No abstract available.
Isometric Contraction*

In this paper, we studied a signal processing method which extracts each MUAP(motor unit action potential) from EMG(Electromyogram) interference pattern for clinical diagnostic purposes. First of all, differential digital filtering is selected for eliminating the spike components of the MUAP' s from the backgroud noise. And the algorithm identifies the spikes over the certanin threshold by template matching in frequency domain. After missing or false firing factor is cut off at the IPJ(inter pulse interval) histogram, we average the MUAP waveforms from the raw signal using the identified spikes as triggers, and finally, measure their amplitudes, durations, and numbers of phases. Specially, we introduce algorithm performed by template matching in the frequency domain. This algorithm performed as follows. A typical 3 second signal recorded from the biceps brachii muscle using a conventional needle electrode during a isometric contraction. And decomposed active MUAP' s decomposed from original EMG signal.
Electrodes ; Fibrinogen ; Fires ; Isometric Contraction ; Needles ; Noise

OBJECTIVE: The purpose of this study is to determine the proper hand position during driving by measuring of the wheel rotation strength according to the wheel angle and hand position to the wheel. METHOD: BTE Work Simulator was used to measure the clockwise and counter clockwise static wheel rotation force of twenty healthy men in three different hand position (2~10 spot, 3~9 spot, and 4~8 spot) and two different wheel angle (45 degrees and 60 degrees), average and peak force were measured during maximal isometric contraction. RESULTS: The average and peak force was significantly different by the wheel angle, and hand position (p<0.01), but the direction of rotation didn't an effect on the rotation force. The hand position was the most significant factor, especially wheel rotation force at 2~10 spot hand position was significantly lower than that of 3~9 spot and 4~8 spot (p<0.05). The rotation force by the wheel angle was influenced by hand position, and lower in 60 degrees wheel angle in the 2~10 spot (p<0.05). CONCLUSION: The rotation force of wheel was influenced by the hand position. Therefore proper hand position is recommended during driving to reduce muscle fatigue.
Hand* ; Humans ; Isometric Contraction ; Male ; Muscle Fatigue

PURPOSE: The aim of this study was to investigate the changes of contraction patterns and the differences of activities in trunk muscles during dynamic balance (multidirectional tilting exercise). METHODS: Eight physically active male subjects participated in the study. Tilting exercises were included by four directions (i.e., forward, backward, left, and right side), and were undertaken at three different tilting degrees (i.e., 10°, 20°, and 30°). They performed two occasions of tilting exercise, separated by 6-week time interval. Surface electromyography system was used for record of any signals produced by muscles which normalized as percentage of maximum voluntary isometric contraction. RESULTS: There were no statistically significant different interactive effects in any of muscles between two factors (time vs. degree). However, we identified significant main effects of degrees (among 10°, 20°, and 30°) in muscle activations during maintaining with forward tilting (left and right longissimus, multifidus), backward tilting (left and right rectus abdominis, external oblique), left side tilting (right rectus abdominis, external oblique, longissimus, multifidus), right side tilting (left rectus abdominis, external oblique, longissimus, multifidus). CONCLUSION: Findings from this study allow the multidirectional tilting exercise to be considered as suitable for ameliorate muscle balance by inducing co-contraction in trunk muscles.
Electromyography ; Exercise ; Humans ; Isometric Contraction ; Male ; Muscles ; Rectus Abdominis

OBJECTIVE: Reaction time is known to be longer for bilateral activities than for unilateral ones. However, bilateral isometric training is a common technique for motor recovery in relatively early stage of recovery following stroke. Moreover, few studies elucidated the response time of proximal arm muscle. This study was designed to investigate the effects of bilateral shoulder abduction on electromyographic (EMG) timing in hemiplegic subjects. METHOD: EMG signal of 18 subjects with hemiplegia was recorded during isometric contraction of shoulder abductor along the audible beep. Each subject performed three sets of contraction: unilateral contraction of each side and simultaneous bilateral contraction. EMG parameters included initiation delay, termination delay, and root mean square (RMS). RESULTS: When subjects performed bilateral contraction simultaneously, initiation and termination delays and RMS of paretic arm significantly increased in the affected arm than nonaffected side. Compared with unilateral contraction, initiation and termination delays did not differ significantly although RMS was significantly reduced. In addition, side-to-side difference of termination delay significantly decreased. CONCLUSION: These results demonstrated that bilateral isometric training of proximal arm muscle could be performed for motor recovery after stroke with no compromise of movement timing. Furthermore, movement control would be expected to be enhanced.
Arm* ; Electromyography ; Hemiplegia ; Humans ; Isometric Contraction ; Reaction Time ; Shoulder ; Stroke

OBJECTIVES: To determine the effect of facilitation on H reflex side-to-side amplitude ratio and to determine the effect of averaging under the assumption that an averaging could further stabilize the amplitude ratio in a facilitated condition. METHOD: FCR H reflex amplitude ratios of direct and averaged potentials were measured in fifty asymptomatic subjects under three conditions, during rest, during a constant 5 pound isometric contraction under the hand-dynamometer monitoring, and during a moderate constant isometric contraction under the electromyographer's verbal guidance. RESULTS: The lower limits of the amplitude ratios that encompass 97.5% of subjects by the percentile method under three conditions were as follows; (1) during the rest (n=37); 0.47 (direct) and 0.50 (average), (2) during the constant 5 pound isometric contraction under the hand- dynamometer monitoring; 0.47 (direct) and 0.48 (average), and (3) during the moderate constant isometric contraction under the electromyographer's verbal guidance; 0.48 (direct) and 0.46 (average), respectively. CONCLUSION: There seems to be no definite effect of facilitation and averaging on H reflex amplitude ratio. H reflex amplitude ratio measured in facilitated condition without averaging is still useful for the diagnosis of unilateral radiculopathy.
Diagnosis ; H-Reflex* ; Isometric Contraction ; Radiculopathy ; Upper Extremity

