Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, The University of North Carolina, Chapel Hill, North Carolina 27599-8605, USA.
Clin J Sport Med. 2011 Sep;21(5):416-21. doi: 10.1097/JSM.0B013E31822C8A5C.
To evaluate the effect of cervical muscle strength on head impact biomechanics.
Prospective cohort.
Field setting.
Thirty-seven volunteer ice hockey players (age = 15.0 ± 1.0 years, height = 173.5 ± 6.2 cm, mass = 66.6 ± 9.0 kg, playing experience = 2.9 ± 3.7 years).
Participants were equipped with accelerometer-instrumented helmets to collect head impact biomechanics (linear and rotational acceleration) throughout an entire playing season. Before the season, isometric cervical muscle strength was measured for the anterior neck flexors, anterolateral neck flexors, cervical rotators, posterolateral neck extensors, and upper trapezius. Data were analyzed using random intercept general mixed linear models, with each individual player as a repeating factor/cluster.
Dependent variables included linear and rotational head accelerations. Cervical strength data were categorized into tertiles, creating groups with high, moderate, and low strength. Strength measures were averaged and normalized to body mass.
Significant differences in cervical muscle strength existed across our strength groups (P < 0.05). No differences were observed in linear or rotational acceleration across strength groups for the anterior neck flexors (PLin = 0.399; PRot = 0.060), anterolateral neck flexors (PLin = 0.987; PRot = 0.579), cervical rotators (PLin = 0.136; PRot = 0.238), posterolateral neck extensors (PLin = 0.883; PRot = 0.101), or upper trapezius (PLin = 0.892; PRot = 0.689).
Our hypothesis that players with greater static neck strength would experience lower resultant head accelerations was not supported. This contradicts the notion that cervical muscle strength mitigates head impact acceleration. Because we evaluated cervical strength isometrically, future studies should consider dynamic (ie, isokinetic) methods in the context of head impact biomechanics.
评估颈部肌肉力量对头部撞击生物力学的影响。
前瞻性队列研究。
现场设置。
37 名志愿冰球运动员（年龄=15.0±1.0 岁，身高=173.5±6.2cm，体重=66.6±9.0kg，比赛经验=2.9±3.7 年）。
参与者配备加速度计头盔，以在整个赛季中收集头部撞击生物力学（线性和旋转加速度）数据。在赛季开始前，测量颈前屈肌、颈前外侧屈肌、颈旋转肌、颈后外侧伸肌和上斜方肌的等长颈部肌肉力量。使用随机截距一般混合线性模型进行数据分析，每位运动员作为重复因素/聚类。
因变量包括头部的线性和旋转加速度。颈椎力量数据分为三分位数，创建高、中、低力量组。力量测量值平均并归一化为体重。
在我们的力量组中，颈椎肌肉力量存在显著差异（P<0.05）。在前颈屈肌（PLin=0.399；PRot=0.060）、颈前外侧屈肌（PLin=0.987；PRot=0.579）、颈旋转肌（PLin=0.136；PRot=0.238）、颈后外侧伸肌（PLin=0.883；PRot=0.101）或上斜方肌（PLin=0.892；PRot=0.689）中，没有观察到力量组之间的线性或旋转加速度差异。
我们假设具有较大静态颈部力量的运动员会经历较低的头部加速度的假设未得到支持。这与颈部肌肉力量减轻头部撞击加速度的观点相矛盾。由于我们对颈椎力量进行了等长评估，因此未来的研究应考虑在头部撞击生物力学的背景下使用动态（即等动）方法。
