Ang Björn, Linder Jan, Harms-Ringdahl Karin
Neurotec Department, Karolinska Institutet, Huddinge, Sweden
Aviat Space Environ Med. 2005 Apr;76(4):375-80.
Flight-induced neck pain at high Gz loads or during sustained rotary-wing missions may be caused by limitations in neck muscle function. A better understanding of the contributing factors of excessive external load and internal neck-stabilizing mechanisms would improve the ability to prevent and treat such pain. The aim of this single-blinded cross-sectional study was to evaluate neck neuromuscular function in fighter and helicopter pilots who suffered from frequent neck pain.
Subjects with pain were 16 fighter pilots (FP-P) and 15 helicopter pilots (HP-P) with frequent neck pain episodes who were compared with pain-free controls (FP-C and HP-C). In all groups, neck extensor and flexor muscles were studied by measuring 1) the strength of maximum voluntary contraction (MVC), and 2) fatigue due to a submaximal isometric contraction. The decline (slope) of the electromyogram (EMG) median frequency power spectra was used as an index of fatigue, while initial median frequency (fi) was taken from the intercept of the regression line.
Two-way analysis of variance (ANOVA) revealed interaction effects for extensor MVC. Post hoc testing showed that FP-P had significantly lower extensor MVC (p = 0.03) than FP-C, while there was no such difference for the HP-P vs. HP-C or between the two control groups. There were no significant effects for MVC-balance (flexors/extensors); nor were there any fi or extensor EMG-slope effects. However, there were interaction effects for flexor EMG-slopes: HP-P showed lower slopes than did HP-C (p = 0.02).
To protect and stabilize the head and neck in high Gz environments, higher neck muscle strength is needed; less muscle strength in FP-P may cause further pain and perhaps reduced mission effectiveness. Less localized steep slopes for HP-P might reflect impaired muscle functioning. Specific preventive and clinical attention may be warranted for different types of pilot.
在高过载（Gz）情况下或持续的旋翼机任务中，飞行引起的颈部疼痛可能是由颈部肌肉功能受限所致。更好地了解外部负荷过大的影响因素以及颈部内部稳定机制，将有助于提高预防和治疗此类疼痛的能力。这项单盲横断面研究的目的是评估经常遭受颈部疼痛的战斗机飞行员和直升机飞行员的颈部神经肌肉功能。
患有疼痛的受试者包括16名经常出现颈部疼痛发作的战斗机飞行员（FP-P）和15名直升机飞行员（HP-P），将他们与无疼痛对照组（FP-C和HP-C）进行比较。在所有组中，通过测量以下两项来研究颈部伸肌和屈肌：1）最大自主收缩（MVC）力量；2）次最大等长收缩引起的疲劳。肌电图（EMG）中频功率谱的下降（斜率）用作疲劳指标，而初始中频（fi）取自回归线的截距。
双向方差分析（ANOVA）显示伸肌MVC存在交互作用。事后检验表明，FP-P的伸肌MVC显著低于FP-C（p = 0.03），而HP-P与HP-C之间或两个对照组之间没有这种差异。MVC平衡（屈肌/伸肌）没有显著影响；fi或伸肌EMG斜率也没有任何影响。然而，屈肌EMG斜率存在交互作用：HP-P的斜率低于HP-C（p = 0.02）。
为了在高Gz环境中保护和稳定头部和颈部，需要更高的颈部肌肉力量；FP-P较低的肌肉力量可能会导致进一步疼痛，并可能降低任务效能。HP-P不太局部化的陡坡可能反映了肌肉功能受损。对于不同类型的飞行员，可能需要采取特定的预防措施并给予临床关注。
