Scardella A T, Krawciw N, Petrozzino J J, Co M A, Santiago T V, Edelman N H
Department of Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick 08903-0019.
Am Rev Respir Dis. 1993 Jul;148(1):179-84. doi: 10.1164/ajrccm/148.1.179.
Since activity of the genioglossus muscle plays a primary role in maintaining upper airway patency during sleep, its strength and endurance characteristics are of potential importance. The purpose of this study was 2-fold. First, to define the strength and endurance characteristics of the normal human genioglossus. Second, we hypothesized that because the genioglossus has a high proportion of fast glycolytic muscle fibers, brief periods of increased activity would make it more susceptible to fatigue. In five normal male subjects strength of the tongue was evaluated by measuring maximal anterior force using a transducer (Fmax). In each subject tongue endurance was then tested at 100%, 80%, and 50% Fmax. To test the effect of a short-term increase in genioglossal activity on its endurance, an inspiratory flow-resistive load with mild hypercapnia was presented to the upper airway for 10 min, after which genioglossal endurance at 80% Fmax was repeated. On a separate day the effect of inspiratory loading plus hypercapnia on thoracic inspiratory muscle endurance was also tested. Our results showed that mean Fmax was 1,267 +/- 125 (SEM) g. Endurance time (Tlim) decreased progressively during 50%, 80% and 100% Fmax trials. Short-term activation of the genioglossus caused a reduction in Tlim at 80% Fmax to 51.4 +/- 4.8% of its value before loading (p < 0.05). Tlim for the inspiratory muscles, however, was unaffected. We conclude that, like other skeletal muscles, genioglossal endurance is reduced as the force of contraction increases. In addition, genioglossal endurance is significantly reduced by short-term activation insufficient to fatigue the thoracic inspiratory muscles.
由于颏舌肌的活动在睡眠期间维持上呼吸道通畅方面起主要作用，其力量和耐力特性具有潜在重要性。本研究的目的有两个。第一，确定正常人类颏舌肌的力量和耐力特性。第二，我们假设由于颏舌肌含有高比例的快速糖酵解肌纤维，短暂的活动增加会使其更容易疲劳。在五名正常男性受试者中，通过使用传感器测量最大向前力（Fmax）来评估舌肌力量。然后在每个受试者中，分别以Fmax的100%、80%和50%测试舌肌耐力。为了测试颏舌肌活动短期增加对其耐力的影响，对上呼吸道施加吸气性气流阻力负荷并伴有轻度高碳酸血症，持续10分钟，之后重复在80%Fmax时的颏舌肌耐力测试。在另一天，还测试了吸气负荷加高碳酸血症对胸段吸气肌耐力的影响。我们的结果显示，平均Fmax为1267±125（SEM）克。在50%、80%和100%Fmax试验期间，耐力时间（Tlim）逐渐减少。颏舌肌的短期激活导致在80%Fmax时Tlim降至负荷前值的51.4±4.8%（p<0.05）。然而，吸气肌的Tlim未受影响。我们得出结论，与其他骨骼肌一样，颏舌肌的耐力随着收缩力的增加而降低。此外，颏舌肌的耐力会因短期激活而显著降低，而这种激活程度不足以使胸段吸气肌疲劳。
