Electromyographic evaluation of therapeutic massage effect using multi-finger robot hand

Objective To survey cervical myoelectric signals during craniocervical flexion, neutral and extension postures, and to explore the evidence that proper head position can alleviate cervical muscle fatigue in a lateral recumbent position. Methods Surface electromyography (sEMG) signals were detected from the sternocleidomastoid, upper trapezius and erector spinae muscles of 30 young subjects bilaterally during craniocervical flexion,neutral and extension postures in the left lateral recumbent position. The integrated trace area (IEMG) and median frequency (MF) were estimated. Results The average IEMG of the sternocleidomastoid muscles was significantly lower in flexion than in extension bilaterally. The average IEMG of the erector spinae muscles was lower in extension than in flexion bilaterally, and the difference was again significant. The IEMGs of the upper trapezius muscle showed no significant difference on average in the three postures bilaterally. There was no significant MF difference in any of the muscles. Conclusions The muscles in the cervical back were less activated during craniocervical extension in a lateral recumbent position. A little cranicocervical extension is optimal while resting in a lateral recumbent position. Key words: Surface electromyography; Lateral recumbent position; Sternocleidomastoid muscle; Cervical erector spinae muscle; Upper trapezius muscle

Conduction velocity in ischemic muscle: effect on EMG frequency spectrum.

Control strategy of movement, especially in multiple joint, may alter as one of muscles fatigue. In archery, consistent and repeated movement is performed during whole practice session or in competition game. Therefore, an archer may easily change activation pattern if one of the major contributive muscles is fatigue. It has been wildly using median frequency (MF) of EMG signal as a examine way to muscle fatigue. PURPOSE: To investigate the strategy and fatigue state of upper back and shoulder girdle muscles during a whole practice session in elite and sub-elite archers. METHODS: Two archers with one won a gold medal of personal archery game in 2005 World University Games were recruited in this study. They performed on practice session with 144 arrows and rules simulated to formal competition with the duration was 2–3 hours approximately. Electromyographic (EMG) signals were recorded from upper trapezius (TRA), Infra-spinatus (INFRA), posterior teltoid (TEL), Rhomboid (RHOM), Latissimus dorsi (LAT) muscles on pull side of the body. Maximal voluntary isometric contraction (MVIC) before practice session was used to normalize EMG signal. Normalized root mean square (RMS) EMG and median frequency (MF) were calculated within one second by releasing an arrow which denned by accelerometers attached on wrist. The first and the last 3 sets with 18 trials (n=1 8) individually (6 trials per set) were compared. T-test for repeated measures was used. RESULTS: Significant decrease in MF in INFRA muscle (79±5 Hz vs. 59±6 Hz, p < 0.05) was demonstrated on sub-elite archer during the session. In elite one, it revealed slightly shift in MF but not significant in INFRAmuscle. Besides, TEL, TRA, INTRA, RHOM and LAT muscles activities detected from sub-elite archer were significantly increased (21.0±4.6% vs. 25.8±5.0%; 33.1±4.1% vs. 34.5±5.7%; 26.3±5.0%vs. 36.1±5.0%; 21.6±3.0%vs. 27.7±4.6%; 17.5±2.4% VS.19.2±3.0% respectively, p < 0.05), but only INFRA muscle activity was increased significantly in elite one (17.6±2.2% vs. 19.6±2.7%, p < 0.05). CONCLUSION: Muscle fatigue did occur in sub-elite archer's INFRA muscle but not in elite one during a practice session. Muscle activation pattern would alter following one of the mainly muscle fatigue. The scientific information may offer the coach as a reference resource to avoid overtraining due to muscle fatigue.

