ABSTRACT
The paper describes a method aimed at providing objective diagnostic testing of skilled locomotor stereotypes. Bioelectric muscle activity indices and ground reaction force data are used to represent a movement structure, in a schematized way, using discrete states in time. Athletes were asked to perform one specific movement structure: a backward somersault from the standing position. Mathematical analyses of measured signals reveal the significance, for the skill level evaluation, of parameters reflecting the impulsive take-off force waveform and the symmetry in EMG activity of ankle extensor muscles, which therefore might be used as diagnostic criteria. Within technical limitations, this approach may also be applied to other locomotor patterns and possibly to monitor the progress in motorics in pathological locomotion. EMG telemetry could significantly enhance the method's scope.
Subject(s)
Movement Disorders/physiopathology , Movement/physiology , Adult , Biomechanical Phenomena , Electromyography , Humans , Muscles/physiologyABSTRACT
We have studied skilled human locomotions in sports gymnastics by measurement and analysis of ground reaction force and myoelectric signals. Assuming the quality of performance to be a skill level criterion acquired signals were mathematically analyzed via basic signal processing and cross-correlation methods. The study of backward somersault yielded quantitative criteria of performance, proposing an original measure-an inter-muscular cross-correlation function. Besides motor learning, the quantification of movement skill introduced here also relates to possible applications in biocybernetics, robotics and rehabilitation medicine.
Subject(s)
Gymnastics/physiology , Locomotion/physiology , Motor Skills/physiology , Cybernetics , Electromyography , Humans , Male , Movement , Muscle Contraction , Muscle, Skeletal/physiology , Neuromuscular Junction/physiology , Rehabilitation , Robotics , Rotation , Signal Processing, Computer-Assisted , Stress, Mechanical , Weight-BearingABSTRACT
The electric current leak through an unsealed connector or insulation break can be a source of problems in cardiac pacing. This study describes a method of leak detection. The underdrive inhibition test--chest wall stimulation with external stimulator (ES)--was used for this purpose. Three cutaneous electrodes (CE) were applied: the first one above the indifferent electrode, the second one above the suspected leak location, and the third one above the active electrode. Two inhibition thresholds (IT) were measured: the first one connecting ES on first CE and second CE, and the second one connecting ES on first CE and third CE. The inhibition threshold is the value of ES output charge at which the inhibition of implanted pacemaker occurs. The relation between two ITs, not the absolute value, is significant for leak estimation. The former should be at least five times higher than the latter, if there is no current leak. During the two years of follow-up of 541 patients, 272 measurements were performed. In 52 cases the connector leak was found-both ITs were approximately equal. Twenty-seven cases were confirmed by surgery for EOL pacemaker replacement; the intrusion of body fluid was evident. Five operations were indicated because of the leak problem: two--muscle twitching, one--loss of capture, one-undersensing, and one--insulation break with lead fracture. The method, although approximate, is a reliable qualitative estimation of leak.