Erector Spinae Muscle Fatigue Research Articles

Effects of a Passive Back-Support Exosuit on Postural Control and Cognitive Performance During a Fatigue-Inducing Posture Maintenance Task.

To evaluate the effectiveness of passive back-support exosuit on postural control and cognitive performance during a fatigue-inducing posture maintenance task. Wearable support systems (exoskeletons/exosuits) reduce physical demands but may also influence postural control and cognitive performance by reducing muscular fatigue. Eighteen participants visited on two different days to test an exosuit system and performed dual-task cognitive assessments based on human information processing (information acquisition, information integration, and action implementation) while maintaining a 35° trunk flexion posture for 16minutes. Center-of-pressure (CoP), cognitive performance, and perceived workload were recorded, while erector spinae muscle activity was captured to quantify muscle fatigue. The exosuit was effective in reducing erector spinae muscle fatigue during the static posture maintenance task (61% less in Δmedian frequency: -9.5Hz (EXO-Off) versus -3.7Hz (EXO-On)). The fatigue-inducing task increased CoP velocity as a function of time (29% greater: 9.3mm/sec (pre) versus 12.0mm/sec (post)), and exosuit use decreased CoP velocity (23% less: 12.1mm/sec (EXO-Off) versus 9.4mm/sec (EXO-On)). The exosuit was also effective at mitigating cognitive degradation, as evidenced by a higher hit-to-signal ratio (8% greater: 81.3 (EXO-Off) versus 87.9 (EXO-On)) in the information integration task and reducing perceived workload in all stages of human information processing. Exosuit provided benefits of postural control and information integration processing during a 16-min static posture maintenance task. Torso exoskeletons/suits can have positive implications for occupations with concurrent physical and cognitive demands.

Quantifying the effectiveness of a passive trunk-support exosuit at reducing erector spinae muscle fatigue during a quasi-static posture maintenance task

The objective of this study was to explore the effectiveness of a passive back-support exosuit at reducing low back muscle fatigue during an 18-minute trunk posture maintenance task. On two separate days sixteen participants performed an 18-minute trunk posture profile that reflected trunk flexion postures observed during a challenging vascular surgery procedure. On one day they performed the procedure with the support of the exosuit, on the other day without. Test contractions were performed every three minutes to capture the time-dependent electromyographic activity of the bilateral erector spinae muscles. Time domain (amplitude) and frequency domain (median frequency) measures of erector spinae muscle fatigue were assessed. Results revealed that the exosuit significantly reduced the measures of erector spinae muscle fatigue in terms of both amplitude (6.1%) and median frequency (5.3%), demonstrating a fatigue reduction benefit of the exosuit in a realistic surgical posture maintenance task.

Impact of a passive upper-body exoskeleton on muscle activity, heart rate and discomfort during a carrying task.

The goal of this study was to compare erector spinae muscle fatigue, upper limb muscle activity, body areas discomfort, and heart rate during a 10-min carrying task with and without a passive upper-body exoskeleton (CarrySuitⓇ) while considering sex influences. Passive exoskeletons are commercially available to assist lifting or carrying task. However, evidence of their impact on muscle activity, fatigue, heart rate and discomfort are scarce and/or do not concur during carrying tasks. Thirty participants (16 females and 14 male) performed a 10-min, 15kg load-carrying task with and without the exoskeleton in two non-consecutive days. Heart rate, and erector spinae, deltoid, biceps and brachioradialis muscle activity were recorded during the carrying tasks. In addition, erector spinae electromyography during an isometric hold test and discomfort ratings were measured before and after the task. While without the exoskeleton upper limb muscle activity increased or remained constant during the carrying task and showing high peak activation for both males and females, a significant activity reduction was observed with the exoskeleton. Low back peak activation, heart rate and discomfort were lower with than without the exoskeleton. In males muscle activation was significantly asymmetric without the exoskeleton and more symmetric with the exoskeleton. The tested passive exoskeleton appears to alleviate the physical workload and impact of carrying heavy loads on the upper limbs and lower back for both males and females.

