The effect of hamstring flexibility on peak hamstring muscle strain in sprinting

Abstract

BackgroundThe effect of hamstring flexibility on the peak hamstring muscle strains in sprinting, until now, remained unknown, which limited our understanding of risk factors of hamstring muscle strain injury (hamstring injury). As a continuation of our previous study, this study was aimed to examine the relationship between hamstring flexibility and peak hamstring muscle strains in sprinting.MethodsTen male and 10 female college students participated in this study. Hamstring flexibility, isokinetic strength data, three-dimensional (3D) kinematic data in a hamstring isokinetic test, and kinematic data in a sprinting test were collected for each participant. The optimal hamstring muscle lengths and peak hamstring muscle strains in sprinting were determined for each participant.ResultsThe muscle strain of each of the 3 biarticulated hamstring muscles reached a peak during the late swing phase. Peak hamstring muscle strains were negatively correlated to hamstring flexibility (0.1179 ≤ R2 ≤ 0.4519, p = 0.001) but not to hip and knee joint positions at the time of peak hamstring muscle strains. Peak hamstring muscle strains were not different for different genders. Peak muscle strains of biceps long head (0.071 ± 0.059) and semitendinosus (0.070 ± 0.055) were significantly greater than that of semimembranosus (0.064 ± 0.054).ConclusionA potential for hamstring injury exists during the late swing phase of sprinting. Peak hamstring muscle strains in sprinting are negatively correlated to hamstring flexibility across individuals. The magnitude of peak muscle strains is different among hamstring muscles in sprinting, which may explain the different injury rate among hamstring muscles.

Late swing or early stance? A narrative review of hamstring injury mechanisms during high‐speed running

“…Several studies have reported peak lengthening velocity at the transition from knee flexion to extension, and a second, smaller peak in lengthening velocity has been described closer to terminal swing . During terminal swing, the BFlh reaches peak length and strain at approximately 112% of upright standing muscle length . Just prior to foot strike, the BFlh starts to shorten as the hip extends and the knee flexes in preparation for foot strike .…”

“…17 During terminal swing, the BFlh reaches peak length and strain at approximately 112% of upright standing muscle length. [17][18][19]22,52 Just prior to foot strike, the BFlh starts to shorten as the hip extends and the knee flexes in preparation for foot strike. [17][18][19]49 The hip continues to extend throughout stance, and the knee flexes for the first half, before starting to extend.…”

“…Advances in musculo‐skeletal modeling techniques over the past decade have facilitated several investigations into hamstring musculotendon mechanics during high‐speed running. These modeling studies have indicated that the mechanism of injury may relate to the timing of peaks in musculotendon variables such as length and force . These peaks occur in distinct phases of the gait cycle in response to the task demands.…”

“…These modeling studies have indicated that the mechanism of injury may relate to the timing of peaks in musculotendon variables such as length and force. 17,[19][20][21][22][23][24] These peaks occur in distinct phases of the gait cycle in response to the task demands. Two distinct arguments have been proposed for the timing of injury and pose the question: Do hamstring injuries occur during late swing or early stance?…”

Effects of flexibility and strength interventions on optimal lengths of hamstring muscle-tendon units

“…12 The follow-up study further demonstrated that peak strains of hamstring muscle-tendon units in sprinting were significantly correlated to hamstring optimal lengths and flexibility score. 13 These studies support hamstring flexibility as a predicator of peak strains in sprinting. However, due to the cross-sectional nature of previous investigations, these studies did not provide any evidence that hamstring optimal lengths could be altered by altering hamstring flexibility.…”