Grimby G, Aniansson A, Hedberg M, Henning G B, Grangård U, Kvist H
Department of Rehabilitation Medicine, University of Göteborg, Sahlgren Hospital, Sweden.
J Appl Physiol (1985). 1992 Dec;73(6):2517-23. doi: 10.1152/jappl.1992.73.6.2517.
Nine men, 78-84 yr of age, participated in a dynamometer training program 2-3 times/wk, totaling 25 sessions, using voluntary maximal isometric, concentric, and eccentric right knee-extension actions (30 and 180 degrees/s). Measurements of muscle strength with a Kin-Com dynamometer and simultaneous electromyograms (EMG) were performed of both sides before and after the training period. Muscle biopsies were taken from the right vastus lateralis muscle. The total quadriceps cross-sectional area was measured with computerized tomography. Training led to an increase in maximal torque for concentric (10% at 30 degrees/s) and eccentric (13-19%) actions in the trained leg. The EMG activity increased at maximal eccentric activities. The total cross-sectional quadriceps area of the trained leg increased by 3%, but no changes were recorded in muscle fiber areas in these subjects, who already had large mean fiber areas (5.15 microns 2 x 10(3)). The fatigue index measured from 50 consecutive concentric contractions at 180 degrees/s decreased and the citrate synthase activity increased in all but one subject. The results demonstrate that increased neural activation accompanies an increase in muscle strength at least during eccentric action in already rather active elderly men and that muscle endurance may also be improved with training.
9名年龄在78至84岁之间的男性参加了一项测力计训练计划，每周进行2至3次训练，共25次，采用自愿性最大等长、向心和离心右膝伸展动作（30度/秒和180度/秒）。在训练期前后，使用Kin-Com测力计测量两侧肌肉力量并同步记录肌电图（EMG）。从右侧股外侧肌采集肌肉活检样本。用计算机断层扫描测量股四头肌的总横截面积。训练导致训练侧腿的向心动作（30度/秒时增加10%）和离心动作（增加13%至19%）的最大扭矩增加。在最大离心活动时，EMG活动增加。训练侧腿的股四头肌总横截面积增加了3%，但这些平均肌纤维面积已经很大（5.15平方微米×10³）的受试者的肌纤维面积没有变化。在180度/秒下连续进行50次向心收缩所测得的疲劳指数下降，除一名受试者外，所有受试者的柠檬酸合酶活性均增加。结果表明，在已经相当活跃的老年男性中，至少在离心动作期间，神经激活增加伴随着肌肉力量增加，并且训练也可能改善肌肉耐力。
