Using surface electromyography to study cervical extensor muscle activity: an investigation of methodological considerations and the effects of age on fatigue … (original) (raw)
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Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2002
This research had two purposes: to identify measures sensitive to fatigue development associated with low force, static exertions and to investigate the effects of aging on fatigue onset associated with low-level exertions of the neck musculature. Fourteen subjects participated ranging in age from 20 to 62 years. The task consisted of a submaximal neck extension exertion held until fatigue. Based on the results of this experiment, it was found that: ▪ Several measures are sensitive to fatigue induced during a low-level static exertion of the neck extensor muscles, including: discomfort, three EMG time domain and four frequency domain parameters ▪ when comparing groups based on age, results and interpretations of effects due to age may be directly be influenced by the choice of dependent measure (such as discomfort, maximum force, and potentially time to fatigue); ▪ regardless of age, some subjects may exhibit fatigue resistance at low exertions levels.
Low-level exertions of the neck musculature: A study of research methods
Journal of Electromyography and Kinesiology, 2006
Musculoskeletal neck discomfort is prevalent in many occupations and has been the focus of much research employing surface electromyography (sEMG). Significant differences in experimental methods among researchers make comparisons across studies difficult. The goal of the current research was to use empirical methods to answer specific methodological questions concerning use of sEMG in evaluation of the neck extensor system. This was accomplished in two studies. In Experiment 1, ultrasound technology was used to: (a) determine accessibility of m. splenius and semispinalis capitis with surface electrodes, (b) identify appropriate electrode locations for these muscles/muscle groups, and (c) illustrate potential benefits of using ultrasound in locating muscles/placing electrodes. Experiment 2 sought to assess effects of posture when normalizing sEMG data. Results from Experiment 1 showed no direct access to semispinalis capitis for surface electrodes; their activity can only be sampled as part of a group of muscles. In most subjects, m. splenius was found to be accessible to surface electrodes. Electrode placement recommendations are provided. Results of Experiment 2 showed significant differences in normalized EMG data between a posture-specific technique and a reference posture technique. Posture-specific normalization is recommended for accurately assessing the relative intensity of contractions of these muscles.
Use of surface electromyography to estimate neck muscle activity
Journal of Electromyography and Kinesiology, 2000
This paper reviews the literature concerning the use of surface electromyography (sEMG) for the study of the neck musculature in response to work and workplace design during light work and semi-static tasks. The paper also draws upon basic research and biomechanical modeling in order to provide methodological recommendations for the use of surface electromyography in this region of the body and to identify areas which require further investigation. The paper includes review and discussion of electrode site location, methods of normalization, data reliability, and factors that can affect sEMG signals from this region, including noise, physiologic artifact, stress, visual deficiencies, and pain. General guidance for maximum exertions with the neck musculature, for sEMG normalization or other purposes, is also included.
Cervical flexion–relaxation response to neck muscle fatigue in males and females
Journal of Electromyography and Kinesiology, 2014
In this study the effect of muscle fatigue on the cervical spine flexion-relaxation response was studied. Twenty healthy participants (10 males and 10 females) were recruited for data collection. The Sorenson protocol was utilized to induce neck muscle fatigue. Surface electromyography and optical motion capture systems were used to measure neck muscle activation and head-neck posture, respectively. A post-fatigue reduction in the Flexion-Relaxation Ratio (FRR) and higher FRR for females compared to males were observed. A post-fatigue decrease was also observed in the onset and offset angles resulting in an expansion of the myoelectric silence period. Gender had no effect on the onset and offset angles of the silence period. Post-fatigue shift in the onset and offset angles and the expansion of the silence period indicate an increased contribution by the passive viscoelastic tissues in stabilizing the cervical spine under fatigued condition.
… : official journal of the …, 2005
The repeatability of subjective and objective assessments of neck muscle fatigue is very important with regard to the clinical applicability of these methods.To establish between-days reliability, 33 healthy volunteers performed a 60% maximum voluntary isometric contraction test from a standing position in all neck movements. Cervical muscle fatigue was assessed on three separate occasions from the spectral (median frequency, MF) and amplitude (root mean square, RMS) analysis of the electromyogram (EMG) signal recorded from the cervical paraspinal group, splenius capitis, levator scapulae and sternocleidomastoid. Subjective assessment of fatigue was rated by employing the Borg scale. Intraclass correlation coefficient ICC(1,1), standard error of measurement (SEM), smallest detectable difference (SDD) indices and Pearson’s correlation co-efficient were calculated for the analysis of the results.Normalised median frequency (MF) slope had low repeatability and large between-day error (ICC(1,1) = 0.28–0.61; SEM = 0.33–0.60%/s; SDD = 132.7–703.2%) for the protagonist muscles of each movement. Initial median frequency (IMF) had moderate to good reliability and small error (ICC(1,1) = 0.64–0.81; SEM = 2.8–8.8 Hz; SDD = 19.9–38.5%). The RMS slope yielded also poor repeatability. The Borg assessment was more reliable than the EMG estimate though variability between sessions was still quite high (SDD = 29.2–136.5%). No correlation was found between the EMG and Borg assessment of neck muscle fatigue (r = −0.01–0.39).The protocol used for assessing neck muscle fatigue proved to be reliable only for the IMF but the clinical usefulness of this measure remains questionable. The lack of correlation between objective and subjective estimation of neck muscle fatigue was possibly a consequence of the poor measurement repeatability. Further research is needed to identify the factors responsible for these results on neck area.