The Effect of Erector Spinae Muscle Fatigue on the Sensation of Trunk, Hip, and Knee Position among the Male Karate Athletes

Introduction: Proprioception (PP) and balance play a significant role in improving performance and preventing acute and chronic sport injuries. Muscle fatigue can be one of the factors that may interfere with signaling sensory input to the brain, and disturb the balance. The effect of muscle fatigue on this sensation has hardly been studied. The aim of this study was to investigate the effect of erector spinae muscle fatigue on the sensation (PP) of trunk, hip and knee among the male Karate athletes. Materials and Methods: 10 male karate athletes participating in Iranian national league matches were recruited in this study. Absolute error of active angles reconstruction (the trunk in 45 degrees of flexion, the hip in 30 degrees of abduction and flexion in open kinetic chain, and the knee in 30 and 60 degrees of flexion in closed kinetic chain) was measured by filming and analyzed, using AutoCAD software in pretest and posttest. Sorensen test was used as fatigue protocol. Results : The t test showed that erector spinea muscle fatigue had a significant effect on trunk flexion in 45 degrees (P = 0.046), and dominant (P = 0.001), and non-dominant (P = 0.001) hip joint in 30 degrees of abduction; but did not have any significant effect on positioning sensation of dominant (P = 0.434) and non-dominant (P = 0.703) hip flexion in 30 degrees, dominant (P = 0.148) and non-dominant (P = 0.204) knee flexion in 30 degrees, and dominant (P = 0.417) and non-dominant (P = 0.439) knee flexion in 60 degrees. Conclusion : According to the obtained results, erector spinae muscle fatigue in Karate athletes is likely to cause disruption in their trunk and hip position sensations, which can be the probable cause of lower-limbs injury and instability, particularly in the hips. Erector spinae muscle fatigue, however, may have no significant effect on knee position sensation or the injury potential of this joint.

The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients.

IntroductionChanges in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control.MethodsTwenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG).ResultsForce reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores.ConclusionsPatients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration stimulation during motor control exercises is likely to influence motor adaptation and could be considered in the treatment of cLBP. Further work is needed to clearly identify at what levels of the sensorimotor system these gains are achievable.

Análise espectral do sinal eletromiográfico do músculo eretor da espinha obtido do teste de Sorensen

INTRODUÇÃO: A fadigabilidade excessiva dos músculos lombares é um achado comum em pacientes portadores de dor lombar. Por isso, a avaliação da resistência isométrica desses músculos tem sido recomendada nessa população. OBJETIVO: O objetivo deste estudo foi identificar e analisar objetivamente o comportamento da fadiga do músculo eretor da espinha em um teste de resistência isométrica realizado até a exaustão. METODOLOGIA: Nove sujeitos saudáveis realizaram o teste de Sorensen modificado com contrações em intensidades correspondentes a 5%, 10%, 15% e 20% da contração voluntária máxima. A fadiga muscular foi identificada pela análise do comportamento da frequência mediana (FM) em função do tempo. RESULTADOS: O tempo de resistência isométrica foi inversamente correlacionado com a intensidade da contração. Contudo, a intensidade da contração não demonstrou efeito sobre a taxa de declínio da FM. A fadiga muscular foi significante em todas as porções do músculo eretor da espinha. Comparações entre os músculos eretor da espinha direito e esquerdo não revelaram diferenças significantes, enquanto que comparações entre porções do músculo eretor da espinha localizadas em diferentes níveis lombares revelaram maiores níveis de fadiga em L4-L5 bilateralmente. CONCLUSÃO: A análise espectral do sinal eletromiográfico foi eficaz para idenficação da fadiga do músculo eretor da espinha. Também foi possível identificar diferenças funcionais entre as diferentes porções desse músculo. O conhecimento dessas particularidades permite intervir de forma mais específica na prevenção e reabilitação dos distúrbios da coluna lombar.

