scholarly journals HDsEMG Activity of the Lumbar Erector Spinae in Violin Players: Comparison of Two Chairs

2019 ◽  
Vol 34 (4) ◽  
pp. 205-214 ◽  
Author(s):  
Alessandro Russo ◽  
Alejandra Aranceta-Garza ◽  
Samuel D’Emanuele ◽  
Francesca Serafino ◽  
Roberto Merletti
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Erector Spinae ◽  
Mean Square ◽  
Electrode Arrays ◽  
Spatial And Temporal Patterns ◽  
Rates Of Change ◽  
Density Surface ◽  
The Mean ◽  
Spectral Frequency

This study compared an ergonomic alternative chair (A-chair) with a standard orchestra chair (O-chair) used by a group of 9 violin players. The features of the high-density surface EMG (HDsEMG) of the lumbar erector spinae muscles were used for the comparison. The violinists played the same pieces of music for 2 hrs without interruption on each chair in 2 different days, 1 week apart. HDsEMG was recorded for 20 s every 5 minutes using two electrode arrays of 16 × 8 electrodes each, one on each side of the spine and placed between the T11 and L4 levels. The sEMG was non-stationary and burst-like patterns were observed on 8 out of 9 violinists. The mean root mean square (RMS) and mean spectral frequency (MNF) value over the region of activity (ROA), the centroid of the ROA, the rates of change in time of the spatial mean of the RMS and MNF values, and the burst frequencies associated with the two chairs were compared. Statistically significant reductions of RMS were observed in each violinist between the O-chair and A-chair (range 11.80−78.36%). No significant changes of other spatial or spectral sEMG features were globally observed versus time or between chairs but were demonstrated by some subjects. It is concluded that the A-chair is associated with a decrease of the sEMG amplitude of the ESM without changes of the spatial and temporal patterns of muscle activation.

scholarly journals Trunk Muscle Activity in One- and Two-Armed American Kettlebell Swing in Resistance-Trained Men

2019 ◽  
Vol 03 (01) ◽  
pp. E12-E18
Author(s):  
Vidar Andersen ◽  
Marius Fimland ◽  
Atle Saeterbakken
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Contralateral Side ◽  
Trunk Muscle ◽  
Rectus Abdominis ◽  
Erector Spinae ◽  
Oblique Muscle ◽  
Ipsilateral Side ◽  
External Oblique ◽  
The One

AbstractThe aim of the study was to compare the one-armed vs. two-armed American kettlebell swing on trunk muscle activation. Fifteen resistance-trained men performed ten repetitions of both exercises using a 14-kg kettlebell. Surface EMG from the erector spinae, rectus abdominis and external oblique muscles were collected on both sides of the trunk. The erector spinae activation during the one-armed swing was 14–25% higher on the contralateral compared to the ipsilateral side in both exercises (Cohen’s d effect size [ES]=0.41–0.71, p ˂ 0.001–0.034). Further, the contralateral side was 14% more activated during the two-armed swing compared to the ipsilateral side during the one-armed swing (ES=0.43, p=0.009). For the rectus abdominis muscle, the two-armed swing induced higher activation of the rectus abdominis compared to the one-armed swing on both the contralateral (40%, ES=0.48, p=0.040) and ipsilateral side (59%, ES=0.83, p=0.002). There were no differences for the external oblique muscle (p=0.495–0.662). In conclusion, the trunk activation patterns of the two exercises were different, which could be explained by different biomechanics in the two exercises, and could thus have complimentary effects. We recommend that both unilateral and bilateral execution of the American kettlebell swing is included over time.

Wearing an Inflatable Vest Alters Muscle Activation and Trunk Angle While Paddling a Surfboard

2017 ◽  
Vol 33 (4) ◽  
pp. 282-287 ◽  
Author(s):  
Jeff A. Nessler ◽  
Thomas Hastings ◽  
Kevin Greer ◽  
Sean C. Newcomer
Keyword(s):  
Muscle Activation ◽  
Random Order ◽  
Surface Emg ◽  
Erector Spinae ◽  
Low Back ◽  
Upper Trapezius ◽  
Lower Back ◽  
The Right ◽  
Trunk Extension ◽  
Order Surface

Low back pain is a commonly reported problem among recreational surfers. Some individuals report that wearing a vest with an inflatable bladder that alters trunk angle may help to alleviate pain. The purpose of this study was to determine whether such a vest has an effect on muscle activation and extension of the lower back. Twelve recreational surfers completed 12 paddling trials at 1.1 m/s in a swim flume on both a shortboard and a longboard on 2 separate days. Three conditions of no vest, vest uninflated, and vest inflated were presented to participants in random order. Surface EMG and trunk angle were acquired via wireless sensors placed over the right erector spinae, mid-trapezius, upper trapezius, and latissimus dorsi. Wearing the inflated vest affected muscle activation: erector spinae and mid-trapezius demonstrated a significant decrease in activation relative to wearing no vest (12% and 18% respectively, p < .05). Trunk extension was also significantly reduced when the vest was inflated (18% reduction, p < .05). Results were similar for both the short and longboard, though this effect was greater while paddling the larger board. These results suggest that a properly inflated vest can alter trunk extension and muscle activity while paddling a surfboard in water.

