are associated with a 4.3 to 4.4-fold increased risk of future hamstring injury in elite Australian rules footballers (Opar et al, 2015a) and professional soccer players (Timmins et al, 2016b), although no such relationship was noted for Rugby players (Bourne et al, 2015). Meanwhile, athletes with a history of ACL injury or HSI display similar eccentric knee flexor weakness and shorter BFLongHead fascicle lengths in previously injured limbs compared to the uninjured contralateral limbs (Opar et al, 2015a;Timmins et al, 2016b).…”

“…Late-preseason deficits in eccentric knee flexor strength during the Nordic hamstring exercise are associated with a 4.3 to 4.4-fold increased risk of future hamstring injury in elite Australian rules footballers (Opar et al, 2015a) and professional soccer players (Timmins et al, 2016b), although no such relationship was noted for Rugby players (Bourne et al, 2015).…”

“…The proposed mechanisms for HSIs include kicking, tackling, cutting, stooping while running and excessive stretching (Brooks et al, 2006;Ekstrand & Gillquist, 1983;Verrall, Slavotinek, Barnes, & Fon, 2003;Woods et al, 2004). However, the majority of HSIs in running based sports occur during high-speed activities (Bourne, Opar, Williams, & Shield, 2015;Brooks et al, 2006;Opar et al, 2015a;Timmins et al, 2016b;Woods et al, 2004).…”

“…The goal of this study was to examine whether a history of ACLR was associated with an elevated risk of future hamstring strain injury. This study involved a secondary analysis of data collected in three previous prospective hamstring injury risk factor studies of male Australian rules football (Opar et al, 2015a), soccer (Timmins et al, 2016b) and rugby (Bourne et al, 2015) players. By combining the results of each study, sufficient statistical power was obtained to examine relationships between prior ACLR and future HSI.…”

“…This study involved a secondary analysis of data collected in three previously published prospective studies (Bourne et al, 2015;Opar et al, 2015a;Timmins et al, 2016b) These injury reports were confirmed with information from each club's internal medical recording system. The type of ACLR was not recorded for the entire AFL cohort or some of the Rugby players.…”