Changes in the flexion-relaxation response induced by hip extensor and erector spinae muscle fatigue

BackgroundThe flexion-relaxation phenomenon (FRP) is defined by reduced lumbar erector spinae (ES) muscle myoelectric activity during full trunk flexion. The objectives of this study were to quantify the effect of hip and back extensor muscle fatigue on FRP parameters and lumbopelvic kinematics.MethodsTwenty-seven healthy adults performed flexion-extension tasks under 4 different experimental conditions: no fatigue/no load, no fatigue/load, fatigue/no load, and fatigue/load. Total flexion angle corresponding to the onset and cessation of myoelectric silence, hip flexion angle, lumbar flexion angle and maximal trunk flexion angle were compared across different experimental conditions by 2 × 2 (Load × Fatigue) repeated-measures ANOVA.ResultsThe angle corresponding to the ES onset of myoelectric silence was reduced after the fatigue task, and loading the spine decreased the lumbar contribution to motion compared to the hip during both flexion and extension. A relative increment of lumbar spine motion compared to pelvic motion was also observed in fatigue conditions.ConclusionsPrevious results suggested that ES muscles, in a state of fatigue, are unable to provide sufficient segmental stabilization. The present findings indicate that, changes in lumbar-stabilizing mechanisms in the presence of muscle fatigue seem to be caused by modulation of lumbopelvic kinematics.

Analysis of erector spinae muscle fatigue in healthy subjects in the sitting position

The aim of this study was to evaluate the frequency and amplitude of surface electromyography during erector spinae fatigue in healthy subjects in the sitting position. Eleven healthy males without low back pain participated in the study. The electromyographic parameters were collected with a surface electromyograph. Four electrodes were positioned lateral to the first and fifth lumbar vertebrae. The electromyographic signals were recorded during isometric trunk extension against a load cell in the sitting position. Loads of 50% and 75% of maximal voluntary isometric contraction were applied for 25 seconds to induce muscle fatigue. The signals processed using a Fast Fourier Transform algorithm and root mean square were submitted to linear regression to determine the fatigue index. The median frequency of the power spectrum presented negative values and the root mean square presented positive values, indicating muscle fatigue. No significant differences were observed when comparing level and side, or between loads (P > 0.05). The sitting position provides a better pelvis fixation and reproduces the usual position of occupational activities. The protocol used did not cause pain. Although all subjects presented erector spinae fatigue, no differences were observed between lumbar regions. The concomitant use of median frequency and root mean square in fatigue studies is suggested.

Gender differences in spectral and entropic measures of erector spinae muscle fatigue.

Electromyographic power spectral analysis is a valuable measurement; however, conflicting results have been reported for amplitude and frequency changes during a fatiguing submaximal muscle contraction. This study compared gender differences for two analyses in subjects with low back pain (LBP). Distinct gender differences are found in musculoskeletal illness/dysfunction, and we examined the effect of gender on entropy and median frequency (MF) slope in a cohort of subjects with LBP. A total of 44 subjects (24 female and 20 male) completed the modified Sorenson test. These subjects ranged in age from 26 to 64 years old, with an average age of 49.9 +/- 9.4 years. Overall, a significant fatigability difference was found based on MF slope (F = 21.33, p = 0.001) and entropy measures (F = 68.26, p = 0.001) of the back muscles. While the MF slope was not different (F = 0.44, p = 0.51) between genders, the entropy values were higher for the male subjects than for the female subjects (F = 6.70, p = 0.01). These results indicate that the Shannon entropy measure differentiates between genders. Further studies are needed to evaluate the effectiveness of using nonlinear analysis as a measurement tool.

Effects of erector spinae muscle fatigue on trunk repositioning accuracy in forward and lateral flexion

The present study was performed to evaluate the effects of erector spinae muscle fatigue on trunk repositioning accuracy. Trunk repositioning accuracy in forward and lateral flexion was measured in 25 healthy men using a 3-Space Fastrak (Polhemus Inc

Analysis of surface electromyography on repetitive lifting task-induced fatigue of back muscles