Iranian Rehabilitation Journal , 2021
This study presents a method of assessing muscle fatigue during endurance testing at 50% maximal voluntary contraction (MVC) using electromyography (EMG) information as indirect indices of fatigability in the forearm muscles, namely, flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi ulnaris (ECU) and extensor carpi radialis brevis (ECRB)." This study presents a method of assessing muscle fatigue during endurance testing at 50% maximal voluntary contraction (MVC) using electromyography (EMG) information as indirect indices of fatigability in the forearm muscles, namely, flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi ulnaris (ECU) and extensor carpi radialis brevis (ECRB). Methods: A randomized comparative experimental design was used during endurance test with 8 VT protocols; based on different combinations of vibration frequency (35 & 45 Hz), amplitude (3±0.5g & 9±0.5g), and exposure duration (30 & 60 seconds), i.e., were given to the study participants for 4 days. A random sampling of participants was conducted from two groups (n=56/group), as follows: individuals with a Sedentary Lifestyle (SL) and a group of Construction Workers (CW). Results: Multivariate Analysis of Variance (MANOVA) results indicated a significant increase in EMG rms, median frequency, waveform length, mean absolute value (P<0.001), and the variance of EMG signal (P<0.05) (except in ECU for the SL group and ECRB for the CW group on the variance of EMG signal) after VT in all muscles of both research groups. Therefore, an increase in the EMG parameter value after a grip endurance task revealing an elevation in EMG signal amplitude is indicative of muscle fiber fatigue. Furthermore, the strongest correlation was found between grip endurance and WL (r=0.471, P<0.001), and EMG rms (r=0.401, P<0.001) of the ECU muscle in the SL group only. Discussion: The patterns of EMG signal represented the amplitude and spectral parameters of the signal, enabling real-time fatigue analysis. Additionally, surface EMG information is useful for indirectly evaluating performance fatigue during the endurance test.
Assessment of low back muscle fatigue by surface EMG signal analysis: methodological aspects
Journal of Electromyography and Kinesiology, 2003
This paper focuses on methodological issues related to surface electromyographic (EMG) signal detection from the low back muscles. In particular, we analysed (1) the characteristics (in terms of propagating components) of the signals detected from these muscles; (2) the effect of electrode location on the variables extracted from surface EMG; (3) the effect of the inter-electrode distance (IED) on the same variables; (4) the possibility of assessing fatigue during high and very low force level contractions. To address these issues, we detected single differential surface EMG signals by arrays of eight electrodes from six locations on the two sides of the spine, at the levels of the first (L1), the second (L2), and the fifth (L5) lumbar vertebra. In total, 42 surface EMG channels were acquired at the same time during both high and low force, short and long duration contractions. The main results were: (1) signal quality is poor with predominance of non-travelling components; (2) as a consequence of point (1), in the majority of the cases it is not possible to reliably estimate muscle fiber conduction velocity; (3) despite the poor signal quality, it was possible to distinguish the fatigue properties of the investigated muscles and the fatigability at different contraction levels; (4) IED affects the sensitivity of surface EMG variables to electrode location and large IEDs are suggested when spectral and amplitude analysis is performed; (5) the sensitivity of surface EMG variables to changes in electrode location is on average larger than for other muscles with less complex architecture; (6) IED influences amplitude initial values and slopes, and spectral variable initial values; (7) normalized slopes for both amplitude and spectral variables are not affected by IED and, thus, are suggested for fatigue analysis at different postures or during movement, when IED may change in different conditions (in case of separated electrodes); (8) the surface EMG technique at the global level of amplitude and spectral analysis cannot be used to characterize fatigue properties of low back muscles during very low level, long duration contractions since in these cases the non-stable MU pool has a major influence on the EMG variables. These considerations clarify issues only partially investigated in past studies. The limitations indicated above are important and should be carefully discussed when presenting surface EMG results as a means for low back muscle assessment in clinical practice.
PLOS ONE, 2015
The aim of this study is to determine if the fatigue of cervical muscles has a significant influence on the head-neck segment musculo-tendinous stiffness. Methods Ten men (aged 21.2 ± 1.9 years) performed four quick-release trials of flexion at 30 and 50% MVC before and after the induction of muscular fatigue on cervical flexors. Electromyographic activity was recorded on the sternocleidomastoids (SCM) and spinal erectors (SE), bilaterally. Musculo-tendinous stiffness was calculated through the quick-release method adapted to the head-neck segment. Results We noticed a significant linear increase of the head-neck segment musculo-tendinous stiffness with the increase of exertion level both before (P < 0.0001) and after the fatigue procedure (P < 0.0001). However, this linear relationship was not different before and after the fatigue procedure. EMG analysis revealed a significant increase of the root mean square for the right SCM
Surface EMG based muscle fatigue evaluation in biomechanics
Clinical Biomechanics, 2009
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.