Bernardi M, Solomonow M, Baratta R V
Department of Orthopaedic Surgery, Louisiana State University Medical Center, New Orleans, USA.
Electromyogr Clin Neurophysiol. 1997 Jan-Feb;37(1):3-12.
The motor unit recruitment control strategy of the antagonist thigh muscles was determined during linearly increasing isometric flexion and extension of the knees. The median frequency (MF) of the power density spectrum of surface electromyograms recorded from eighteen subjects was used as an indicator of motor units recruitment. The results showed that different recruitment strategies were used by the muscles that are antagonist to each other. When quadriceps and hamstrings acted as agonist most of the motor units were recruited in a linear manner up to 60% of maximal voluntary contraction (MVC). When the muscles acted as antagonist, quadriceps motor units were recruited up to 40% MVC during flexion while during extension the antagonist hamstrings recruited motor units up to 60% MVC. In both muscles, when acting as antagonist, the MF decreased after the recruitment phase, whereas when functioning as agonists, the MF remained relatively constant past the recruitment phase. The results suggested that a single muscle can employ different motor units recruitment strategies in accord with the type of contraction it performs and while acting as an agonist muscle as well as an antagonist.
在膝关节等长屈伸呈线性增加的过程中，确定了大腿拮抗肌的运动单位募集控制策略。从18名受试者记录的表面肌电图功率密度谱的中位频率（MF）被用作运动单位募集的指标。结果表明，相互拮抗的肌肉采用了不同的募集策略。当股四头肌和腘绳肌作为主动肌时，大多数运动单位以线性方式募集，直至最大自主收缩（MVC）的60%。当这些肌肉作为拮抗肌时，股四头肌运动单位在屈曲时募集至MVC的40%，而在伸展时，拮抗的腘绳肌募集运动单位至MVC的60%。在这两块肌肉中，当作为拮抗肌时，MF在募集阶段后下降，而当作为主动肌时，MF在募集阶段后保持相对恒定。结果表明，单一肌肉可根据其执行的收缩类型以及作为主动肌和拮抗肌时采用不同的运动单位募集策略。
