Sbriccoli Paola, Solomonow Moshe, Zhou Bing-He, Lu Yun, Sellards Robert
Occupational Medicine Research Center, Bioengineering Laboratory, Department of Orthopaedic Surgery, Louisiana State University Health Sciences Center, 2025 Gravier Street, Suite 400, New Orleans, LA 70112, USA.
Am J Sports Med. 2005 Apr;33(4):543-51. doi: 10.1177/0363546504268408. Epub 2005 Feb 8.
Cyclic load applied to various joints during occupational and sports activities is epidemiologically linked to higher risk of neuromuscular disorder development.
Passive cyclic loading of the knee will develop laxity and creep in the anterior cruciate ligament, and these may elicit a neuromuscular disorder in the quadriceps and hamstrings. Women may be more susceptible to the disorder.
Controlled laboratory study.
Male and female groups were subjected to 10 minutes of passive cyclic loading (0.1 Hz) of the knee at a mild load (150-200 N) and at 35 degrees and 90 degrees flexion. Anterior tibial displacement and electromyogram from the quadriceps and hamstrings were monitored during cyclic loading. Maximal voluntary contraction of knee extension and flexion was assessed before and after cyclic loading. The effect of gender and angle on maximal voluntary contraction and quadriceps/hamstrings electromyogram was tested by a 2-way analysis of variance. Differences between the preload and postload data were tested by a paired t test.
At a knee angle of 90 degrees, after cyclic loading, a decrease in maximal voluntary contraction during extension was present in men and women, with an associated decrease in quadriceps electromyogram activity. At 35 degrees, a decrease in maximal voluntary contraction in extension was noted in women and men. Electromyogram spasms were present in the quadriceps and hamstrings during the 10-minute cyclic loading in 51.7% of subjects. Analysis of variance demonstrated that ligament creep was significantly greater in women than in men at both knee angles.
Even a mild cyclic loading of the anterior cruciate ligament, for a relatively short period, can elicit substantial creep, laxity, and a neuromuscular disorder. The disorder is composed of spasms and attenuated muscular function that may together create a condition that exposes the knee to injury. Women seem to be more susceptible than men.
Cyclic actions performed at high frequencies and high-load magnitudes may lead to the occurrence of increased knee laxity and changes in neuromuscular function that, together with fatigue and changes in proprioception, may increase the risk of injury.
在职业和体育活动中，施加于各个关节的周期性负荷在流行病学上与神经肌肉疾病发生风险较高相关。
膝关节的被动周期性负荷会导致前交叉韧带松弛和蠕变，而这可能引发股四头肌和腘绳肌的神经肌肉疾病。女性可能对该疾病更易感。
对照实验室研究。
男性和女性组在轻度负荷（150 - 200 N）下，于35度和90度屈膝位接受10分钟的膝关节被动周期性负荷（0.1 Hz）。在周期性负荷期间监测胫骨前移以及股四头肌和腘绳肌的肌电图。在周期性负荷前后评估膝关节屈伸的最大自主收缩。通过双向方差分析测试性别和角度对最大自主收缩以及股四头肌/腘绳肌肌电图的影响。通过配对t检验测试负荷前和负荷后数据的差异。
在90度膝关节角度时，周期性负荷后，男性和女性在伸展时的最大自主收缩均降低，同时股四头肌肌电图活动也相应降低。在35度时，男性和女性在伸展时的最大自主收缩均降低。在51.7%的受试者中，在10分钟的周期性负荷期间，股四头肌和腘绳肌出现肌电图痉挛。方差分析表明，在两个膝关节角度下，女性韧带蠕变均显著大于男性。
即使前交叉韧带承受相对较短时间的轻度周期性负荷，也可引发明显的蠕变、松弛和神经肌肉疾病。该疾病由痉挛和肌肉功能减弱组成，可能共同造成一种使膝关节易受伤 的状况。女性似乎比男性更易感。
高频和高负荷量的周期性动作可能导致膝关节松弛增加以及神经肌肉功能改变，这些与疲劳和本体感觉变化一起，可能增加受伤风险。