Using surface electromyography (SEMG) technique to evaluate repetitive lifting task-induced fatigue of back muscles. Thirteen volunteers lifted and lowered an 8 kg weight from floor to waist level for 100 times. Fatigue in the erector spinae muscles was quantified by comparing the frequency content of the EMG signal during static contractions performed before, and immediately after the 100 lifts. EMG average amplitude rose gradually during 100 lifts, the difference was significant at T10 right (P < 0.05) and L3 left (P < 0.01), the difference was not significant at T10 left and L3 right (P > 0.05). The median frequency intercept at T10 right, T10 left, L3 right, L3 left erector spinae muscles decreased by 2.0% (P > 0.05) 10.9% and 29.9% (P < 0.05), 27.9% (P < 0.01), respectively. The mean power frequency intercept decreased by 9% at L3 left erector spinae muscle (P < 0.05), the decrease was not statistically significant at other sites (P > 0.05). Repetitive lifting may induce measurable fatigue in the erector spinae muscles. Erector spinae muscle at L3 is more easily fatigued than at T10. Using the median frequency intercept to assess muscle fatigue is more sensitive than using mean power frequency intercept.

The effects of repetitive motion on lumbar flexion and erector spinae muscle activity in rowers

Objective. The purpose of this study was to investigate changes in lumbar flexion together with the pattern and level of muscle activity of selected erector spinae during a rowing trial. Design. Cross-sectional repeated measures design. Background. Low back pain is a common problem in rowers. The amount of lumbar flexion occurring during rowing might influence the possibility of injury. Methods. Sixteen young adult school rowers participated in the study. Changes in lumbar flexion and muscle activity were recorded across the drive phase, at three stages of an ergometer based rowing trial. Lumbar flexion was calculated by computerised motion analysis of surface markers attached to the spinous processes of L1 and S1. Surface electromyography techniques were used to examine the magnitude of activity from three erector spinae muscles. The median frequency of the electromyographic signal was examined to quantify fatigue in the erector spinae muscles during isometric maximal effort muscle activation prior to and after the rowing trial. Results. Lumbar flexion increased significantly ( P<0.05) during the rowing trial, as did the magnitude of electromyographic activity from sites over the lumbar multifidus, iliocostalis lumborum and longissimus thoracis muscles. The median frequency decreased significantly ( P<0.05) in each muscle examined. Conclusions. The findings showed that rowers attain relatively high levels of lumbar flexion during the rowing stroke, and these levels are increased during the course of the rowing trial. Indirect evidence of muscle fatigue in erector spinae muscles was also apparent, and this observation may in part be responsible for the increased levels of lumbar flexion observed. Relevance Excessive lumbar flexion may influence the potential for injury to spinal structures. An awareness of increased lumbar flexion and muscle fatigue in the erector spinae muscles may be important for injury prevention programs for rowers.

Quantification of erector spinae muscle fatigue during prolonged, dynamic lifting tasks.

A method was developed to quantify erector spinae fatigue resulting from repetitive dynamic lifting in the sagittal plane. This method was tested with the data from eight male subjects lifting inertial loads of 19 kg and 17 kg during sessions of 20 min and 2 h, respectively. Surface EMG electrodes were applied over sites representing the bilateral lumbar and thoracic erector spinae and external oblique muscles. Maximal and submaximal isometric trunk extensor contractions were performed at the start, intermittently throughout, and at the end of the dynamic lifting trials, within an apparatus designed to control spine posture in the upright standing position. These exertions were used to assess the decreases in strength, endurance and EMG mean power frequency (fw) as well as the increases in EMG amplitude that have been shown to accompany muscle fatigue. The average of the group for extensor strength decreased 17% and 21% (P < 0.05) and the endurance times decreased 60% and 62% (P < 0.01) for the 2-h and the 20-min session, respectively. The average endurance time decreased at least 10% for each subject in each session. Strength decreased at least 10% in all but 2 of 16 cases (both in the 20-min session). The average decreases in fw were 12% (lumbar) and 17% (thoracic; P < 0.05) in the 2-h sessions and 20% (lumbar; P < 0.05) and 14% (thoracic) in the 20-min sessions. There was also a significant increase in EMG amplitude (P < 0.05) for both muscle group in both sessions.(ABSTRACT TRUNCATED AT 250 WORDS)