Crisco J J, Hentel K D, Jackson W O, Goehner K, Jokl P
Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT 06520-1701, USA.
J Biomech. 1996 Oct;29(10):1291-6. doi: 10.1016/0021-9290(96)00047-4.
The effect of muscle contraction on a contusion injury model was studied in the gastrocnemius muscle of anesthetized rats. Both limbs of 18 rats received a contusion injury with a blunt non-penetrating impact. One hind limb was relaxed during impact and the other was electrically stimulated to tetanic contraction. The impact was produced using a drop-mass technique (mass = 171 g, height = 101 cm, spherical radius of impactor tip = 6.4 mm). The impact response was determined by sampling (10 kHz) the transmitted impact force and the displacement of the impactor. In a subgroup of nine rats, the severity of the contusion injury was measured by recording contractile tension in twitch and tetanus within two hours of injury. We found that the peak impact force was significantly less (p < 0.01), while the peak impact displacement was significantly greater (p < 0.01) in the contracted limb. Correspondingly, the impact stiffness of the contracted limb was significantly less (p < 0.01) than the impact stiffness in the relaxed limb. Both impacts produced significant injuries relative to an uninjured control group. The tetanic tension (31 +/- 4 N) generated by the muscles that were contracted during impact was significantly (p < 0.03) greater than that generated by the muscles that were relaxed during impact (27 +/- 4 N). The findings from this specific model indicate that the impact response of the limbs with relaxed muscle was dominated by the underlying bone, while maximally contracted muscle decreased the influence of the bone and lessened the impact response. Maximally contracted muscle was not more susceptible to injury and may act as protective mechanism against some impacts.
在麻醉大鼠的腓肠肌上研究了肌肉收缩对挫伤损伤模型的影响。18只大鼠的双下肢均受到钝性非穿透性撞击造成挫伤。撞击时，一条后肢处于松弛状态，另一条后肢则接受电刺激引发强直收缩。撞击采用落锤技术产生（质量 = 171克，高度 = 101厘米，撞击器尖端的球形半径 = 6.4毫米）。通过对传递的撞击力和撞击器位移进行采样（10千赫兹）来确定撞击反应。在一个由9只大鼠组成的亚组中，通过记录损伤后两小时内单收缩和强直收缩的收缩张力来测量挫伤损伤的严重程度。我们发现，收缩肢体的峰值撞击力显著更小（p < 0.01），而峰值撞击位移显著更大（p < 0.01）。相应地，收缩肢体的撞击刚度显著低于松弛肢体的撞击刚度（p < 0.01）。相对于未受伤的对照组，两种撞击均造成了显著损伤。撞击时收缩的肌肉产生的强直张力（31±4牛）显著大于撞击时松弛的肌肉产生的强直张力（27±4牛）（p < 0.03）。这个特定模型的研究结果表明，肌肉松弛的肢体的撞击反应主要由其下方的骨骼主导，而最大程度收缩的肌肉则减少了骨骼的影响并减轻了撞击反应。最大程度收缩的肌肉对损伤并不更敏感，可能起到了抵御某些撞击的保护机制的作用。
