Hamstring Strain Injuries

Abstract

Hamstring strain injuries (HSIs) are common in a number of sports and incidence rates have not declined in recent times. Additionally, the high rate of recurrent injuries suggests that our current understanding of HSI and re-injury risk is incomplete. Whilst the multifactoral nature of HSIs is agreed upon by many, often individual risk factors and/or causes of injury are examined in isolation. This review aims to bring together the causes, risk factors and interventions associated with HSIs to better understand why HSIs are so prevalent. Running is often identified as the primary activity type for HSIs and given the high eccentric forces and moderate muscle strain placed on the hamstrings during running these factors are considered to be part of the aetiology of HSIs. However, the exact causes of HSIs remain unknown and whilst eccentric contraction and muscle strain purportedly play a role, accumulated muscle damage and/or a single injurious event may also contribute. Potentially, all of these factors interact to varying degrees depending on the injurious activity type (i.e. running, kicking). Furthermore, anatomical factors, such as the biarticular organization, the dual innervations of biceps femoris (BF), fibre type distribution, muscle architecture and the degree of anterior pelvic tilt, have all been implicated. Each of these variables impact upon HSI risk via a number of different mechanisms that include increasing hamstring muscle strain and altering the susceptibility of the hamstrings to muscle damage. Reported risk factors for HSIs include age, previous injury, ethnicity, strength imbalances, flexibility and fatigue. Of these, little is known, definitively, about why previous injury increases the risk of future HSIs. Nevertheless, interventions put in place to reduce the incidence of HSIs by addressing modifiable risk factors have focused primarily on increasing eccentric strength, correcting strength imbalances and improving flexibility. The response to these intervention programmes has been mixed with varied levels of success reported. A conceptual framework is presented suggesting that neuromuscular inhibition following HSIs may impede the rehabilitation process and subsequently lead to maladaptation of hamstring muscle structure and function, including preferentially eccentric weakness, atrophy of the previously injured muscles and alterations in the angle of peak knee flexor torque. This remains an area for future research and practitioners need to remain aware of the multifactoral nature of HSIs if injury rates are to decline.

Hamstring Strain in Soccer Players: Things the Trainer Must Know

“…When the hip joint is in flexion and the knee joint is in full extension, as while sprinting or kicking a ball, the group of muscles reaches maximal extension, which in certain cases may cause minute damage. This damage may be cumulative and worsen due to frequent activity at high intensity [18].…”

Volitional Hamstring Force Production During Closed Kinetic Chain Lower Extremity Exercise in Supine Position: A Randomized Controlled Trial

“…The hamstring muscle group is most often injured during high-speed propulsion activities most notably among track runners, football players and hockey players. Consequently, the biceps femoris in particular is considerably vulnerable to strain or injury during moments of acceleration [3][4][5]. Heiderscheit et al [6] further noted that the incidence of hamstring re-injury can be attributed to chronic musculotendinous shortening secondary to previous injury [6].…”

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

“…The BFLongHead experiences the greatest strain and this may explain why this muscle is most commonly injured compared to SM and ST during high-speed running (Koulouris, Connell, Brukner, & Schneider-Kolsky, 2007). The hamstrings undergo some level of stress and strain when they are active and therefore whenever the magnitude of either is high enough a HSI will occur (Opar, Williams, & Shield, 2012). …”

“…The mechanism(s) increasing the risk of future HSI in individuals with a history of this injury remain unclear; however, it is likely to occur from the contribution of a number of maladaptation's following HSI (Fyfe, Opar, Williams, & Shield, 2013;Opar et al, 2012) or the persistence of risk factors that contributed to the initial injury (Croisier, Forthomme, Namurois, Vanderthommen, & Crielaard, 2002;Silder, Heiderscheit, Thelen, Enright, & Tuite, 2008;Witvrouw et al, 2003).…”

“…There have been a number of retrospective observations made in relation to the maladaptations following injury, such as; the formation of non-functional scar tissue which impacts muscle tissue lengthening mechanics (Silder, Reeder, & Thelen, 2010), reduced flexibility (Jonhagen, Nemeth, & Eriksson, 1994), chronic reductions in eccentric strength (Croisier et al, 2002;Jonhagen et al, 1994;Lee, Reid, Elliott, & Lloyd, 2009), chronic atrophy of the injured muscle (Silder et al, 2008), alterations in the angle of peak torque (Brockett, Morgan, & Proske, 2004) and lower limb biomechanics (Verrall et al, 2001), however, given the lack of prospective evidence it is difficult to determine if these factors are the cause of or the result of initial injury (Opar et al, 2012).…”