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Objective To identify the effect of the repeatability of muscle activations on extraction of consistent motor modules across trials. Methods The activities of sixteen muscles in twelve subjects who consistently walked at a self-selected speed were recorded. The intraclass correlation coefficient (ICC) was used to identify inter-stride repeatability of muscle activities and motor modules. Based on the repeatability of muscle activation, three types of muscle sets were organized. Results The reliable set containing the muscles showed high ICC (>0.4), but the whole-body and mixed sets containing the muscles showed poor ICC (＜0.4). When motor modules were extracted from each set, the reliable set showed the highest repeatability of motor module extraction, but the whole-body and mixed sets presented significantly lower repeatability. Conclusions Greater repeatability of muscle activations result ed in consistent motor modules. Extraction of consistent motor modules was a critical issue, especially in real-time motion recognition based on muscle patterns.
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Objective To identify the effect of the repeatability of muscle activations on extraction of consistent motor modules across trials. Methods The activities of sixteen muscles in twelve subjects who consistently walked at a self-selected speed were recorded. The intraclass correlation coefficient (ICC) was used to identify inter-stride repeatability of muscle activities and motor modules. Based on the repeatability of muscle activation, three types of muscle sets were organized. Results The reliable set containing the muscles showed high ICC (>0.4), but the whole-body and mixed sets containing the muscles showed poor ICC (＜0.4). When motor modules were extracted from each set, the reliable set showed the highest repeatability of motor module extraction, but the whole-body and mixed sets presented significantly lower repeatability. Conclusions Greater repeatability of muscle activations result ed in consistent motor modules. Extraction of consistent motor modules was a critical issue, especially in real-time motion recognition based on muscle patterns.
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Risk factors for running injuries can be clustered into intrinsic factors and extrinsic factors. Intrinsic factors include human anatomy, history of previous injuries, sports biomechanics and human neuromuscular control, etc. Extrinsic factors include training method , running shoes and running surfaces, etc. Running surface is considered as one of the most potential risk factors for running injuries. This review summarized the findings on kinematics, kinetics, neuromuscular control and running injuries of lower extremity during running on different surfaces. In general, neuromuscular adjustment may contribute to kinematic adaption during running on different surfaces, and runners can adapt their kinetics and stiffness of lower extremity to achieve similar impact force. However, studies on biomechanical changes during running on different surfaces mainly focus on only one aspect of kinematics, kinetics and neuromuscular regulation. Further studies should focus on three-dimensional biomechanical analysis during running on different surfaces, as well as specific mechanisms of neuromuscular regulation for these biomechanical adjustments.
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The purpose of this study is to compare the road conditions (straight road, winding road and hill road) with the hand grip pressure force and muscle fatigue for male and female drivers. Ten subjects were participated in this study. The force measurement and electromyography (EMG) responses were taken and evaluated by using the tactile grip and pressure measurement (Grip System) and Electromyography (EMG) device. The result indicated that the winding road produced more muscle fatigue and high hand grip pressure force compared than downhill road, hill up road, and straight road for both male and female subjects. The result compared the muscle fatigue and hand grip pressure force between the first 15 minutes and last 15 minutes of driving activity. The muscle fatigue increasingly high for the last 15 minutes compared to first 15 minutes. However, the hand grip pressure forces become high during the winding road for first 15 minutes of driving session. The muscle fatigue become high as the hand grip pressure force value is high. Furthermore, the male drivers exert higher hand grip pressure force and higher muscle fatigue compared to female drivers. This study can be used as a guideline for the future studies, primarily in solving the driving fatigue problem among the Malaysian’s drivers. The method of this study could also be used for early detection of driver fatigue issues. Indirectly, the findings could reduce the number of car accidents in Malaysia.