: Muscle fatigue involves both a decrease in the frequency and increase in the amplitude of a surface electromyographic (SEMG) signal. Muscle fatigue is also related to a decrease of the force impeding to reach the same initial level of the maximum voluntary contraction (MVC). To determine indices of muscle fatigue, a method is proposed to estimate both the instantaneous frequency (IF) and the instantaneous amplitude (IA) by decomposing the SEMG signal using a filter bank. A linear regression model was adopted to compute the IF and IA slopes. These slopes were then classified in muscle increase force, recovery, muscle decrease force and fatigue by using a joint analysis of frequency and amplitude. SEMG signals were recorded from 26 normal human subjects when doing an exertion of 70% and 100% of their MVC during a session of eight hours. It was found that slopes derived from the proposed filter bank are equivalent to those slopes derived from the spectrogram and the smoothed pseudo Wigner-Ville distribution. Furthermore, slopes derived from the filter bank indicated that they can be used as indices to determine muscle fatigue. These results were confirmed by correlating indices of muscle fatigue with perceived levels of discomfort reported by the subjects after performing an exertion of 70% MVC in hours two, four, and six.

This study presents a frequency analysis of surface electromyogram (EMG) signals acquired by a linear electrode array from the biceps brachii muscles bilaterally in 14 hemiparetic stroke subjects. For different levels of isometric contraction ranging from 10 to 80% of the maximum voluntary contraction (MVC), the power spectra of 19 bipolar surface EMG channels arranged proximally to distally along the muscle fibers were examined in both paretic and contralateral muscles. It was found that across all stroke subjects, the median frequency (MF) and the mean power frequency (MPF), averaged from different surface EMG channels, were significantly smaller in the paretic muscle compared to the contralateral muscle at each of the matched percent MVC contractions. The muscle fiber conduction velocity (MFCV) was significantly slower in the paretic muscle than in the contralateral muscle. No significant correlation between the averaged MF, MPF, or MFCV vs. torque was found in both paretic and contralateral muscles. However, there was a significant positive correlation between the global MFCV and MF. Examination of individual EMG channels showed that electrodes closest to the estimated muscle innervation zones produced surface EMG signals with significantly higher MF and MPF than more proximal or distal locations in both paretic and contralateral sides. These findings suggest complex central and peripheral neuromuscular alterations (such as selective loss of large motor units, disordered control of motor units, increased motor unit synchronization, and atrophy of muscle fibers, etc.) which can collectively influence the surface EMG signals. The frequency difference with regard to the innervation zone also confirms the relevance of electrode position in surface EMG analysis.

This study presents the classification of cervical disc herniation patient and healthy persons by using muscle fatigue information. Cervical disc herniation patients suffer from neck pain and muscle fatigue in the neck increases these aches. Neck pain is the most common pain type encountered after back pain. The discomforts that occur in the neck region affect the daily quality of life, so the number of researches done in this area is increasing. In this study surface Electromyography (EMG) signals were used to examine muscle fatigue. EMG signals were obtained from Trapezius and Sternocleidomastoid (SCM) muscles in the cervical region of 10 control subject and 10 cervical disc herniation patients. Surface EMG was preferred because it is a noninvasive method. In the first step of this study, EMG signals were filtered and adapted for analysis. In the second step, muscle fatigue was determined using Median and Mean frequency values obtained by Fourier Transform and Welch methods. Feature extraction was the third step which was performed by Short Time Fourier Transform (STFT), Discrete Wavelet Transform (DWT) and Autoregressive method (AR). Finally, Artificial Neural Network (ANN) was used for classification. Training and test data were created by using feature vectors to classify patients with ANN. According to the results, the superior feature extraction method was investigated on patient classification using muscle fatigue information. The best results were obtained by AR method with %99 classification accuracy. Also, the best results were obtained by DWT with %100 classification accuracy for SCM muscle. This study has contributed that AR and DWT are a suitable feature extraction methods for surface EMG signals by providing high accuracy classification with artificial intelligence methods for cervical disc herniation disease. Besides, it is shown that muscle fatigue distinguishes cervical disc herniation patients from healthy people.

Detection of surface electromyography recording time interval without muscle fatigue effect for biceps brachii muscle during maximum voluntary contraction

Spectral parameters such as the mean and median frequencies have been documented to be reliable outcome variables for the assessment of muscle fatigue. The objective of this paper is to examine young subjects' surface electromyography (EMG) signals at different levels of maximum voluntary contractions (MVC) and to analyze spectral shifts in mean and median frequencies (MNF, MDF). In this study, continuous stream of EMG data sets from lower extremity muscles are used to characterize muscular fatigue from minimum to maximum MVC level. EMG data were recorded from the biceps brachii muscles during isometric contraction at constant torque levels using automated dynamometer. EMG metrics such as MNF, MDF, root mean square (RMS), and rectified root mean square (RRMS) were computed to assess muscle fatigue patterns.

