Mechanism of hamstring muscle strain injury in sprinting

Hamstring muscle strain injury is one of the most common injuries in sports involving sprinting and kicking.Hamstring muscle strain injuries occur at a high rate and have a high re-injury rate,which results in loss of training and competition time,which has a significant impact on the quality of life of the injured athletes.~1Preventing and rehabilitating hamstring muscle strain injury is an important task for clinicians and scientists in sports medicine.Understanding the mechanisms underlying hamstring injury is critical for developing appropriate strategies to prevent and rehabilitate hamstring injuries.Understanding the

Relationships among hamstring muscle optimal length and hamstring flexibility and strength

Background:Hamstring muscle strain injury(hamstring injury) due to excessive muscle strain is one of the most common injuries in sports.The relationships among hamstring muscle optimal lengths and hamstring flexibility and strength were unknown,which limited our understanding of risk factors for hamstring injury.This study was aimed at examining the relationships among hamstring muscle optimal length and flexibility and strength.Methods:Hamstring flexibility and isokinetic strength data and three-dimensional kinematic data for hamstring isokinetic tests were collected for11 male and 10 female recreational athletes.The maximal hamstring muscle forces,optimal lengths,and muscle lengths in standing were determined for each participant.Results:Hamstring muscle optimal lengths were significantly correlated to hamstring flexibility score and gender,but not to hamstring strength.The greater the flexibility score,the longer the hamstring muscle optimal length.With the same flexibility score,females tend to have shorter hamstring optimal muscle lengths compared to males.Hamstring flexibility score and hamstring strength were not correlated.Hamstring muscle optimal lengths were longer than but not significantly correlated to corresponding hamstring muscle lengths in standing.Conclusion:Hamstring flexibility may affect hamstring muscle maximum strain in movements.With similar hamstring flexibility,hamstring muscle maximal strain in a given movement may be different between genders.Hamstring muscle lengths in standing should not be used as an approximation of their optimal lengths in calculation of hamstring muscle strain in musculoskeletal system modeling.

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

Background:The 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.Methods:Ten 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.Results:The 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).Conclusion:A 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.

Biomechanical characteristics of an anterior cruciate ligament injury in javelin throwing

目的:理解标枪运动中前十字韧带的损伤机制以及与前十字韧带损伤相关的标枪技术。方法:受试者是一名高水平女子标枪运动员,她在健康状态下完成前3次实验。在最近一次的田径大会期间进行了第4次实验,这次试验中她的左膝存在非外力引起的前十字韧带损伤。我们采集到损伤和非损伤实验中的三维运动学数据并从标枪生物力学数据库中获得52名男子和54名女子高水平标枪运动员的相关数据。结果:损伤和非损伤相比,在前25%的投掷阶段后,受试者质心向前的速度更大,垂直方向的速度更小:投掷阶段前21%的过程中,受试者左膝屈曲角度和角速度都更小,但左膝外翻和内旋角度没有明显差异。在损伤实验投掷阶段30%时,摄影图像中显示出明显的胫骨前移;受试者左脚触地时,左膝屈曲角度和角速度以及在投掷阶段中左膝最大屈曲角度与数据库中52名男子和54名女子优秀标枪运动员的数据没有相关性。结论:研究中的前十字韧带损伤发生在投掷阶段的前30%,更可能是前25%。左腿膝关节屈曲角度小,导致硬着陆是损伤的主要原因。标枪运动员应弯曲膝关节进行软着陆,这样能帮助他们预防前十字韧带损伤而不影响运动表现。

足球运动中前十字韧带损伤:负载机制、风险因素及预防方案（英文）

足球运动中前十字韧带(ACL)损伤非常常见。了解ACL的负载机制以及造成ACL损伤的危险因素有助于设计有效的预防方案。本综述目的在于为足球运动员总结关于ACL负载机制、ACL损伤因素,以及当前关于ACL损伤预防方案的研究。文献表明,近端胫骨的剪切力引起的胫骨前移是最主要的ACL负载机制,并无证据表明膝外翻是ACL的主要负载机制。之前有关ACL损伤危险因素的研究大都忽视ACL负载机制,已确定的风险因素几乎都与ACL负载机制无关。关于球员ACL损伤预防方案的研究结果互不一致。现有的足球运动员ACL损伤预防方案依从性低、临床效果不佳。未来的研究迫切需要确定与球员ACL负载机制相关的、与ACL损伤有因果关系的危险因素,开发新的预防方案以提高临床依从性。

Comment on “The late swing and early stance of sprinting are most hazardous for hamstring injuries” by Liu et al.

We have carefully read the description of the proposed mechanisms of hamstring muscle strain injury by Liu et al.1and noticed that they suggest that hamstring strain injuries may be associated with extensive muscle force and occur during the early stance phase of sprinting when the hamstrings are thought to work concentrically.We did not find any evidence in our extensive literature review to support this