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atigue is a common phenomenon in many medical and neurologic diseases. Understanding the origins of fatigue in these diseases is of great guiding significance in developing targeted interventions for muscle fatigue. In this review, the central origin (including all the supraspinal and spinal physiological phenomena capable of inducing a decrease in motoneuron excitation) and the peripheral origin (including neuromuscular transmission, propagation of action potentials in muscle, excitation-contraction coupling) of muscle fatigue were summarized. The methods of assessing the central or peripheral origin of muscle fatigue were discussed, including the direct measurement (maximal voluntary contraction force, twitch force) and the indirect tests (twitch interpolation, electromyography, motor cortical stimulation).
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Objective To compare the pedaling force and lower extremity electromyography (EMG) with different cadences (60, 75, 90 r/min) and diverse cycling intensities (50%, 65%, 80% POV) and study the different influence on exerciser's pedaling force and lower extremity EMG. Methods Twelve healthy males participated in this study, and underwent two stages. In stage 1 the power output test at VO2max (POV) was got by cycle ergometer. In stage 2, nine conditions (3 kinds of intensities × 3 kinds of cadences) were completed respectively by using counter-balance design to record the changes for their pedaling force and lower extremity EMG. Results The negative pedaling work was significantly increased with the cadence increasing, and the appearing time of the peak pedaling force was significantly shifted forward in the cycle. When the crank angle was at 270°, the average increase of the pedaling force with the cadence increasing could obtain 1.84 times higher. In general, the firing rate of lower extremity muscular activation would be increased with the cadence increasing. Conclusions The cadence has greater effect on the pedaling force and lower extremity EMG. The tendency of pedaling force was shifted forward and the pattern of pedaling force became smoother with the cadence increasing. There are no significant differences among the diverse intensities. Based on the pedaling efficiency in this study, the optimal cadence for untrained people should be 60 r/min.
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Objective To observe the surface electromyography (sEMG) characteristics of upper limbs during one-finger pushing manipulation under different operating forces, so as to find out the muscle coordination movement pattern for key operating technology. Methods sEMG data of performing one-finger pushing manipulation by the expert, skilled and novice groups were collected. The manipulation force was divided into three different types, namely mild, moderate and severe. The continuous, stable data were adopted for analysis on Myo-Research software. Results Significant differences were found in the upper limb muscle integrated electromyography (iEMG) values (P0.05), with the flexor carpi ulnaris, deltoid, wrist flexors and extensors ranking the top three of iEMG ratio. The expert and skilled groups had the same core muscles in the same movement pattern during their manipulation operation, while the novice group had different core muscles under different forces. There were significant differences in co-contraction ratio among the expert, skilled and novice groups (P<0.01). The novice and expert groups had the highest and lowest co-contraction ratio, respectively, and the co-contraction ratio was gradually decreased with force increasing. During 6-minute manipulation operation, deltoid median frequency(MF) slope of the expert group was declined more slowly than that in the other two groups (P<0.05), which indicated that the expert group were better at resisting to fatigue. Conclusions The expert and skilled groups have the same sEMG characteristics during one-finger pushing manipulation operation with the same core muscles. The movement pattern of upper limb muscles is of regularity. The iEMG ratio, MF slope and co-contraction ratio can be used as reference standard for evaluating the durability, and homogeneity of the manipulation operation and normalization of force application.
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Objective To evaluate the recovery effect of postural control by electrical stimulation acupoint massage after local muscle fatigue by investigating joint torque, surface electromyography (EMG) signal, balance ability and foot pressure distributions. Methods Six subjects (12 person-times) accepted isokinetic, SEMG and foot pressure test under the condition of normal rest or electrical stimulation acupoint massage after ankle fatigue. Results After electrical stimulation acupoint massage, ①the forward and backward displacement of COF (center of force) was significantly reduced and the contact area of T1, T2 and T4,5 was increased to (11.64±2.12), (6.57±0.97), (3.72±1.33) cm2, respectively. ② In ankle isokinetic test (90°/s), the total work of ankle plantar flexion and dorsiflexion was significantly increased to (56.71±13.26) and (19.75±3.79) J. ③ In right leg stance, RMS (root mean square) of the tibialis anterior and lateral gastrocnemius was decreased significantly; the ankle isokinetic test (90°/s) showed that the RMS of the medial and lateral gastrocnemius was increased from (48.95±13.50) and (33.67±6.41) μV to (59.87±11.46) and (43.73±4.65) μV, respectively. Conclusions Electrical stimulation acupoint massage can optimize the force strategy and improve the stability of the ankle, further improve the postural control ability, promote the recovery of sports ability and avoid sports injuries.
