Effects of Voluntary Activation on Neuromuscular Endurance Analyzed by Surface Electromyography

2002 ◽  
Vol 95 (2) ◽  
pp. 613-619 ◽  
Author(s):  
Hiroshi Yamada ◽  
Kimihiro Kaneko ◽  
Tadashi Masuda
Keyword(s):  
Surface Electromyography ◽  
Muscle Activation ◽  
Voluntary Activation ◽  
Initial Value ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Endurance Time ◽  
Voluntary Muscle ◽  
Power Frequency ◽  
Maximum Voluntary Torque

The purpose was to examine the relation between voluntary muscle activation and neuromuscular endurance of individual subjects based on the pattern of surface electromyography (EMG). The voluntary muscle activation was estimated from the relation between voluntary force and tetanic force superimposed on the voluntary force (twitch interpolation technique). 11 male subjects (10 regular exercisers and 4 sedentary; 21–29 years old) were divided into a High Voluntary Activation group and a Low Voluntary Activation group. A significant positive correlation of .72 (p<.01) was found between maximum voluntary torque and voluntary activation. A fatigue test was conducted during isometric contractions of 60% and 20% maximum voluntary torque. The endurance time was significantly longer for the Low Voluntary Activation group than the High Voluntary Activation group. The mean power frequency of voluntary EMG obtained from the vastus lateralis muscle decreased consistently whereas the average rectified value increased. The final change of mean power frequency relative to the initial value was significantly greater in the 60% Fatigue task than in the 20% Fatigue task. For the 60% Fatigue task, the final change of mean power frequency and average rectified value relative to the initial value was significantly greater in the Low Voluntary Activation group than in the High Voluntary Activation group. These results suggest that the individual differences in voluntary activation determine the neuromuscular performance usually evaluated as maximum voluntary torque and endurance time and that the voluntary activation may depend on the daily exercise.

Aircraft Passenger Comfort Based on Muscle Activation and Perceived Discomfort During Long Flights

2020 ◽  
Vol 91 (5) ◽  
pp. 416-421
Author(s):  
Huining Pei ◽  
Suihuai Yu ◽  
Man Ding ◽  
Zhonghang Bai
Keyword(s):  
Muscle Activation ◽  
Upper Body ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Passenger Comfort ◽  
Body Regions ◽  
Lower Back ◽  
Significant Difference ◽  
Power Frequency ◽  
Subjective Discomfort

OBJECTIVE: The purpose of this study was to investigate the comfort of aircraft passengers during long flights and to determine the effects of the seatback angle and the seat pitch on passengers’ upper body muscles (neck, shoulder, and lower back) and subjective comfort.METHODS: All subjects sat on an aircraft seat for 2 h with different levels of seatback angle and seat pitch. Subjective discomfort scores and root mean square (RMS) and mean power frequency (MPF) values were used to evaluate muscle fatigue, and all data were calculated for every 15-min interval.RESULTS: Significant increases of MPF for all three muscles were found at 30 min, along with significant increases in the perceived levels of discomfort (PLD) over 2 h. Besides, a 120° seatback angle and a 34˝ seat pitch resulted in lower PLD values for the lower back and hip areas than smaller ones (significant difference).DISCUSSION: It took around 30 min before pronounced discomfort in the upper body regions occurred during flight. The larger parameters of seatback angle and seat pitch may significantly contribute to the easing of subjective discomfort. Moreover, a decrease in MPF coupled with a concomitant increase in RMS does not appear to be a reliable indicator of discomfort rate. The need for further development of discomfort indicators which are more directly related to muscular activation is recognized.Pei H, Yu S, Ding M, Bai Z. Aircraft passenger comfort based on muscle activation and perceived discomfort during long flights. Aerosp Med Hum Perform. 2020; 91(5):416–421.

Muscular endurance and surface electromyogram in isometric and dynamic exercise

1981 ◽  
Vol 51 (1) ◽  
pp. 1-7 ◽  
Author(s):  
M. Hagberg
Keyword(s):  
Maximum Voluntary Contraction ◽  
Isometric Exercise ◽  
Voluntary Contraction ◽  
Dynamic Exercise ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Endurance Time ◽  
Significant Difference ◽  
Power Frequency ◽  
The Mean

In nine male volunteers, the endurance time for sustained isometric exercise (right-angle elbow flexion) and dynamic exercise (continuous concentric and eccentric elbow flexions) was measured at different contraction levels. Intermittent isometric exercises were also performed by four of the subjects in whom surface electromyographic elbow flexor recordings were obtained during the three types of exercise. A rapid decrease of the endurance time was seen at contraction levels above 15–20% of the maximum voluntary contraction for both the sustained isometric and dynamic exercise. There were no significant difference between the regression of the endurance time vs. the contraction level for the sustained isometric exercise and that of the dynamic exercise. However, the endurance time was enhanced in the intermittent isometric exercise compared with the sustained isometric exercise. The development of muscle fatigue was well correlated to change of the myoelectric rootmean-square amplitude and the mean power frequency. Differences in exercise did not significantly affect the relation between the time constant of the mean power frequency decrease and the endurance time.

