On-Line Monitoring of the Median Frequency of the Surface EMG Power Spectrum

1985 ◽  
Vol BME-32 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roberto Merletti ◽  
Domenico Biey ◽  
Mario Biey ◽  
Giuseppe Prato ◽  
Andrea Orusa
Keyword(s):  
Power Spectrum ◽  
Surface Emg ◽  
Median Frequency ◽  
On Line ◽  
Emg Power Spectrum

Conduction velocity and EMG power spectrum changes in fatigue of sustained maximal efforts

1981 ◽  
Vol 51 (5) ◽  
pp. 1300-1305 ◽  
Author(s):  
B. Bigland-Ritchie ◽  
E. F. Donovan ◽  
C. S. Roussos
Keyword(s):  
Power Spectrum ◽  
Conduction Velocity ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Mass Action ◽  
Wave Form ◽  
Muscle Temperature ◽  
Voluntary Activity ◽  
Adductor Pollicis Muscle ◽  
Emg Power Spectrum

The relationship between the electromyographic (EMG) power spectrum and muscle conduction velocity was investigated during both fatiguing and nonfatiguing contractions of the adductor pollicis muscle. Changes in the EMG power spectrum were measured by Fourier transform analysis and by comparing the power in the high (130–238 Hz) and low (20--40 Hz) frequency bands. Changes in conduction velocity were measured during voluntary activity from changes in the muscle mass action potential evoked by periodic maximal shocks to the nerve. This was varied independently either by maintaining a 60-s fatiguing maximal voluntary contraction involving 30--50% loss of force or by changing muscle temperature in the absence of fatigue. Both procedures resulted in similar changes in the power spectrum. However, the change in conduction velocity required to generate equal changes in the EMG was about 10 times greater in the absence of fatigue than those observed during a 60-s maximum contraction initiated at any initial muscle temperature. This suggests that during fatigue of maximal voluntary contractions, factors other than changes in the wave form of individual muscle fiber action potentials must contribute to the observed shift in the total surface EMG frequency components.

Surface EMG crosstalk quantified at the motor unit population level for muscles of the hand, thigh, and calf

2021 ◽  
Author(s):  
Carina Marconi Germer ◽  
Dario Farina ◽  
Leonardo Abdala Elias ◽  
Stefano Nuccio ◽  
François Hug ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Motor Unit ◽  
Population Level ◽  
Motor Units ◽  
Spatial Filtering ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Plantar Flexors ◽  
Emg Power Spectrum

Crosstalk is an important source of error in interpreting surface electromyography (EMG) signals. Here, we aimed at characterizing crosstalk for three groups of synergistic muscles by the identification of individual motor unit action potentials. Moreover, we explored whether spatial filtering (single and double differential) of the EMG signals influences the level of crosstalk. Three experiments were conducted. Participants (total twenty-five) performed isometric contractions at 10% of the maximal voluntary contraction (MVC) with digit muscles and knee extensors, and at 30% MVC with plantar flexors. High-density surface EMG signals were recorded and decomposed into motor unit spike trains. For each muscle, we quantified the crosstalk induced to neighboring muscles and the level of contamination by the nearby muscle activity. We also estimated the influence of crosstalk on the EMG power spectrum and intermuscular correlation. Most motor units (80%) generated significant crosstalk signals to neighboring muscle EMG in monopolar recording mode, but this proportion decreased with spatial filtering (50% and 42% for single and double differential, respectively). Crosstalk induced overestimations of intermuscular correlation and has a small effect on the EMG power spectrum, which indicates that crosstalk is not reduced with high-pass temporal filtering. Conversely, spatial filtering diminished the crosstalk magnitude and the overestimations of intermuscular correlation, confirming to be an effective and simple technique to reduce crosstalk. This paper presents a new method for the identification and quantification of crosstalk at the motor unit level and clarifies the influence of crosstalk on EMG interpretation for muscles with different anatomy.

Ankle angle effects on endurance time, median frequency and mean power of gastrocnemius EMG power spectrum: a comparison between individual and group analysis

Ergonomics ◽  
1987 ◽  
Vol 30 (8) ◽  
pp. 1149-1159 ◽  
Author(s):  
PETRA C. MATTHIJSSE ◽  
KARIN M. M. HENDRICH ◽  
WIM H. RIJNSBURGER ◽  
REINOUT D. WOITTIEZ ◽  
PETER A. HUIJING
Keyword(s):  
Power Spectrum ◽  
Group Analysis ◽  
Median Frequency ◽  
Mean Power ◽  
Endurance Time ◽  
Ankle Angle ◽  
Emg Power Spectrum

The Effects of High-Heeled Posture on COP Kinematics and Muscle Fatigue during the Balance Control of Human Body

2006 ◽  
Vol 321-323 ◽  
pp. 1119-1122 ◽  
Author(s):  
Hyeon Ki Choi ◽  
Won Hak Cho
Keyword(s):  
Power Spectrum ◽  
Muscle Fatigue ◽  
Postural Balance ◽  
Tibialis Anterior ◽  
Control Mechanism ◽  
Center Of Pressure ◽  
Balance Control ◽  
Control Problems ◽  
Median Frequency ◽  
Emg Power Spectrum

This study addressed the effect of balance control problems on the high-heeled women. The specific purposes of this study are to quantify the displacements and velocities of center-of-pressure (COP) of a body during waist pulling perturbation and to compare the differences between the bare-feet and the high-heeled. Another purpose of the study is to identify the effects of a high-heeled posture on electromyography (EMG) activities and muscle fatigue. We used a waist pulling system which has three different magnitudes to sway the subjects. The COP displacement of a high-heeled posture was about twice as much as that of bare-feet posture. Also the COP velocity of a high-heeled posture became about twice as much as that of bare-feet posture. Muscle fatigue could be identified by the shift of the median frequency (MF) of the EMG power spectrum toward lower frequencies. Median frequency of the EMG power spectrum from tibialis anterior was reduced more rapidly during high-heeled situation than during bare-feet situation. COP kinematics and muscle fatigue analysis in postural balance researches are considered to provide useful information in understanding the balance control mechanism of women’s high-heeled posture.

EMG Power Spectrum Patterns of Anterior Temporal and Masseter Muscles in Children and Adults

1989 ◽  
Vol 68 (5) ◽  
pp. 800-804 ◽  
Author(s):  
S.W.H. Yuen ◽  
J.C.C. Hwang ◽  
P.W.F. Poon
Keyword(s):  
Power Spectrum ◽  
Fiber Type ◽  
Surface Emg ◽  
Masticatory Muscles ◽  
Craniofacial Morphology ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Emg Power Spectrum ◽  
And Gender ◽  
Masseter Muscles

The power spectrum of electromyograms (EMG) has been demonstrated to vary with muscles having different muscle fiber type compositions. This study investigated the variations in EMG power spectrum patterns of the masticatory muscles with age and gender by comparison of the mean power frequency (MPF) of the anterior temporal and masseter muscles in children and adults. Surface EMG signals were sampled bilaterally from the muscles when the subjects were performing maximum voluntary isometric clenches at maximal intercuspal position. The results indicated that MPF values were age-dependent (p<0.001), and sexual dimorphism was evident (p<0.001), with lower MPF values in male and adult muscles. While male adults had the lowest and female children had the highest MPF values, female adults had MPF values closer to values obtained from male children. These differences or similarities could be attributed to the degree of differentiation of the muscles during growth and development of the craniofacial morphology.

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