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Objective To analyze how the athletes control postural balance through observing their joint angular motion change，center of pressure (COP) change and EMG activities of lower extremities for both athletes and beginners when performing the movement of white crane spreads its wings in Tai Chi Quan. Methods Twenty subjects were divided into 2 groups as 10 athletes and 10 beginners of Tai Chi Quan in each. When performing the movement of white crane spreads its wings, their EMG activities of 10 skeletal muscles, two-dimensional angular motion of 3 large joints in bilateral lower extremities, and COP displacements in lateral and anterior-posterior directions were recorded. Each performing trial took 8 seconds and repeated 5 times. All data were statistically processed for EMG, motion and balance analysis, and the EMG data were normalized to compare the differences between the athletes and beginners of Tai Chi Quan. Results The EMG activities of tibialis anterior(Ta), biceps femur(bF), gluteus medium(Gm) in support leg of athletes were significantly greater than those of the ipsilateral muscles in support leg of beginners, and the same was the EMG activities of gastrocnemius (G) and rectus femur（rF) in virtual leg of athletes compared with the beginners. The maximal average angular motion of 3 large joints and the coxa -joint motion of support leg in athletes were both significantly greater than that in beginners, but the anterior-posterior COP displacement in athletes was significantly smaller than that in beginners. Conclusions When performing the movement of white crane spreads its wings in Tai Chi Quan, athletes could oppose the COP change by enhancing muscle activities to maintain the postural balance, while beginners couldn’t make such active muscle activities against the uncontrolled anterior-posterior COP displacement. This may preliminarily explain the reason why Tai Chi Quan exercise can improve the muscle strength in lower extremities and enhance the ability of postural control.
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Objective To study the effect of passive motion from lower extremity on electromyography (EMG) activity of major muscles when the back under head down tilting state. Methods Thirty healthy subjects were selected. The EMGs of erector spinal and trapezius muscles were recorded and analyzed when human body was under head-down tilting at angel of 0°, 10°, 20° and 27° in static mode, respectively, in sway mode (along the axis of Z with frequencies of 120 and 140/min， respectively) and in vibration mode (along the axis of Y with frequency of 680/min) with the help of multifunctional test bed. Results In the static mode, the median frequency (MF) decreased with the increase of head-down titling angle; in the sway mode, the MF at each of 4 head-down tilting angles was smaller than that in the static mode. When the frequency was 120/min, the MF decreased with head-down tilting angle increasing, but when the frequency reached 140/min, the variation of MF became irregular. In the vibration mode, the MF increased with the increase of head-down tilting angle and was larger than that in the static mode. Conclusions In the static mode, the muscle fatigue increased with the head down tilting angle increasing; in the vibration mode, smaller head-down tilting angle should be selected to achieve better treatment effect; but in the sway mode, larger head-down tilting angle would be better, and the sway frequency should be set lower than 120/min to avoid potential damage due to excessive muscle fatigue.
