A comparison of electrical activity in the triceps surae at maximum isometric contraction with the knee and ankle at various angles

Abstract

The purpose of this study was to test the endurance of the soleus muscle, and to examine the joint position at which it is most active, while simultaneously suppressing the activity of the gastrocnemius. Ten young males performed maximum isometric contraction of the triceps surae for 100 s, and the endurance and plantar flexion torque of this muscle were measured at various angles of the knee and ankle joints. The electromyogram was measured simultaneously and subsequently converted into integrated electromyogram (IEMG) values. With the knee flexed at 130 degrees, the rate of change in IEMG values for the soleus (0.454% x s(-1)) with the ankle in a neutral position was significantly higher than that for the medial and lateral gastrocnemius. Both with the ankle dorsiflexed at 10 degrees and in the neutral position, the rate of change in IEMG for the soleus was significantly higher with the knee flexed at 90 degrees and 130 degrees than with the knee fully extended. With the knee flexed at 90 degrees and 130 degrees, the IEMG activity of the soleus during the initial (5-10 s) and final 5 s tended to be higher than those for the medial and lateral gastrocnemius, regardless of the ankle joint position. We conclude that the position in which the soleus acts most selectively during a sustained maximum isometric contraction of the triceps surae is with the ankle in a neutral position and the knee flexed at 130 degrees.

Fascicle behavior of medial gastrocnemius muscle in extended and flexed knee positions

“…5). This agrees with the earlier reports which examined the EMGs of MG under static (Cresswell et al, 1995;Miaki et al, 1999) and concentric (Carpentier et al, 1996(Carpentier et al, , 1999Price et al, 2003) conditions. In the case of surface EMG, the decrease in the MG EMG with knee flexion may be due to the impaired neuromuscular transmission or changes in electrode-muscle configuration (Cresswell et al, 1995).…”

Measurement and reproducibility of strength and voluntary activation of lower‐limb muscles

“…The maximal isometric torque measurements obtained in this study were similar to those previously published for the flexor and extensor muscles of the knee and ankle joint, with comparable joint positioning. 9,11,13,23,24,28,29,36 In some instances, authors reported the maximal isometric force or torque after only two contractions. 29,37 For accurate assessment of maximal strength, our results indicate that patients should perform five MVCs to ensure that the largest maximal torque is recorded.…”

The force–velocity relationship of the human soleus muscle during submaximal voluntary lengthening actions

“…As the CPN branches into the deep peroneal nerve that innervates dorsiflexor muscles such as TA, and the superficial peroneal nerve, that innervates the plantar flexor muscles PL and PB (Benzon et al 1997), the anaesthetic block of the CPN not only abolished activation of TA, but also removed activation of the synergist plantar flexors, PL and PB. The contribution of all muscles, other than the triceps surae, to plantar flexion torque is estimated to range between 15% and 38% (Arndt et al 1998;Gregor et al 1991;Miaki et al 1999;Murray et al 1976). Therefore, anaesthetic block of the CPN may account for a large proportion of the reduction in post-block torque by abolishing activation of the plantar flexor muscles, PL and PB.…”