Effect of exercise on skeletal muscle. II. Contractile properties.
Effect of exercise on skeletal muscle. II. Contractile properties.
复制标题
运动对骨骼肌的影响。
DOI：
10.1152/jappl.1970.28.6.767
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发表时间：
1970
影响因子：
3.3
通讯作者：
J. Peter
中科院分区：
文献类型：
--
作者：
R. Barnard;V. Edgerton;J. Peter
BARNARD, R. JAMES, V. REGGIE EDGERTON, AND JB PETER. Effect of exercise on skeletal muscle. II. Contractile properties. J. Appl. Physiol. 28 (6): 767-770. 1970-Contractile properties were measured in the in situ gastrocnemius-plantaris muscle preparation of five control and five trained adult, male guinea pigs. The measurements included: time-to-peak tension, half-relaxation time, tetanic-fusion frequency, twitch-to-tetanus ratio, and maximum rate of tension development. Although the muscles from trained animals were known to have a significantly greater percentage of red fibers than the muscles from control animals, no significant differences were observed in the contractile properties. In situ tests with the muscles contracting at a rate of 5/set showed that the trained muscles were capable of maintaining a higher level of isometric tension over a 60-min period of contraction. No evidence for muscle hypertrophy was observed in the trained animals. It is concluded that the increase in endurance of the total organism as well as the in situ muscle preparation is not due to changes in the contractile properties of the muscles. training; twitch time; tetanic tension; histochemistryTHE HYPOTHESIS that motoneurons exert some “trophic” influence on the muscles which they innervate has received much attention in the past several years. The investigations of Buller and Eccles and their associates (4-6) have demonstrated the mutability of skeletal muscle as well as a trophic influence with their cross-innervation studies. A normally fast-contracting muscle became slower after innervation by a nerve from a normally slow-contracting muscle. These investigators(4) postulated that some “specific” chemical substance was released from the motoneuron and produced a trophic influence on the muscle. More recently Vrbova and her associates (17, 20) have postulated that the frequency of nervous activity may be the important factor or trophic influence which determines the characteristics of a muscle. Vrbova’s hypothesis is supported by the work of Fishback and Robbins (13) who found that with immo-bilization of knee and ankle joints the aggregate EMG activity of the soleus muscle was reduced to 5-l 5% of the control. After 4 weeks of immoblization the speed of contraction of the soleus increased. Salmons and Vrbova (17) found that the increase in speed of contraction of the soleus observed after tenotomy of the soleus and cordotomy could be prevented if the muscle was stimulated chronically after the operation. They also reported that chronic electrical stimulation of a fast-contracting muscle produced a prolongation in the contraction time.
