Gurchiek Reed D, Teplin Zachary, Falisse Antoine, Hicks Jennifer L, Delp Scott L
Department of Bioengineering, Stanford University, Stanford, CA.
Med Sci Sports Exerc. 2025 Mar 1;57(3):461-469. doi: 10.1249/MSS.0000000000003577. Epub 2024 Oct 24.
Hamstring injuries are common in field-based sports and reinjury rates are high. Recent evidence suggests that hamstring injuries often occur during accelerative running, but investigations of hamstring mechanics have primarily considered constant-speed running. Thus, our objective was to compare hamstring lengths and velocities between accelerative running and constant-speed running.
We recorded videos of 10 participants during six accelerative running trials and six constant-speed running trials. We used OpenCap to estimate body segment kinematics and a three-dimensional musculoskeletal model to compute peak length and step-average lengthening velocity of the biceps femoris (long head) muscle-tendon unit. We compared running conditions using linear mixed models with running speed as the independent variable.
At running speeds below 75% of top speed, accelerative running resulted in greater peak lengths than constant-speed running. For example, the peak hamstring muscle-tendon length when a person accelerated from running at only 50% of top speed was equivalent to running at a constant 88% of top speed. Lengthening velocities were greater during accelerative running at all running speeds. Differences in hip flexion kinematics drove the greater peak lengths and lengthening velocities observed in accelerative running.
Hamstrings are subjected to longer lengths and faster lengthening velocities in accelerative running than in constant-speed running. This provides a potential biomechanical perspective toward understanding the occurrence of hamstring injuries during acceleration. Our results suggest that coaches and sports medicine staff should consider the accelerative nature of running in addition to running speed to quantify exposure to high-risk circumstances with long lengths and fast lengthening velocities of the hamstrings.
腘绳肌损伤在田径类运动中很常见，且再损伤率很高。最近的证据表明，腘绳肌损伤常发生在加速跑过程中，但对腘绳肌力学的研究主要考虑的是匀速跑。因此，我们的目的是比较加速跑和匀速跑之间的腘绳肌长度和速度。
我们记录了10名参与者在6次加速跑试验和6次匀速跑试验中的视频。我们使用OpenCap来估计身体节段的运动学，并使用三维肌肉骨骼模型来计算股二头肌（长头）肌腱单元的峰值长度和步长平均延长速度。我们使用以跑步速度为自变量的线性混合模型来比较跑步条件。
在低于最高速度75%的跑步速度下，加速跑导致的峰值长度比匀速跑更大。例如，当一个人从仅以最高速度的50%跑步加速时，腘绳肌肌腱的峰值长度相当于以最高速度的88%匀速跑步时的长度。在所有跑步速度下，加速跑时的延长速度都更大。髋部屈曲运动学的差异导致了加速跑中观察到的更大的峰值长度和延长速度。
与匀速跑相比，腘绳肌在加速跑中会经历更长的长度和更快的延长速度。这为理解加速过程中腘绳肌损伤的发生提供了一个潜在的生物力学视角。我们的结果表明，教练和运动医学人员除了考虑跑步速度外，还应考虑跑步的加速性质，以量化腘绳肌处于长长度和快速延长速度的高风险情况的暴露程度。
