Injury Biomechanics Laboratory, Department of Biomedical Engineering, Duke University, United States.
Injury Biomechanics Laboratory, Department of Biomedical Engineering, Duke University, United States.
J Sci Med Sport. 2019 Jun;22(6):667-671. doi: 10.1016/j.jsams.2019.01.009. Epub 2019 Jan 18.
Increased neck strength has been hypothesized to lower sports related concussion risk, but lacks experimental evidence. The goal is to investigate the role cervical muscle strength plays in blunt impact head kinematics and the biofidelity of common experimental neck conditions. We hypothesize head kinematics do not vary with neck activation due to low short term human head-to-neck coupling; because of the lack of coupling, free-head experimental conditions have higher biofidelity than Hybrid III necks.
Impacts were modeled using the Duke University Head and Neck Model. Four impact types were simulated with six neck conditions at eight impact positions. Peak resultant linear acceleration, peak resultant angular acceleration, Head Injury Criterion, and Head Impact Power compared concussion risk. To determine significance, maximum metric difference between activation states were compared to critical effect sizes (literature derived differences between mild and severe impact metrics).
Maximum differences between activation conditions did not exceed critical effect sizes. Kinematic differences from impact location and strength can be ten times cervical muscle activation differences. Hybrid III and free-head linear acceleration metrics were 6±1.0% lower and 12±1.5% higher than relaxed condition respectively. Hybrid III and free-head angular acceleration metrics were 12±4.0% higher and 2±2.7% lower than relaxed condition respectively.
Results from a validated neck model suggest increased cervical muscle force does not influence short term (<50ms) head kinematics in four athletically relevant scenarios. Impact location and magnitude influence head kinematics more than cervical muscle state. Biofidelic limitations of both Hybrid III and free-head experimental conditions must be considered.
增加颈部力量已被假设为降低与运动相关的脑震荡风险，但缺乏实验证据。目的是研究颈部肌肉力量在钝性冲击头部运动学中的作用以及常见实验颈部条件的生物逼真度。我们假设由于短期人类头部与颈部的耦合较低，头部运动学不会因颈部激活而变化；由于缺乏耦合，自由头部实验条件比 Hybrid III 颈部具有更高的生物逼真度。
使用杜克大学头部和颈部模型模拟冲击。在八个冲击位置模拟了四种冲击类型和六种颈部条件。比较了峰值合成线性加速度、峰值合成角加速度、头部损伤准则和头部冲击功率，以评估脑震荡风险。为了确定显著性，激活状态之间的最大度量差异与临界效应大小（文献中轻度和重度冲击度量之间的差异）进行了比较。
激活条件之间的最大差异不超过临界效应大小。冲击位置和强度引起的运动学差异可能是颈部肌肉激活差异的十倍。Hybrid III 和自由头部线性加速度指标分别比放松状态低 6±1.0%和高 12±1.5%。Hybrid III 和自由头部角加速度指标分别比放松状态高 12±4.0%和低 2±2.7%。
来自验证颈部模型的结果表明，在四种与运动相关的情况下，增加颈部肌肉力量不会影响短期（<50ms）头部运动学。冲击位置和幅度比颈部肌肉状态更能影响头部运动学。必须考虑 Hybrid III 和自由头部实验条件的生物逼真度限制。
