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1.
In the last three decades it has become quite common to evaluate local muscle fatigue by means of surface electromyographic (sEMG) signal processing. A large number of studies have been performed yielding signal-based quantitative criteria of fatigue in primarily static but also in dynamic tasks. The non-invasive nature of this approach has been particularly appealing in areas like ergonomics and occupational biomechanics, to name just the most prominent ones. However, a correct appreciation of the findings concerned can only be obtained by judging both the scientific value and practical utility of methods while appreciating the corresponding advantages and limitations. The aim of this paper is to serve as a state of the art summary of this issue. The paper gives an overview of classical and modern signal processing methods and techniques from the standpoint of applicability to sEMG signals in fatigue-inducing situations relevant to the broad field of biomechanics. Time domain, frequency domain, time–frequency and time-scale representations, and other methods such as fractal analysis and recurrence quantification analysis are described succinctly and are illustrated with their biomechanical applications, research or clinical alike. Examples from the authors’ own work are incorporated where appropriate. The future of this methodology is projected by estimating those methods that have the greatest chance to be routinely used as reliable muscle fatigue measures.  相似文献   

2.
Myotonometric measurement of muscle compliance represents new technology that quantifies muscle tone. Compliance change during muscle contraction might provide an indirect measure of strength. The purpose of this study was to determine relationships among myotonometric measurements of muscle compliance, surface electromyographic (sEMG) measurements of muscle activation and joint force production during voluntary isometric knee extensions. The level of relationship will contribute to the construct validity of use of muscle compliance as an indirect strength measurement. Thirteen male subjects, mean age 25 +/- 1.5 years, participated. Simultaneous recordings of myotonometric, sEMG of the rectus femoris and isometric knee extension force measurements were taken at rest, during maximal voluntary contraction (MVC), and during 33% and 66% MVC contractions. Relationships among the three measurement procedures were calculated using correlation and regression analyses. Myotonometric measures of muscle compliance, sEMG and force measurements were highly correlated. Myotonometric measurements were best represented by a curvilinear (quadratic) relationship to sEMG (r = 0.82, p < 0.001) and joint force (r = 0.83, p < 0.001). The present experiments establish the construct validity of myotonometric measurements of muscle compliance as an indirect means of quantifying muscle strength and activation levels. This method, therefore, offers a possible alternative for cases in which direct measurement of joint force or sEMG is difficult or inappropriate.  相似文献   

3.
目的:以腕-肘关节为例,探讨不同水平运动负荷诱发尺侧腕屈肌(FCU)和肱二头肌(BB)疲劳过程中sEMG信号与各关节最大屈肌肌力的关系。方法:采集10名青年男性受试者在不同负荷水平(30%、55%、80%MVC)下疲劳过程中尺侧腕屈肌(FCU)和肱二头肌(BB)的表面肌电信号和各关节在疲劳前后的MVC。结果:不同运动负荷强度分别诱发前臂和上臂肌肉疲劳过程中,腕、肘关节最大屈肌肌力明显下降且具有明显负荷强度效应:BB和FCU的MPF与MF单调递减且下降率具有明显的负荷强度效应;不同负荷强度下BB和FCU的MPF和MF下降斜率与肘、腕关节最大屈肌肌力的下降比值之间有明显相关。结论:局部肌肉疲劳过程中MPF和MF下降率变化能够对相应关节最大肌力变化作出比较准确预测。  相似文献   

