Rack and Westbury (1969) showed that low frequency asynchronous stimulation of a muscle produces greater force compared to synchronous stimulation. This study tested the hypothesis that the difference results from the dynamic stretch of the common elastic elements. In 8 anaesthetized cats the soleus was attached to a servomechanism to control muscle length and record force. The ventral roots were divided into 4 bundles so each innervated approximately 1/4 of the soleus. The elasticity shared by each part of the muscle was estimated and the servomechanism programmed to compensate for its stretch. At each test frequency (5, 7.5, and 10 Hz) the muscle was stimulated by: 1) asynchronous stimulation; 2) synchronous stimulation; 3) summation of force with each part stimulated individually; and 4) summation with each part stimulated individually and the servomechanism mimicking tendon stretch during asynchronous stimulation. Muscle length was isometric except for protocol 4. The observed differences were small. The greatest difference occurred during stimulation at 5 Hz with muscle length on the ascending limb of the length-tension curve. Here, the average forces, normalized by asynchronous force, were: 1) asynchronous 100%; 2) synchronous 73%; 3) summation 110%; and 4) summation with stretch compensation 98%. The results support the hypothesis, and suggest that the common elasticity can be used to predict force gains from asynchronous stimulation.