Wheelchair basketball is the most popular exercise activity among individuals with spinal cord injury (SCI). The purpose of this study was to investigate muscular endurance and fatigue in wheelchair basketball athletes with SCI using surface electromyography (SEMG) and maximal torque values. SEMG characteristics of 10 wheelchair basketball players (WBP) were compared to 13 able-bodied basketball players and 12 sedentary able-bodied subjects. Participants performed sustained isometric elbow flexion at 50% maximal voluntary contraction until exhaustion. Elbow flexion torque and SEMG signals were recorded from three elbow flexor muscles: biceps brachii longus, biceps brachii brevis and brachioradialis. SEMG signals were clustered into 0.5-s epochs with 50% overlap. Root mean square (RMS) and median frequency (MDF) of SEMG signals were calculated for each muscle and epoch as traditional fatigue monitoring. Recurrence quantification analysis was used to extract the percentage of determinism (%DET) of SEMG signals. The slope of the %DET for basketball players and WBP showed slower increase with time than the sedentary able-bodied control group for three different elbow flexor muscles, while no difference was observed for the slope of the %DET between basketball and WBP. This result indicated that the athletes are less fatigable during the task effort than the nonathletes. Normalized MDF slope decay exhibited similar results between the groups as %DET, while the slope of the normalized RMS failed to show any significant differences among the groups (p>0.05). MDF and %DET could be useful for the evaluation of muscle fatigue in wheelchair basketball training. No conclusions about special training for WBP could be determined.

Assessment of muscle fatigue using sonomyography: Muscle thickness change detected from ultrasound images

Surface electromyography is a method which is for the evaluation of the electrical activity of superficial muscles. Moreover, muscle fatigue can also be detected using surface electromyography. In this study, on 20 volunteers, the muscle fatigue in cervical region was examined using surface electromyogram signals obtained from the trapezius and sternocleidomastoid muscle. Median frequency, mean frequency and mode frequency values were calculated by Welch method to investigate the muscle fatigue. When the Trapezius and sternocleidomastoid muscles are gone from study status to fatigue status the frequency parameters have shifted towards low frequencies. In practice, the median and mean frequency values are reliable parameters for muscle fatigue. According to the results; while the muscle fatigue was observed in 27 records for the median frequency, it was occurred in 22 records for the average frequency.

The relationship between EMG median frequency and low frequency band amplitude changes at different levels of muscle capacity

Effect of surgical radiation personal protective equipment on EMG-based measures of back and shoulder muscle fatigue: A laboratory study of novices

Establishment of a recording method for surface electromyography in the iliopsoas muscle

The aim of this randomized controlled crossover study was to investigate the effect of a bout of unaccustomed eccentric exercise (ECC) followed by a consecutive bout of the same intensity on local muscle blood flow, amplitude, and frequency of the electromyographic (EMG) signal from the exercised tibialis anterior muscle. Sixteen healthy male participants (age, 25.7 (0.6) years; body mass index 24.8 (1) kg·m(-2) participated in this study. Two identical bouts of high-intensity ECC were performed on the tibialis anterior muscle 7 days apart. Control sessions involving no exercise were performed 4 weeks either before or after the exercise sessions. Changes in local total blood flow [ΔtHb], EMG root mean square, and median power frequency were recorded during isometric maximum voluntary contraction of ankle dorsiflexion. Measurements were performed before, immediately after, and the day after both ECCs (ECC1 and ECC2). The participants rested quietly in a chair in the control session. Eccentric exercise 1 led to a significant decrease in [ΔtHb] on the day after (p ≤ 0.05), whereas ECC2 did not. Median power frequency decreased significantly in ECC2 compared with ECC1 (p < 0.01). Root mean square was unchanged in all the instants. The present study showed that adaptation is depicted in the local muscle blood flow and the frequency contents of the EMG after an unaccustomed ECC inducing muscle soreness. These alterations provide a potential mechanism for a rapid adaptation, which decreases susceptibility of the muscle to develop further soreness in the subsequent ECC bout.