4.
OBJECTIVE: The objective of this study was to determine whether mechanical force, manually-assisted (MFMA) spinal manipulative therapy (SMT) affects paraspinal muscle strength as assessed through use of surface electromyography (sEMG). DESIGN: Prospective clinical trial comparing sEMG output in 1 active treatment group and 2 control groups. SETTING: Outpatient chiropractic clinic, Phoenix, AZ. SUBJECTS: Forty subjects with low back pain (LBP) participated in the study. Twenty patients with LBP (9 females and 11 males with a mean age of 35 years and 51 years, respectively) and 20 age- and sex-matched sham-SMT/control LBP subjects (10 females and 10 males with a mean age of 40 years and 52 years, respectively) were assessed. METHODS: Twenty consecutive patients with LBP (SMT treatment group) performed maximum voluntary contraction (MVC) isometric trunk extensions while lying prone on a treatment table. Surface, linear-enveloped sEMG was recorded from the erector spinae musculature at L3 and L5 during a trunk extension procedure. Patients were then assessed through use of the Activator Methods Chiropractic Technique protocol, during which time they were treated through use of MFMA SMT. The MFMA SMT treatment was followed by a dynamic stiffness and algometry assessment, after which a second or post-MVC isometric trunk extension and sEMG assessment were performed. Another 20 consecutive subjects with LBP were assigned to one of two other groups, a sham-SMT group and a control group. The sham-SMT group underwent the same experimental protocol with the exception that the subjects received a sham-MFMA SMT and dynamic stiffness assessment. The control group subjects received no SMT treatment, stiffness assessment, or algometry assessment intervention. Within-group analysis of MVC sEMG output (pre-SMT vs post-SMT sEMG output) and across-group analysis of MVC sEMG output ratio (post-SMT sEMG/pre-SMT sEMG output) during MVC was performed through use of a paired observations t test (POTT) and a robust analysis of variance (RANOVA), respectively. MAIN OUTCOME MEASURES: Surface, linear-enveloped EMG recordings during isometric MVC trunk extension were used as the primary outcome measure. RESULTS: Nineteen of the 20 patients in the SMT treatment group showed a positive increase in sEMG output during MVC (range, -9.7% to 66.8%) after the active MFMA SMT treatment and stiffness assessment. The SMT treatment group showed a significant (POTT, P < 0.001) increase in erector spinae muscle sEMG output (21% increase in comparison with pre-SMT levels) during MVC isometric trunk extension trials. There were no significant changes in pre-SMT vs post-SMT MVC sEMG output for the sham-SMT (5.8% increase) and control (3.9% increase) groups. Moreover, the sEMG output ratio of the SMT treatment group was significantly greater (robust analysis of variance, P = 0.05) than either that of the sham-SMT group or that of the control group. CONCLUSIONS: The results of this preliminary clinical trial demonstrated that MFMA SMT results in a significant increase in sEMG erector spinae isometric MVC muscle output. These findings indicate that altered muscle function may be a potential short-term therapeutic effect of MFMA SMT, and they form a basis for a randomized, controlled clinical trial to further investigate acute and long-term changes in low back function.  相似文献   

5.
The use of brightness-mode ultrasound and Doppler ultrasound in physical medicine and rehabilitation has increased dramatically. The continuing evolution of ultrasound technology has also produced ultrasound elastography, a cutting-edge technology that can directly measure the mechanical properties of tissue, including muscle stiffness. Its real-time and direct measurements of muscle stiffness can aid the diagnosis and rehabilitation of acute musculoskeletal injuries and chronic myofascial pain. It can also help monitor outcomes of interventions affecting muscle in neuromuscular and musculoskeletal diseases, and it can better inform the functional prognosis. This technology has implications for even broader use of ultrasound in physical medicine and rehabilitation practice, but more knowledge about its uses and limitations is essential to its appropriate clinical implementation. In this review, we describe different ultrasound elastography techniques for studying muscle stiffness, including strain elastography, acoustic radiation force impulse imaging, and shear-wave elastography. We discuss the basic principles of these techniques, including the strengths and limitations of their measurement capabilities. We review the current muscle research, discuss physiatric clinical applications of these techniques, and note directions for future research.  相似文献   