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Objective To investigate the effect of a novel hip flexor training machine on muscle activation and range of motion (ROM) in lower limb under the condition of different resistances. Methods Six volunteers performed consecutive rightly hip flexion and extension for 30 times under light or heavy resistance randomly on the training machine, and the muscle activity and ROM in lower limb during the movement were measured at the same time. Results The muscle activation of rectus abdominal, hip flexor muscles, gluteus maximum, rectus femoris and biceps femoris under heavy resistance was significantly higher than that under light resistance (P<0.05); the muscle activation of rectus abdominis, hip flexor muscles and rectus femoris at during the last 3 times were significantly higher than that at of the first 3 times under heavy resistance (P<0.05); under light resistance, only the muscle activation of erector spinae and rectus femoris during the last 3 times were significantly higher than that of the first 3 times. The ROM and angle of hip extension under heavy resistance were significantly smaller than those under light resistance. Conclusions Under the rational ROM of hip joint, this new hip flexor training machine can stimulate the hip flexion and extension muscles and other co-contraction muscles to accomplish the movement, especially under the condition of heavy resistance.
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Objective To observe the electromyography (EMG) activities and kinematic characteristics of the back, abdomen and hip muscles under the static symmetric loading and unloading with the flexion and extension posture. Methods Six healthy male subjects stood on a specially designed testing platform, doing flexion/extension under symmetric loading and unloading, respectively. Each trial lasted 4 seconds and was repeated 3 times. The EMG activities of 10 muscles(rectus abdominis，obliquus externus abdominis，erector spinae，multifidus，gluteus Medius), the 3D angular movement, the plantar COP (center of pressure) were recorded during the trial.The normalized EMG, trunk angle and COP displacement were calculated, and statistical analyses of all data were made. Results Muscle activities of the back were greater (10.47~16.94) with flexion both under loading and unloading. Muscle activities of the abdomen were greater with extension under unloading, and those of the back (3.70~17.95) and hip (6.64~11.52) were increasing under loading, with muscle activities of the abdomen decreasing (10.66~4.18). The flashing trunk numbers was increased with the increase of loading, especially 1.55-time increase in the trunk angle. The COP displacement in anterior posterior direction was shifted greater than that in lateral direction, and this shift was more during flexion (14.60) than that during extension (7.65).Conclusions Extension increases the activities of back muscles, especially for multifidus, and it also increases the torso angular displacement and flashing trunk numbers, especially under loading.
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Objective To explore the influence of basketball shoes on impact force and corresponding muscle activation in the lower limb during the active and passive landing. Methods Twelve male ball players wearing two types of shoes (basketball shoes with cushioning insole vs. control shoes) performed the jump drop and passive landing from three different height on the tiltable platform. The dynamometric platform and electromyography (EMG) measurement system were used to collect the impact forces and EMG data from 5 major muscles in the lower limb simultaneously. Results As for the active drop jump, wearing basketball shoes didn’t have any effect on the amplitude/frequency of impact forces and muscle activation in the lower limb. However, during the passive landing, wearing basketball shoes could significantly decrease the amplitude of impact forces, the peak loading rate and the input frequency (P<0.05), and the post-activation of major muscles in the lower limb were also significantly decreased (P<0.05). Conclusions During the active landing, the intervention of footwear shows no significantly influence on characteristics of impact forces and muscle activation. However, when the human body does not under the full control of landing, wearing basketball shoes can change the input frequency, decrease the muscle post-activation, and play a positive role in preventing the sports injuries and enhancing the metabolic efficiency during the landing.
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Objective To illustrate the influences of walking speed and road slope on lower limb motions by quantitative analysis on the changes of joint angles and muscle activation. Method Five walking speeds and three road slopes were selected from slow to fast according to the related measurement. The gaits of 15 young women were measured using the motion capture system and the EMG signals of 8 major muscles in lower limbs were collected simultaneously. The mean joint angles of hip, knee and ankle in sagittal plane at different speeds and different slopes were calculated. The subject whose data was closest to the mean value could be easily found. Results The joint angles of the subject’s hip, knee and ankle in sagittal plane at different speeds and different slopes in a gait cycle were presented and the activation curves of the 8 major muscles during lower limb movements were obtained. Conclusions In each gait cycle, the curves of joint angles and muscle activations varied little with 5 different speeds, while curves for 3 different road slopes only showed similar tendencies but with different peaks.
