Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, 711 Washington Street, Boston, MA 02111, USA.
J Gerontol A Biol Sci Med Sci. 2010 May;65(5):495-502. doi: 10.1093/gerona/glq012. Epub 2010 Feb 15.
Age-related alterations of neuromuscular activation may contribute to deficits in muscle power and mobility function. This study assesses whether impaired activation of the agonist quadriceps and antagonist hamstrings, including amplitude- and velocity-dependent characteristics of activation, may explain differences in leg extension torque and power between healthy middle-aged, healthy older, and mobility-limited older adults.
Torque, power, and electromyography were recorded during maximal voluntary leg extension trials across a range of velocities on an isokinetic dynamometer.
Neuromuscular activation was similar between middle-aged and older healthy groups, with differences in torque and power explained predominantly by muscle size. However, the older mobility-limited group demonstrated marked impairment of torque, power, and agonist muscle activation, with the greatest deficits occurring at the fastest movement velocities. Agonist muscle activation was found to be strongly associated with torque output.
Similar neuromuscular activation between the middle-aged and older healthy groups indicates that impaired voluntary activation is not an obligatory consequence of aging. However, the finding that the mobility-limited group exhibited impaired activation of the agonist quadriceps and concomitant deficits in torque and power output suggests that neuromuscular activation deficits may contribute to compromised mobility function in older adults.
与年龄相关的神经肌肉激活改变可能导致肌肉力量和运动功能的缺陷。本研究评估了在健康中年、健康老年和行动受限老年人群中，股四头肌和拮抗腘绳肌的激活受损，包括激活的幅度和速度依赖性特征，是否可以解释伸膝力矩和功率的差异。
在等速测力计上，对最大自主伸膝试验进行了一系列速度的测试，记录了力矩、功率和肌电图。
中年和健康老年组的神经肌肉激活相似，力矩和功率的差异主要由肌肉大小解释。然而，行动受限的老年组表现出明显的力矩、功率和主动肌激活受损，在最快的运动速度下，损伤最大。发现主动肌激活与力矩输出密切相关。
中年和健康老年组之间相似的神经肌肉激活表明，受损的主动激活不是衰老的必然结果。然而，行动受限组表现出主动股四头肌激活受损，同时伴有力矩和功率输出的缺陷，这表明神经肌肉激活缺陷可能导致老年人大脑运动功能受损。