Dependence of the mean power frequency of the electromyogram on muscle force and fibre type

1991 ◽  
Vol 142 (4) ◽  
pp. 457-465 ◽  
Author(s):  
B. GERDLE ◽  
K. HENRIKSSON-LARSÉN ◽  
R. LORENTZON ◽  
M.-L. WRETLING
Keyword(s):  
Fibre Type ◽  
Muscle Force ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Power Frequency ◽  
The Mean

Surface electromyogram power spectrum in human quadriceps muscle during incremental exercise

1993 ◽  
Vol 74 (6) ◽  
pp. 2704-2710 ◽  
Author(s):  
D. Gamet ◽  
J. Duchene ◽  
C. Garapon-Bar ◽  
F. Goubel
Keyword(s):  
Principal Component ◽  
Quadriceps Muscle ◽  
Bicycle Ergometer ◽  
Linear Increase ◽  
Total Power ◽  
Test Surface ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Incremental Test ◽  
Power Frequency

Spectral electromyographic (EMG) changes in human quadriceps muscles were studied to reinvestigate discrepant results concerning mean power frequency (MPF) changes during dynamic exercise. An incremental test consisting of a quasi-linear increase in mechanical power on a bicycle ergometer (for 20–100% of maximal aerobic power) was performed by forty subjects. During this test, surface EMGs from the quadriceps muscles showed that EMG total power (PEMG) increased with a curvilinear pattern for every subject, whereas MPF kinetics varied from one subject to another. PEMG changes had the same shape, which would lead to disappointing results in terms of discrimination between subjects. The ability of normalized MPF kinetics to define significant clusters of subjects was tested using a principal component analysis. This analysis led to the projection of all experiments onto a plane and revealed a relevant grouping of MPF profiles. Differences in MPF kinetics between clusters are interpreted in terms of various possibilities of balance between physiological events leading to an increase or a decrease in MPF.

Mean power frequency during speech in myalgia patients

2010 ◽  
Vol 37 (9) ◽  
pp. 692-697 ◽  
Author(s):  
E. SUZUKI ◽  
S. ISHIGAKI ◽  
H. YATANI ◽  
E. MORISHIGE ◽  
M. UCHIDA
Keyword(s):  
Mean Power ◽  
Mean Power Frequency ◽  
Power Frequency

Interlimb Neuromuscular Responses During Fatiguing, Bilateral, Leg Extension Exercise at a Moderate Versus High Load

Motor Control ◽  
2021 ◽  
Vol 25 (1) ◽  
pp. 59-74
Author(s):  
Taylor K. Dinyer ◽  
Pasquale J. Succi ◽  
M. Travis Byrd ◽  
Caleb C. Voskuil ◽  
Evangeline P. Soucie ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
High Load ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Leg Extension ◽  
Neuromuscular Responses ◽  
Power Frequency ◽  
The Central Nervous System ◽  
Common Drive ◽  
Repetitions To Failure

This study determined the load- and limb-dependent neuromuscular responses to fatiguing, bilateral, leg extension exercise performed at a moderate (50% one-repetition maximum [1RM]) and high load (80% 1RM). Twelve subjects completed 1RM testing for the bilateral leg extension, followed by repetitions to failure at 50% and 80% 1RM, on separate days. During all visits, the electromyographic (EMG) and mechanomyographic (MMG), amplitude (AMP) and mean power frequency (MPF) signals were recorded from the vastus lateralis of both limbs. There were no limb-dependent responses for any of the neuromuscular signals and no load-dependent responses for EMG AMP, MMG AMP, or MMG MPF (p = .301–.757), but there were main effects for time that indicated increases in EMG and MMG AMP and decreases in MMG MPF. There was a load-dependent decrease in EMG MPF over time (p = .032) that suggested variability in the mechanism responsible for metabolite accumulation at moderate versus high loads. These findings suggested that common drive from the central nervous system was used to modulate force during bilateral leg extension performed at moderate and high loads.

THE EFFECT OF FOREARM FLEXION ANGLE ON THE MMG AND EMG MEAN POWER FREQUENCY

2002 ◽  
Vol 34 (5) ◽  
pp. S263
Author(s):  
K T. Ebersole ◽  
T J. Housh ◽  
G O. Johnson ◽  
J T. Cramer ◽  
S R. Perry ◽  
...  
Keyword(s):  
Flexion Angle ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Power Frequency
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