Evaluating the Relationship Between Muscle Activation and Spine Kinematics Through Wavelet Coherence

2016 ◽  
Vol 32 (5) ◽  
pp. 526-531 ◽  
Author(s):  
Dean C. Hay ◽  
Mark P. Wachowiak ◽  
Ryan B. Graham
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Wavelet Coherence ◽  
Motion Patterns ◽  
Time Frequency ◽  
Spine Kinematics ◽  
Internal Oblique ◽  
The Relationship

Advances in time-frequency analysis can provide new insights into the important, yet complex relationship between muscle activation (ie, electromyography [EMG]) and motion during dynamic tasks. We use wavelet coherence to compare a fundamental cyclical movement (lumbar spine flexion and extension) to the surface EMG linear envelope of 2 trunk muscles (lumbar erector spinae and internal oblique). Both muscles cohere to the spine kinematics at the main cyclic frequency, but lumbar erector spinae exhibits significantly greater coherence than internal oblique to kinematics at 0.25, 0.5, and 1.0 Hz. Coherence phase plots of the 2 muscles exhibit different characteristics. The lumbar erector spinae precedes trunk extension at 0.25 Hz, whereas internal oblique is in phase with spine kinematics. These differences may be due to their proposed contrasting functions as a primary spine mover (lumbar erector spinae) versus a spine stabilizer (internal oblique). We believe that this method will be useful in evaluating how a variety of factors (eg, pain, dysfunction, pathology, fatigue) affect the relationship between muscles’ motor inputs (ie, activation measured using EMG) and outputs (ie, the resulting joint motion patterns).

Trunk Muscle Activation While Resisting Asymmetrically Applied Loads in an Axially Rotated Posture

1992 ◽  
Vol 36 (10) ◽  
pp. 752-756
Author(s):  
Steven A. Lavender ◽  
Yang-Hwei Tsuang ◽  
Gunnar B.J. Andersson
Keyword(s):  
Muscle Activation ◽  
Surface Emg ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Rectus Abdominus ◽  
Left And Right ◽  
External Oblique ◽  
The Right ◽  
Main Effects ◽  
Univariate Analyses

The present investigation describes the electromyographic (EMG) response of eight trunk muscles during the application of loads to the torso while subjects maintained a twisted posture. The external moments of 20 and 40 Nm were applied to a harness system as each of the 10 subjects twisted 25 degrees. The applied moment direction was varied in 3 0 degree increments completely around the subjects (0 to 33 0 degrees). Surface EMG was used to monitor the left and right Latissimus Dorsi, Erector Spinae, External Oblique, and Rectus Abdominus. Multivariate and univariate analyses of variance (MANOVA and ANOVA) procedures showed significant main effects for all muscles and a significant moment magnitude by moment direction interaction effect in 6 of the 8 muscles. The greatest muscle activity was observed in the right Erector Spinae and the left External Oblique muscles. The results are also compared with an earlier study in which a similar loading paradigm was used as subject maintained a neutral upright posture.

Effect of Unilateral Non-Rhythmical Stimulation on Bilateral Cerebral Cortex and Muscle Activation in People

2014 ◽  
Vol 19 ◽  
pp. 25-33
Author(s):  
Jian Feng Sui ◽  
Ya Li Liu ◽  
Lin Hong Ji
Keyword(s):  
Cerebral Cortex ◽  
Muscle Activation ◽  
Neurological Diseases ◽  
Relative Displacement ◽  
Surface Emg ◽  
Average Value ◽  
Support Plate ◽  
Cortex Area ◽  
History Of ◽  
The Mean

Effects of conventional exercise training of robot to stroke patients are not too satisfying, and efficient methods of training are unclear. To test how the non-rhythmical load stimulation affects cerebral cortex by analyzing the coherence between electroencephalographic signals (EEGs) and electromyographic signals (EMGs). Ten healthy subjects, all subjects have no history of neurological diseases (6 men and 4 women, mean age: 24.5 years, range: 22-28). Subjects lay on the experimental platform 75°with respect to the ground, feet on support plates and close to the ground. When non-rhythmical stimulation was performed randomly, one hinge was released and the respected braced force between the foot and support plate disappeared, which caused the corresponding ankle to extend suddenly without relative displacement between the foot and the support plate. Surface EMG signals from tibialis anterior (TA) muscles and EEG signals from cerebral cortex area Cz were recorded, and coherence between them were analyzed. The mean maximum EEG-EMG coherence of the non-rhythmical stimulation side of the ten subjects was consistent across all (9 of 10) within β range (13-30 Hz), and the average value of all in the stimulated side was 23.581Hz. While the mean maximum EEG-EMG coherence of the still side were consistent across all (9 of 10) within α range (8-13 Hz). Our findings suggest that non-rhythmical stimulation to lower limb can stimulate effectively the corresponding area of the cerebral cortex, and this idea could be applied in rehabilitation of central nervous system diseases like stroke.