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Objective To provide theoretical reference for the research on lateral postural control in older people by using the electromyography （EMG）technique to compare the neuromuscular reaction between the young and older people during lateral perturbation. Methods Postural reactions of 14 young people and 14 older people as subjects were evoked by sudden unpredictable medio lateral translation platform. The surface EMG data were collected from peroneus longus, anterior tibialis, gluteus medius and erector spinae of the left side of the body. Results The latencies in anterior tibialis, gluteus medius and erector spinae were obviously delayed in older people, and the duration of time to peak in peroneus longus, anterior tibialis and gluteus medius of older people was much longer than that of young people. Conclusions The delayed response of ankle, hip and trunk muscle and the low efficacy of contraction rate in ankle and hip muscles to the unexpected perturbation might be the primary reason for the decrease of lateral postural control in older people.
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Objective To investigate the acute effect of local vibration stimulus with low frequency on hand control ability, flexibility, grip strength, and muscle EMG activity. Methods 10 subjects in this study held a vibrator for 20 seconds with isometric contraction at the vibration frequency of 12.5 Hz (vibration group, VIB) or with only isometric contraction (control group, CON). The same procedure measurement, including control ability, flexibility, grip strength, and muscle activity, were recorded both at pre-stimulus (pre-test) and 60-second after stimulus (post-test), respectively. Paired-t test was used to compare the values between pre-test and post-test and the changing rate between groups. Results The control ability and flexibility in pre-post test showed significant improvement after VIB intervention in VIB (P＜0.05). The changing rate of grip strength and EMG in VIB was significantly higher than those in CON (P＜0.05). Conclusions Acute local vibration stimulus with low frequency can be used to improve the hand control ability and flexibility for those who need better hand functional ability in the future.
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Objective To study the effect of reasonable jogging speed on body shape and walking gait to make people acquire graceful posture through jogging. Method Five jogging speeds were selected according to related measurements. Kinematical data of subjects (15 young women volunteers) in jogging were measured by the motion capture system, while the EMG signals of 8 major muscles in lower limb were collected simultaneously. The mean angles of hip, knee and ankle joints in sagittal plane at different speeds were calculated. The subject whose data was closest to the mean value was chosen as the research subject and analyze the kinematical data. Results The angles of the subject's hip, knee and ankle joints in sagittal plane at different speeds in a gait cycle were presented, and activation curves of her 8 major muscles were obtained during lower limb movements. Relationships between the jogging speed, jogging stage, muscle activation and joint angle were described by the scoring method. Conclusions The range of joint angle and maximum of muscle activation don't change with jogging speed monotonously. The study provides a reference for young women to choose their own jogging speed.
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Os pontos gatilhos miofasciais (PGMs) são manifestações comumente encontradas na prática clínica e estão relacionados à alteração de tônus e à síndrome dolorosa miofascial (SDM). OBJETIVO: Avaliar a capacidade da EMG de superfície e detectar alterações da atividade neuromuscular no PGM, em situações de repouso e de contração isométrica voluntária máxima. MÉTODO: Participaram do estudo 56 indivíduos distribuídos em dois grupos: grupo Saudável com 28 indivíduos, que necessariamente não possuíam PGM, e o grupo Dor, constituído de 28 indivíduos que possuíam necessariamente PGM no músculo escolhido. O grupo Dor apresentava indivíduos com PGM latente e ativo, e com e sem fenômenos autonômicos (FA). RESULTADOS: O sinal EMG da porção muscular com PGM mostrou-se significativamente maior quando comparado com a porção muscular sadia do grupo Dor, e do grupo Saudável durante o repouso (26,56 ± 44,54, 5,39 ± 6,29 e 1,56 ± 0,76, respectivamente, p = 0,0001). Os indivíduos com PGM ativo obtiveram maior intensidade do sinal EMG do que aqueles que apresentaram PGM latente (17,85 ± 30,25 versus 3,74 ± 1,52, p = 0,04). Além disso, os indivíduos que apresentaram fenômenos autonômicos tiveram maior intensidade do sinal EMG do que aqueles que não os apresentaram (16,78 ± 28,44 versus 3,51 ± 3,65), na condição de repouso. CONLUSÃO: A EMG de superfície é capaz de mensurar a atividade do PGM, principalmente na condição de repouso.
