Athletics Coach

Hamstring Injury

Proposed Causes and Prevention

acute hamstring injuries pose the greatest injury risk to elite and sub-elite sprinters (Woods et al., 2004; Edouard & Alonso; 2013; Askling et al.

2014). An examination of all injuries sustained at IAAF World Championships since 1987 suggests that acute hamstring injuries were responsible for approximately one quarter of all injuries in female sprinters and one third of all injuries for male sprinters. In addition to their prevalence, acute hamstring injuries also

Coaches need to be better educated... of the risks and causes of hamstring injuries...coaches have the potential to play an important role in the reduction [in the occurence] of hamstring injuries

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E

pidemiological studies have demonstrated that

Jean Alonso

required one of the longest recovery times of all injuries common to sprinters, significantly affecting training availability, competition preparation and sprinting performance (Askling, Saartok & Thorstensson, 2006; Askling et al., 2007). The most likely mechanism of acute hamstring injury during the sprinting action is a source of debate amongst scholars. The most commonly cited causes of hamstring injury in sprinters are detailed below:

Excessive Muscle Strain in Eccentric Contractions The original evidence for eccentric muscle contractions being

BELOW Phases of the running gait including the phases of hamstring eccentric contraction highlighted according to Yu et al. (2008)

the primary cause of hamstring injuries was originally based on research conducted in rabbits. Lieber & Friden et al. (1993) demonstrated that the primary cause of hamstring injury was not the quantity of force per se, but the magnitude of the strain during the period of eccentric muscle contraction. To understand how the finding of Lieber & Friden may relate to sprinting in humans, we can turn to

Wood

(1987),

who

studied

the

hamstring

muscle lengths, power, flexions and contractions during the running action. Wood demonstrated that the hamstring muscles contract eccentrically in the late swing phase and late stance phase of sprinting. Based on this finding, it was hypothesized that hamstring muscle strains are most likely to occur in the late swing phase prior to footstrike (Thelen et al., 2005) and in the late stance prior to takeoff. This was studied more recently by Yu et al. (2008), who concurred that the potential for hamstring injury exists during the late stance phase as well as during the late swing phase of sprinting. They added that the hamstring muscles were at a much longer length at the end of the swing phase, which may result in a higher risk of hamstring injury during this phase. Page 40/90

Impact

Drive

Stance

Recovery

Leap

Swing Eccentric Contraction

Large Eccentric Contraction