6.
目的:观察肌电生物反馈疗法联合康复训练对脊髓损伤(SCI)患者运动功能障碍的康复疗效。方法:60例胸腰段不完全性脊髓损伤患者随机分为观察组和对照组,每组30例。2组均进行常规康复治疗,观察组加用双下肢肌电生物反馈治疗。治疗前及治疗后8周、12周进行下肢肌肉最大收缩时表面肌电(sEMG)信号采集、运动功能评定及功能独立性(FIM)评定,比较临床疗效。结果:治疗8周后,2组患者股四头肌、胫前肌最大收缩时的sEMG信号均较治疗前明显提高(P0.05),治疗后12周继续提高(P0.01);观察组sEMG信号增幅高于对照组(P0.05)。治疗8周后,2组患者ASIA运动功能评分及FIM评分亦较治疗前提高(P0.05),组间比较差异无统计学意义;治疗12周后,2组ASIA运动功能及FIM评分较治疗8周后提高更明显(P0.01),观察组更高于对照组(P0.05)。结论:肌电生物反馈疗法联合康复训练对胸腰段不完全性脊髓损伤患者运动功能有促进作用,能明显提高患者的股四头肌、胫前肌表面肌电信号及肌力,并能提高功能独立水平,减少并发症。  相似文献   

7.
Wang K  Svensson P  Arendt-Nielsen L 《Pain》2000,88(2):189-197
The modulation of human jaw-stretch reflexes by experimental muscle pain was studied in three experiments. Short-latency reflex responses were evoked in the masseter and temporalis muscles by fast stretches (1 mm displacement, 10 ms ramp time) before, during and 15 min after a period with tonic pain. In Expt. I, a dose of 5.8% hypertonic or 0.9% isotonic (control) saline was infused in random order into the left masseter for up to 15 min (n=12). The level of excitation of the left masseter was kept constant at 15% of maximal effort by visual feedback and on-line calculation of the root-mean-square value of the surface electromyogram (sEMG). In Expt. II, a dose of 5.8% saline was infused into the left masseter but with feedback from the right masseter sEMG (n=12). In Expt. III, both sEMG and intramuscular (im) EMG was recorded from the left and right masseter muscles. The feedback was from either the sEMG or imEMG of the left masseter in which 5.8% saline was infused (n=12). In all experiments, subjects continuously rated their perceived pain intensity on a 10-cm visual analogue scale (VAS). Infusion of 5.8% saline caused moderate levels of pain (mean VAS 4.9-5.0 cm) whereas infusion of 0.9% saline was almost pain-free (mean VAS 0.3 cm). The pre-stimulus EMG activity in the masseter, which served as the feedback muscle during the recording, was constant across the different conditions. During painful infusion of 5.8% saline in Expts. I and III, the pre-stimulus sEMG activity in the non-painful masseter was significantly higher than baseline when the sEMG on the painful side was used as feedback signal, and in Expt. II significantly lower on the painful side when the non-painful side served as feedback signal (Student-Newman-Keuls: P<0.05). Isotonic saline did not affect the pre-stimulus sEMG activity or the jaw-stretch reflex parameters. The peak-to-peak amplitude of the stretch reflex in the painful masseter normalized to the pre-stimulus EMG activity was significantly higher during the pain conditions compared with the pre- and post-infusion conditions in all experiments. These results indicate that experimental jaw-muscle pain facilitates the short-latency (8-9 ms), probably monosynaptic, jaw-stretch reflex as revealed by both sEMG and imEMG. This effect could not be accounted for by variability in pre-stimulus EMG activity. An increased sensitivity of the fusimotor system at this level of static muscle excitation is suggested as a possible mechanism, which could contribute to an increased stiffness of the jaw-muscles during pain.  相似文献   

