Abstract：
:Muscle force can be transmitted via connective tissues to neighboring muscles. The goal of this research is to determine the extent to which this effects force summation between synergists during physiological conditions. This manuscript reviews two studies examining the interaction between synergists in cat hindlimb. Deeply anesthetized cats were mounted in a rigid frame with the foot secured to a six-degree-of-freedom load cell coupled to a robotic arm. Muscles were stimulated by implanted nerve cuff electrodes. In the first study, force summation was measured during isometric contractions. Interactions were studied between the lateral gastrocnemius (LG)/soleus (SOL) and the medial gastrocnemius (MG) as well as between rectus femoris and vastus lateralis. Invariably, nonlinear force summation was less than 10% of maximum force for all three translational directions and all three rotational directions. The second study investigated if force transmission from SOL fibers was affected by length changes of its two-joint synergists. Ankle plantar flexor moment, upon activation of only SOL, was measured for various knee angles (70 degrees -140 degrees ), which involved substantial length changes of LG, MG, and plantaris muscles. Ankle angle was kept constant (80 degrees -90 degrees ). SOL ankle moment was not significantly (P = 0.11) affected by changes in knee angle, neither were the half-relaxation time and the maximal rate of relaxation. The connective tissue links between SOL and LG were further studied during a tenotomy of the SOL and demonstrated that the connective links can transmit approximately 50% of the force from the SOL to the LG in nonphysiological conditions. In conclusion, despite strong connective tissue linkages, in cat hindlimb synergistic muscles appear to be independent actuators if acting in physiological conditions.
journal_name
Med Sci Sports Exercjournal_title
Medicine and science in sports and exerciseauthors
Sandercock TG,Maas Hdoi
10.1249/MSS.0b013e318183c0c3subject
Has Abstractpub_date
2009-01-01 00:00:00pages
184-90issue
1eissn
0195-9131issn
1530-0315journal_volume
41pub_type
杂志文章,评审abstract：:A biomechanical model of the ankle joint was developed and was used to predict the forces at the ankle during the stance phase of running. Measurements from five cadavers were averaged to obtain insertion points and directions of pull of equivalent tendons with respect to the assumed center of the ankle joint. A minim...
journal_title：Medicine and science in sports and exercise
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