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The synergistic action of the ACL and the thigh muscles in maintaining joint stability was studied experimentally. The EMG from the quadriceps and hamstring muscle groups was recorded and analyzed in three separate experimental procedures in which the knee was stressed. The test revealed that direct stress of the ACL has a moderate inhibitory effect on the(More)
The objective of this study was to quantify the coactivation patterns of the knee flexor and extensor muscles as part of continued efforts to identify the role of the antagonist muscles in maintaining joint stability. The simultaneous EMG from the flexor and extensor muscles of the knee were recorded during maximal effort, slow isokinetic contractions (15(More)
The electromyographic (EMG) coactivation patterns of the knee flexors and extensors when acting as antagonists were studied as a function of limb velocity to assess their contribution to joint stiffness and laxity. Normalized antagonist coactivation patterns developed from surface EMG recordings from the hamstrings and quadriceps during maximal effort(More)
STUDY DESIGN The recording of electromyographic responses from the in vivo lumbar multifidus of the cat, obtained while cyclic loading was applied as in occupational bending/lifting motion over time. OBJECTIVES To determine whether the effectiveness of stabilizing reflexive muscular activity diminishes during prolonged cyclic activity; the recovery of(More)
The biomechanics, histology and electromyography of the lumbar viscoelastic tissues and multifidus muscles of the in vivo feline were investigated during 20 min of static as well as cyclic flexion under load control and during 7 h of rest following the flexion. It was shown that the creep developed in the viscoelastic tissues during the 20 min of static or(More)
STUDY DESIGN The electromyogram of the L1-L7 multifidus muscles of the in vivo cat were recorded while applying a prolonged steady displacement to the lumbar spine through the L4-L5 supraspinous ligament, simulating a moderate anterior flexion. OBJECTIVE To demonstrate that tension-relaxation and laxity of the viscoelastic structures (ligaments, discs,(More)
Electromyograms from the flexor and extensor muscles of normal human elbows were simultaneously recorded during maximal-effort isokinetic movement at 15 degrees/s over the joint's full range of motion. The antagonist electromyogram was normalized with respect to its electromyogram when acting as agonist at maximal effort and plotted as a function of joint(More)
The aim of this study was to compare the force (F) and the muscle transverse diameter changes during electrical stimulation of the motor nerve. In four cats the exposed motor nerves of the medial gastrocnemius were stimulated as follows: (a) eight separate trials at fixed firing rates (FR) from 5 to 50 Hz (9 s duration, supramaximal amplitude); (b) 5 to 50(More)
Three methods that can significantly reduce the variability of the EMG power density spectrum (PDS) variable by eliminating artifactual components are described. Two methods, one that allows the subtraction of power line noise in the time domain and one which allows the subtraction of system noise in the frequency domain from the EMG, were shown to be(More)
OBJECTIVE To assess the mechanical and neurological processes active in the development of a cumulative trauma disorder (CTD) associated with repetitive exposure to periods of static lumbar flexion. METHODS The spine of the feline model was subjected to a series of three 10 min sessions of static lumbar flexion with each session followed by a 10 min rest.(More)