Butcher M T, Hermanson J W, Ducharme N G, Mitchell L M, Soderholm L V, Bertram J E A
Department of Biological Sciences, 132 Long Hall, Clemson University, Clemson, South Carolina 29634, USA.
Equine Vet J. 2007 Nov;39(6):540-5. doi: 10.2746/042516407X212475.
Racing and training related lesions of the forelimb superficial digital flexor tendon are a common career ending injury to racehorses but aetiology and/or predisposing causes of the injury are not completely understood.
Although the injury takes place within the tendon, the lesion must be considered within the context of the function of the complete suspensory system of the distal limb, including the associated muscles.
Both muscle and tendon function were investigated in vivo using implanted strain gauges in 3 Thoroughbred horses walking, trotting and cantering on a motorised treadmill. These data were combined with assessments of muscle architecture and fibre composition to arrive at an overview of the contribution of each muscle-tendon unit during locomotion.
The superficial digital flexor muscle has fatigue-resistant and high force production properties that allow its tendon to store and return elastic energy, predominantly at the trot. As running speed increases, deep digital flexor tendon force increases and it stabilises hyperextension of the fetlock, thus reinforcing the superficial digital flexor in limb load support. The deep digital flexor muscle has fast contracting properties that render it susceptible to fatigue.
Based on these measurements and supporting evidence from the literature, it is proposed that overloading of the superficial digital flexor tendon results from fatigue of the synergistic, faster contracting deep digital flexor muscle.
Future research investigating distal limb system function as a whole should help refine clinical diagnostic procedures and exercise training approaches that will lead to more effective prevention and treatment of digital flexor tendon injuries in equine athletes.
前肢浅屈肌腱与比赛和训练相关的损伤是赛马常见的职业生涯终结性损伤，但损伤的病因和/或诱发因素尚未完全明确。
尽管损伤发生在肌腱内，但必须从远端肢体完整悬韧带系统（包括相关肌肉）的功能角度来考虑该病变。
在3匹纯种马在电动跑步机上行走、小跑和慢跑时，使用植入式应变片对肌肉和肌腱功能进行体内研究。这些数据与肌肉结构和纤维组成的评估相结合，以全面了解每个肌肉-肌腱单元在运动过程中的作用。
浅屈肌具有抗疲劳和高力量产生特性，使其肌腱能够储存和回弹性能量，主要在小跑时。随着奔跑速度增加，深屈肌腱力量增加，它稳定了球节的过度伸展，从而在肢体负荷支撑中加强了浅屈肌。深屈肌具有快速收缩特性，使其易疲劳。
基于这些测量结果和文献中的支持证据，提出浅屈肌腱的过载是由协同的、收缩更快的深屈肌疲劳导致的。
未来对整个远端肢体系统功能的研究应有助于完善临床诊断程序和运动训练方法，从而更有效地预防和治疗马运动员的屈肌腱损伤。
