Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest
Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest
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DOI：
10.1152/ajpregu.00761.2007
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发表时间：
2008-03-01
影响因子：
2.8
通讯作者：
Trappe, Todd
中科院分区：
文献类型：
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作者：
Trappe, Scott;Creer, Andrew;Trappe, Todd
比目鱼肌一直被证明在卸载期间比其他腿部肌肉萎缩得更多，并且难以使用各种锻炼对策范例来保护。然而，有氧运动，一种已知的氧化适应刺激的功效尚未与抗阻运动（RE），一种已知的肥大刺激相结合进行测试。我们假设，同时运动计划（AE + RE）将保留比目鱼肌纤维肌球蛋白重链（MHC）I的大小和功能在60天的卧床休息。第二个目的是检验富含亮氨酸的高蛋白饮食将部分保护比目鱼肌单纤维特征的假设。在对照组（BR; n = 7）、营养组（BRN; n = 8）和运动组（BRE; n = 6）卧床休息前后进行比目鱼肌活检。研究了单个肌纤维直径（Dia）、峰值力（P-o）、收缩速度和功率。BR降低（P <0.05）MHC I Dia（-14%）、Po（-38%）和功率（-39%），而收缩速度无变化。BRN的MHC I大小（-13%）和收缩功能（类似于30%）的变化与BR相似。BRE降低（P <0.05）MHC I Dia（-13%）和Po（-23%），而收缩速度增加（P <0.05）26%，并维持功率。这些比目鱼肌数据显示：1）AE + RE锻炼计划维持了MHC I的功率，但没有维持尺寸和强度，2）营养对策对单纤维尺寸和收缩功能没有益处。并行运动计划的大小和功能性MHC I比目鱼肌特性的不同反应是一个独特的发现，进一步突出了保护卸载比目鱼肌的挑战。
The soleus muscle has been consistently shown to atrophy more than other leg muscles during unloading and is difficult to protect using various exercise countermeasure paradigms. However, the efficacy of aerobic exercise, a known stimulus for oxidative adaptations, has not been tested in combination with resistance exercise (RE), a known hypertrophic stimulus. We hypothesized that a concurrent exercise program (AE + RE) would preserve soleus fiber myosin heavy chain (MHC) I size and function during 60 days of bed rest. A secondary objective was to test the hypothesis that a leucine-enriched high protein diet would partially protect soleus single fiber characteristics. Soleus muscle biopsies were obtained before and after bed rest from a control (BR; n = 7), nutrition (BRN; n = 8), and exercise (BRE; n = 6) group. Single muscle fiber diameter (Dia), peak force (P-o), contractile velocity, and power were studied. BR decreased (P < 0.05) MHC I Dia (-14%), Po (-38%), and power (-39%) with no change in contractile velocity. Changes in MHC I size (-13%) and contractile function (similar to 30%) from BRN were similar to BR. BRE decreased (P < 0.05) MHC I Dia (-13%) and Po (-23%), while contractile velocity increased (P < 0.05) 26% and maintained power. These soleus muscle data show 1) the AE + RE exercise program maintained MHC I power but not size and strength, and 2) the nutrition countermeasure did not benefit single fiber size and contractile function. The divergent response in size and functional MHC I soleus properties with the concurrent exercise program was a unique finding further highlighting the challenges of protecting the unloaded soleus.