8.
BACKGROUND AND PURPOSE: Scapular muscle performance evaluated with a handheld dynamometer (HHD) has been investigated only in people without shoulder dysfunction for test-retest reliability of data obtained with a single scapular muscle test. The purpose of this study was to assess the reliability, error, and validity of data obtained with an HHD for 4 scapular muscle tests in subjects with shoulder pain and functional loss. SUBJECTS AND METHODS: Subjects (N=40) with shoulder pain and functional loss were tested by measuring the kilograms applied with an HHD during 3 trials for muscle tests for the lower trapezius, upper trapezius, middle trapezius, and serratus anterior muscles. Concurrently, surface electromyography (sEMG) data were collected for the 4 muscles. The same procedures were performed 24 to 72 hours after the initial testing by the same tester. Muscle tests were performed 3 times, and the results were averaged for data analysis. RESULTS: Intraclass correlation coefficients for intratester reliability of measurements of isometric force obtained using an HHD ranged from .89 to .96. The standard error of the measure (90% confidence interval [CI]) ranged from 1.3 to 2.7 kg; the minimal detectable change (90% CI) ranged from 1.8 to 3.6 kg. Construct validity assessment, done by comparing the amounts of isometric muscle activity (sEMG) for each muscle across the 4 muscle tests, revealed that the muscle activity of the upper trapezius and lower trapezius muscles was highest during their respective tests. Conversely, the isometric muscle activity of the middle trapezius and serratus anterior muscles was not highest during their respective tests. DISCUSSION AND CONCLUSION: In people with shoulder pain and functional loss, the intrarater reliability and error over 1 to 3 days were established using an HHD for measurement of isometric force for the assessment of scapular muscle performance. Error values can be used to make decisions regarding individual patients. Construct validity was established for the lower and upper trapezius muscle tests; therefore, these tests are advocated for use. However, construct validity was not demonstrated for the serratus anterior and middle trapezius muscle tests as performed in this study. Further investigation of these muscle tests is warranted.  相似文献   

9.
BACKGROUND: In the comprehensive assessment of painful conditions, dynamic surface electromyography (sEMG) and range of motion (ROM) recordings can provide information regarding muscle spasm, antalgic postures, fear of pain (protective guarding), muscle injury, and disordered movement caused by pain. This study examines ROM and sEMG patterns observed during cervical flexion. OBJECTIVE: To demonstrate 2 distinctive sEMG recruitment and dynamic ROM patterns observed during cervical flexion and return to mid-line. DESIGN: Single-subject design with independent measurement of dynamic ROM and sEMG. SETTING: Applied clinical setting. PARTICIPANTS: Two subjects with normal ROM and cervical muscles were studied. MAIN OUTCOME MEASURE: One subject was studied with sEMG. looking at the cervical paraspinals and sternocleidomastoid muscles; the other subject was studied with an active ROM device. Three cervical movements were studied: lower cervical flexion, atlantoaxial (upper) cervical flexion, and a combination upper/lower cervical flexion. RESULTS: The active ROM device indicates larger movements (higher degrees of flexion) for the lower cervical flexion compared with upper flexion. The combined movement indicates a differential movement from 2 spinal segments. The sEMG recordings indicated differential recruitment patterns. The sternocleidomastoid recruits briskly during the flexion phase of the upper cervical flexion movement, whereas the cervical paraspinals recruit briskly during return to mid-line when the lower cervical flexion is used. The combined upper then lower cervical flexion movement recruits both sets of muscles. CONCLUSIONS: The results of the study indicate 2 distinct movement patterns associated with upper versus lower cervical flexion and 2 distinct sEMG recruitment patterns. The study suggests that these 2 distinct movements involve 2 distinct cervical segments and are associated with recruitment of different muscle groups. Applied clinical research on the cervical spine should use sEMG recordings to assess both the upper and lower flexion movements as the standard for the study of cervical flexion.  相似文献   

10.
This study of measures of spasticity, or altered motor control, compares the clinically used Ashworth scale with a method based on surface electromyographic (sEMG) recordings called brain motor control assessment (BMCA) in a group of 97 subjects with spinal cord injury (SCI) and varying levels of motor dysfunction. In this paper, we describe how sEMG-derived scores relate to the severity of spasticity as judged clinically. When sEMG data from passive movements from the BMCA were analyzed by Ashworth category, we found that when the sEMG data were averaged for a limb, there was a significant difference between scores for those with Ashworth 0 vs. 2 and 3, and 1 vs. 2 and 3 (p<0.001), but not between 0 and 1. Analysis of the individual muscle scores improved the discrimination between Ashworth categories. Superiority of sEMG data over Ashworth category as an objective quantification of altered motor control ("spasticity") is argued.  相似文献   

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