Schmidt Julianne D, Guskiewicz Kevin M, Blackburn J Troy, Mihalik Jason P, Siegmund Gunter P, Marshall Stephen W
Department of Kinesiology, University of Georgia, Athens, Georgia, USA
Matthew A. Gfeller Sport-Related Traumatic Brain Injury Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Injury Prevention Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Am J Sports Med. 2014 Sep;42(9):2056-66. doi: 10.1177/0363546514536685. Epub 2014 Jun 13.
An athlete is thought to reduce head acceleration after impact by contracting the cervical musculature, which increases the effective mass of the head.
To compare the odds of sustaining higher magnitude in-season head impacts between athletes with higher and lower preseason performance on cervical muscle characteristics.
Cohort study; Level of evidence, 2.
Forty-nine high school and collegiate American football players completed a preseason cervical testing protocol that included measures of cervical isometric strength, muscle size, and response to cervical perturbation. Head impact biomechanics were captured for each player using the Head Impact Telemetry System. A median split was used to categorize players as either high or low performers for each of the following outcome measures: isometric strength (peak torque, rate of torque development), muscle size (cross-sectional area), and response to cervical perturbation (stiffness, angular displacement, muscle onset latency). The odds of sustaining moderate and severe head impacts were computed against the reference odds of sustaining mild head impacts across cervical characteristic categorizations.
Linemen with stronger lateral flexors and composite cervical strength had about 1.75 times' increased odds of sustaining moderate linear head impacts rather than mild impacts compared with weaker linemen. Players who developed extensor torque more quickly had 2 times the increased odds of sustaining severe linear head impacts (odds ratio [OR], 2.10; 95% CI, 1.08-4.05) rather than mild head impacts. However, players with greater cervical stiffness had reduced odds of sustaining both moderate (OR, 0.77; 95% CI, 0.61-0.96) and severe (OR, 0.64; 95% CI, 0.46-0.89) head impacts compared with players with less cervical stiffness.
The study findings showed that greater cervical stiffness and less angular displacement after perturbation reduced the odds of sustaining higher magnitude head impacts; however, the findings did not show that players with stronger and larger neck muscles mitigate head impact severity.
人们认为运动员通过收缩颈部肌肉来降低撞击后的头部加速度，这会增加头部的有效质量。
比较季前颈部肌肉特征表现较高和较低的运动员在赛季中遭受更高强度头部撞击的几率。
队列研究；证据等级，2级。
49名高中和大学美式橄榄球运动员完成了一项季前颈部测试方案，该方案包括颈部等长力量、肌肉大小以及对颈部扰动的反应等测量。使用头部撞击遥测系统记录每名运动员的头部撞击生物力学数据。对于以下每项结果测量指标，采用中位数分割法将运动员分为表现高或低的两组：等长力量（峰值扭矩、扭矩发展速率）、肌肉大小（横截面积）以及对颈部扰动的反应（刚度、角位移、肌肉起始潜伏期）。针对颈部特征分类，计算遭受中度和重度头部撞击的几率与遭受轻度头部撞击的参考几率之比。
与较弱的线卫相比，侧屈肌和颈部综合力量较强的线卫遭受中度线性头部撞击而非轻度撞击的几率增加了约1.75倍。伸肌扭矩发展更快的运动员遭受严重线性头部撞击（比值比[OR]，2.10；95%可信区间，1.08 - 4.05）而非轻度头部撞击的几率增加了2倍。然而，与颈部刚度较小的运动员相比，颈部刚度较大的运动员遭受中度（OR，0.77；95%可信区间，0.61 - 0.96）和重度（OR，0.64；95%可信区间，0.46 - 0.89）头部撞击的几率降低。
研究结果表明，更大的颈部刚度和扰动后更小的角位移降低了遭受更高强度头部撞击的几率；然而，研究结果并未表明颈部肌肉更强壮、更大的运动员能减轻头部撞击的严重程度。
