Grabiner M D
Department of Biomedical Engineering, Cleveland Clinic Foundation, Ohio 44106.
J Appl Physiol (1985). 1994 Aug;77(2):807-11. doi: 10.1152/jappl.1994.77.2.807.
Nine subjects performed maximum contractions with the knee extensor muscles on an isokinetic device set at 4.36 rad/s. The knee extensions were preceded by isometric conditioning contractions of the antagonist knee flexor muscles. The conditioning contraction forces were 0, 25, 50, 75, and 100% of the maximum isometric force. The purpose of the study was to determine 1) the effects of graded conditioning contractions with the knee flexor muscles on the maximum performance of the quadriceps femoris and 2) whether the effects of the conditioning contractions are similarly distributed to components of the quadriceps femoris. The increased initial quadriceps femoris activation levels associated with the conditioning contractions were similarly distributed to quadriceps femoris components. In contrast with previously published research on exercise performed at substantially lower knee extension velocities, the maximum knee extension force and the work performed were not affected by the conditioning contractions. However, the maximum rate of force development increased significantly (P < 0.05). The intensity of the knee flexor conditioning contractions likely influences agonist motor unit activation variables, but this influence may be related to the speed of the agonist contraction.
九名受试者在等速装置上以4.36弧度/秒的速度进行了膝关节伸肌的最大收缩。在进行膝关节伸展之前，先对拮抗肌膝关节屈肌进行等长调节性收缩。调节性收缩力分别为最大等长力的0%、25%、50%、75%和100%。本研究目的是确定：1）膝关节屈肌分级调节性收缩对股四头肌最大表现的影响；2）调节性收缩的影响是否同样分布于股四头肌各组成部分。与调节性收缩相关的股四头肌初始激活水平增加，同样分布于股四头肌各组成部分。与之前发表的关于以低得多的膝关节伸展速度进行运动的研究相比，调节性收缩并未影响最大膝关节伸展力和做功。然而，最大力发展速率显著增加（P<0.05）。膝关节屈肌调节性收缩的强度可能影响主动肌运动单位激活变量，但这种影响可能与主动肌收缩速度有关。