PURPOSE: The purpose of this study was to investigate the muscle activities of the brachioradialis and extensor carpi radialis longus according to the type of backhand stroke in badminton.METHODS: To measure the muscle activities, we used electromyography (EMG) equipment to measure EMG values by performing maximal voluntary contraction (MVC) of the forearm muscles, which depends on the type of backhand stroke. With these values, the %maximum voluntary isometric contraction values were obtained. The data were calculated using SPSS ver. 21.0 and one-way repeated measures analysis of variance with a post-hoc least significant difference test.RESULTS: In this study, the backhand clear achieved higher maximum muscle activity values than those by the backhand push, under clear, and drive in the brachioradialis. The backhand smash achieved higher maximum muscle activity values than those by the backhand push in the extensor carpi radialis longus.CONCLUSION: The backhand clear is associated with a higher injury rate than those associated with the backhand push, under clear, and drive. The backhand smash is associated with a higher rate of the occurrence of tennis elbow than that associated with the backhand push. To prevent injuries, it is considered that the forearm's strength, stretching before and after exercise, and sufficient time to rest are important.
Electromyography ; Forearm ; Isometric Contraction ; Muscles ; Racquet Sports ; Stroke ; Tennis Elbow

OBJECTIVE: To investigate the effect of distant muscle contraction on the sensory and motor nerve conduction and F-wave studies in stroke patients. METHOD: During isometric contraction of contralateral hand, sensory nerve action potential (SNAP), compound muscle action potential (CMAP) and F-wave of median nerve were recorded at submaximal and supramaximal stimulus intensity. The subject group consisted of 15 stroke patients and 10 control subjects. RESULTS: At submaximal stimulation, the amplitude and area of SNAP were significantly increased during muscle contraction in both groups (p <0.05). However there were no changes in parameters of SNAP and CMAP at supramaximal stimulation in both groups. The latency of F-wave was prolonged, and the amplitude was increased in the stroke group than those in the control group at resting state (p <0.05). The shortening of F-wave latency and increment of F-wave amplitude were observed in the control group during distant muscle contraction, but not in the stroke group. CONCLUSION: The distant muscle contraction might facilitate the nerve conduction. In addition F-wave elicited during voluntary contraction can be used as a monitor of upper motor neuron disorders.
Action Potentials ; Hand ; Humans ; Isometric Contraction ; Median Nerve ; Motor Neurons ; Muscle Contraction* ; Neural Conduction* ; Stroke*

OBJECTIVE: To investigate the association of the muscle contraction with gating of the sensory input at central and peripheral levels according to the intensity of muscle contraction and location of the muscles, somatosensory evoked potentials (SSEPs) studies were evaluated at different levels of isometric contraction in the different muscles. METHOD: Median nerve SSEPs were recorded at Erb's point and scalp in the ten healthy adult subjects with isometric contraction of ipsilateral abductor pollicis brevis (APB), ipsilateral abductor digiti minimi (ADM) and contralateral APB. Median nerve SSEPs were recorded in each of these conditions during precontraction, weak contraction, strong contraction and 4 minutes after contraction. RESULTS: 1) N9 amplitudes of median SSEPs recorded at Erb's point were augumented during weak contraction and these amplitude augumentations were statistically significant in the ipsilateral APB contraction (p<0.05). 2) N20 amplitudes recorded at scalp were inhibited during strong isometric contraction and these amplitude inhibitions were statistically significant in the ipsilateral APB contraction (p<0.05). 3) The latencies of N9 and N20 potentials were not significantly changed during isometric contraction. CONCLUSION: Therefore peripheral nervous system as well as central nervous system is responsible for gating, so the subject should be asked for the best relaxation possible for higher reliability of SSEPs.
Adult ; Central Nervous System ; Evoked Potentials, Somatosensory* ; Humans ; Isometric Contraction ; Median Nerve ; Muscle Contraction* ; Muscles ; Peripheral Nervous System ; Relaxation ; Scalp

Surface electromyogram in the lumbar paraspinal muscles was studied to evaluate back muscle impairment in twenty chronic low back pain patients and twenty control subjects. Turns-amplitude and power spectrum analysis of electromyographic signals were performed at different force levels during fatigue from sustained isometric contraction and recovery from fatigue in trunk extensor muscles. Results indicated that with increasing force level mean amplitude and Root Mean Square (RMS) values were increased, but mean and median frequencies increased initially until 20% Maximal Voluntary Contraction (MVC) and decreased tendency after then. Turns, mean amplitude, RMS, mean and median frequencies were all higher in control subject than those of low back pain patients. During sustained isometric contraction at 70% MVC, mean and median frequencies were linearly decreased, and the slopes were steeper in the patients group. Mean amplitude and RMS value showed decreased tendency during fatigue. During recovery from fatigue turns, mean and median frequencies increased especially in the first 3 minutes and nearly completely recovered in the 7~8 minutes in both patients and control groups. Therefore the mean amplitude and RMS value could be used as indicators of the level of muscle contraction and the mean and median frequencies reflect well the muscle fatigue in paralumbar muscle. These results validate the use of surface EMG spectral parameters as an objective measure of back muscle impairment in chronic low back pain patients.
Back Muscles* ; Back Pain ; Fatigue ; Humans ; Isometric Contraction ; Low Back Pain* ; Muscle Contraction ; Muscle Fatigue ; Muscles ; Paraspinal Muscles ; Spectrum Analysis