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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)
STUDY DESIGN The electromyogram (EMG) from the in vivo feline L1 to the L7 multifidus was recorded during the application of a 20-minute static lumbar flexion and after 7 hours of rest. OBJECTIVE To determine the recovery of tension-relaxation and laxity in the lumbar viscoelastic structures as well as the recovery of reflexive EMG activity in the(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)
Surface and wire myoelectric activity of the medial gastrocnemius (MG), lateral gastrocnemius (LG) and tibialis anterior (TA) of the cat were recorded during supramaximal stimulation applied via their nerves before and after the muscle nerve to the LG and TA were cut in order to determine the amount of EMG crosstalk amongst neighbouring muscles. It was(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)
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)
STUDY DESIGN Electrical and mechanical stimulation of the lumbar supraspinous ligament of three patients with L4-L5 spinal deficits and of the feline model, respectively, was applied while recording electromyography on the multifidus muscles. OBJECTIVES To determine if mechanoreceptors in the human spine can reflexively recruit muscle force to stabilize(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)