Short biceps femoris fascicles and eccentric knee flexor weakness increase the risk of hamstring injury in elite football (soccer): a prospective cohort study

Abstract

The presence of short BFlh fascicles and low levels of eccentric knee flexor strength in elite soccer players increases the risk of future HSI. The greater risk of a future HSI in older players or those with a previous HSI is reduced when they have longer BFlh fascicles and high levels of eccentric strength.

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

“…As mentioned above, recent evidence suggests that the effects of age on HSI risk may be countered by changes to one or more modifiable risk factors (Opar et al, 2015b;Timmins et al, 2016b). For example, elite Australian footballers older than 23 years are at a heightened risk of HSI if they display low levels of eccentric knee flexor strength, but the effects of age are significantly smaller in stronger players (Opar et al, 2015a;Timmins et al, 2016b).…”

“…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).…”

“…Non-modifiable risk factors include a history of HSI (Arnason et al, 2004;Gabbe, Bennell, Finch, Wajswelner, & Orchard, 2006;Hagglund et al, 2006;Verrall et al, 2001) and increasing age (Arnason et al, 2004;Hagglund et al, 2006;Woods et al, 2004). Modifiable risk factors include poor flexibility (Bradley & Portas, 2007;Henderson, Barnes, & Portas, 2010;Witvrouw, Danneels, Asselman, D'Have, & Cambier, 2003), hamstring muscle weakness (Aagaard et al, 1998;Askling, Karlsson, & Thorstensson, 2003;Brockett, Morgan, & Proske, 2001;Croisier, Ganteaume, Binet, Genty, & Ferret, 2008;Orchard, Marsden, Lord, & Garlick, 1997;Petersen, Thorborg, Nielsen, Budtz-Jorgensen, & Holmich, 2011;Yeung, Suen, & Yeung, 2009), muscle fatigue (Brooks et al, 2006;Ekstrand et al, 2011a;Woods et al, 2004) and short BFLongHead fascicles (Timmins et al, 2016b). A thorough understanding of the abovementioned risk factors is necessary for determining the training strategies required to reduce the risk of initial HSI or re-injury in athletes.…”

“…For example, elite Australian footballers older than 23 years are at a heightened risk of HSI if they display low levels of eccentric knee flexor strength, but the effects of age are significantly smaller in stronger players (Opar et al, 2015a;Timmins et al, 2016b). More recently, Timmins and colleagues (2016b) found that higher levels of eccentric knee flexor strength and longer BFLongHead fascicles reduced the risk of HSI in older elite soccer players.…”

“…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).…”