There are examples of common clinical conditions that clinical signals are related to alterations in muscle tone, including myofascial pain syndrome. OBJECTIVE: to discuss the application of surface EMG to detect effect of miofascial trigger point (MTP) on neuromuscular activity at rest and maximum voluntary contraction of the trapezoid muscle. METHODS: Fifty-six subjects participated in the study and were divided into two groups: Healthy group (n = 28), with subjects who necessarily did not present MTP, and PAIN group (n = 28), with subjects who necessarily had MTP. RESULTS: The EMG signal was significantly higher in the muscle portion containing MTP than in the healthy muscle portion in PAIN group and than Healthy group (26,56 ± 44,54, 5,39 ± 6,29 and 1,56 ± 0,76, respectively, p = 0,0001) during rest. In addition, a higher intensity of the EMG signal was observed in subjects with active MTP than in latent MTP (17,85 ± 30,25 versus 3,74 ± 1,52, p = 0,04. Besides, the subjects who presented autonomic phenomena had higher EMG signal than those who had no autonomic phenomena (16,78 ± 28,44 versus 3,51 ± 3,65. CONCLUSION: The surface EMG is reliable to measure the muscular activity of the MTP, mainly at rest condition.
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Humans , Male , Female , Electromyography , Muscle Tonus , Myofascial Pain SyndromesABSTRACT
BACKGROUND AND PURPOSE: For the diagnosis of amyotrophic lateral sclerosis(ALS), symptoms and signs of upper motor neuron(UMN) and lower motor neuron(LMN) involvement should be confirmed. The electromyography(EMG) studies are known to be essential for the demonstration of LMN involvement. The authors assessed the value of the EMG in the diagnosis of ALS. METHODS: The authors collected 51 patients (M:F=31:20, age:51.9?12.0 years) who were diagnosed and followed up at Seoul National University Hospital from 1994 to 1996. Diagnosis of ALS was based on the El Escorial diagnostic criteria. They were classified to be definite in 5, probable in 23, and possible in 23. On view of the affected area of onset, they consisted of 12 bulbar and 39 spinal form of ALS. The needle EMG studies were performed in limb, thoracic paraspinal and tongue muscles. RESULTS: Of 51 cases, it was possible to demonstrate widespread denervations at the initial needle EMG tests in 46(90.2%); 5 of 5 definite, 21 of 23 probable, and 20 of 23 possible ALS. Among 30 spinal form ALS without bulbar symptoms, the initial EMG evaluation showed the widespread denervation processes in three limbs in 13(43.3%) and in two limbs in 17(56.7%). Of 17 patients with denervation in only two limbs, the thoracic paraspinal and tongue muscles were found to be involved in 7 and 5 cases, respectively. The other 5, who initially showed abnormal EMG in limited muscles without abnormal EMG finding in thoracic paraspinal and tongue muscles, were confirmed to have ALS by the clinical and EMG follow-up. Nine patients of spinal onset ALS with bulbar symptoms and 12 patients of bulbar onset showed widespread denervation features at the tongue and limb muscles. In 6 ALS cases, difficult to be differentiated from spondylotic myeloradiculopathy, the abnormal EMG features in thoracic paraspinal and bulbar muscle were helpful to diagnose ALS. CONCLUSION: The authors could diagnose ALS in most cases(90.2%) at the time of initial EMG evaluation. The needle EMG study with the regular follow-up is useful to diagnose ALS. Moreover, the needle EMG study on thoracic paraspinal and tongue muscle is much helpful to differentiate ALS from spondylotic myeloradiculpathy.