scholarly journals Muscle activation in specific regions of the trapezius during modified Kendall manual muscle tests

2021 ◽  
Author(s):  
Zachariah J. Henderson ◽  
Sarah Bohunicky ◽  
Josee A. Rochon ◽  
Mark Dacanay ◽  
Trisha D. Scribbans
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
The Other ◽  
Muscle Fibres ◽  
Isometric Contractions ◽  
Mean Square ◽  
Healthy Individuals ◽  
Maximal Contraction ◽  
Density Surface ◽  
Shoulder Pathologies

Abstract Context: Manual muscle tests (MMTs) are often used when assessing shoulder pathologies. For the trapezius, individual MMTs are used to selectively test the upper (UTR), middle (MTR), and lower (LTR) trapezius regions. It is assumed that MMTs for each region preferentially recruit the corresponding muscle fibres and produce a “maximal” contraction; however, it is unknown if this is true. Objective: To determine if maximum voluntary isometric contractions (MVICs) for the upper (UT-MVIC), middle (MT-MVIC), and lower (LT-MVIC) trapezius, adapted from the Kendall MMTs, recruit the corresponding trapezius regions. Design: Cross-Over. Setting: Laboratory. Participants: 20 young, healthy individuals. Intervention: Participants performed three repetitions of each MVIC. High density surface electromyography was collected from the UTR, MTR, and LTR. Main Outcome Measures: Root mean square (excitation) of the UTR, MTR, and LTR. Statistical Analysis: Three, one-way repeated measures ANOVAs. Results: UTR excitation: There was a significant increase in UTR excitation during the LT-MVIC compared to the UT-MVIC (p = .016), and MT-MVIC (p &lt; .001). MTR excitation: There was a significant increase in MTR excitation during the MT-MVIC compared to the UT-MVIC (p = .001), and a significant increase in MTR excitation during the LT-MVIC compared to the UT-MVIC (p &lt; .001). There was also a significant increase in MTR excitation during the LT-MVIC compared to the MT-MVIC (p &lt; .001). LTR excitation: There was a significant increase in LTR excitation during the MT-MVIC (p &lt; .001) and LT-MVIC (p &lt; .001) compared to the UT-MVIC. Conclusions: The UT-MVIC and MT-MVIC do not necessarily recruit the corresponding trapezius regions more than the other MVICs. Rather, the LT-MVIC appears to produce the greatest excitation in all trapezius regions. Additional research is needed; however, clinicians should be aware that maximal contractions may not always recruit the desired musculature when forming a clinical interpretation.

The Bordeaux Automatic Meridian Circle

1978 ◽  
Vol 48 ◽  
pp. 227-228
Author(s):  
Y. Requième
Keyword(s):  
Mean Square Error ◽  
Mean Square ◽  
Meridian Circle ◽  
The Mean ◽  
Full Automation

In spite of important delays in the initial planning, the full automation of the Bordeaux meridian circle is progressing well and will be ready for regular observations by the middle of the next year. It is expected that the mean square error for one observation will be about ±0.”10 in the two coordinates for declinations up to 87°.

The mean-square generalized delayed decision feedback sequence detector

2003 ◽  
Vol 14 (3) ◽  
pp. 265-268 ◽  
Author(s):  
Maurizio Magarini ◽  
Arnaldo Spalvieri ◽  
Guido Tartara
Keyword(s):  
Decision Feedback ◽  
Mean Square ◽  
The Mean

Limit tolerances for sums of measurement errors

2018 ◽  
Vol 934 (4) ◽  
pp. 59-62
Author(s):  
V.I. Salnikov
Keyword(s):  
Normal Distribution ◽  
Mean Square Error ◽  
Gaussian Distribution ◽  
Measurement Errors ◽  
Theory And Practice ◽  
Mean Square ◽  
The Mean ◽  
Limiting Values ◽  
Limiting Value

The question of calculating the limiting values of residuals in geodesic constructions is considered in the case when the limiting value for measurement errors is assumed equal to 3m, ie ∆рred = 3m, where m is the mean square error of the measurement. Larger errors are rejected. At present, the limiting value for the residual is calculated by the formula 3m√n, where n is the number of measurements. The article draws attention to two contradictions between theory and practice arising from the use of this formula. First, the formula is derived from the classical law of the normal Gaussian distribution, and it is applied to the truncated law of the normal distribution. And, secondly, as shown in [1], when ∆рred = 2m, the sums of errors naturally take the value equal to ?pred, after which the number of errors in the sum starts anew. This article establishes its validity for ∆рred = 3m. A table of comparative values of the tolerances valid and recommended for more stringent ones is given. The article gives a graph of applied and recommended tolerances for ∆рred = 3m.

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