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

Bigland-Ritchie, B.; Donovan, Edward F.; Roussos, Charis

doi:10.1152/jappl.1981.51.5.1300

Cited by 374 publications

(227 citation statements)

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“…This suggests that, during failing weaning trials, a fatigue process is initiated peripherally into the respiratory muscles. When associated with the slowing of MRR, it is likely that the central drive is modulated [94].…”

Section: The Final Pathway To Weaning Failure: Fatigue/hypercapnia/dymentioning

confidence: 99%

Respiratory muscles and weaning failure

Vassilakopoulos¹,

Zakynthinos²,

Roussos³

1996

Eur Respir J

118

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R Re es sp pi ir ra at to or ry y m mu us sc cl le es s a an nd d w we ea an ni in ng g f fa ai il lu ur re e ABSTRACT: Weaning failure is, unfortunately, a rather common phenomenon for mechanically-ventilated patients (especially those with chronic obstructive pulmonary disease (COPD)), and the respiratory muscles play a pivotal role in its development.Weaning fails whenever an imbalance exists between the ventilatory needs and the neurocardiorespiratory capacity. This can happen if there is an increase in the energy demands of the respiratory muscles, a decrease in the energy available, a decrease in neuromuscular competence, or if the respiratory muscles pose an impediment to the heart and blood flow.The imbalance created will lead to weaning failure through the development of respiratory muscle fatigue, hypercapnia, dyspnoea, anxiety and organ dysfunction.

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Section: The Final Pathway To Weaning Failure: Fatigue/hypercapnia/dymentioning

confidence: 99%

Respiratory muscles and weaning failure

Vassilakopoulos¹,

Zakynthinos²,

Roussos³

1996

Eur Respir J

118

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“…This suggests that the electrophysiological mechanism of muscle contraction remains intact till the end. It is due to a significant decline in force output that the synchronization of motor unit occurs 12,28 to maximize the electrical impact on the contractile phenomenon. Univariate ANOVA for all objective variables revealed that the gender was a strong determinant.…”

Section: Discussionmentioning

confidence: 99%

“…An accompanying increase in EMG amplitude has also been considered a quantitative measure of fatigue 5,6,9,10 . Other spectral parameters of the EMG signal such as mean power frequency 11 , the ratio of low frequency to high frequency 12 and the number of zero crossings 13 have also been used in some studies as indices of muscle fatigue but were found to be more affected by noise than the measure of median frequency 14 . Though among EMG variables the slope of decline of the median frequency in sustained contractions has been considered as an index of fatigue, when it is compared against the standard of inability to hold or maintain a force the slope of MF decline does not mirror it 5,6 .…”

Section: Introductionmentioning

confidence: 99%

Localized muscle fatigue: review of three experiments

Kumar

2006

Rev. bras. fisioter.

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Background: Fatigue considerably affects rehabilitation and ergonomics. Many approaches to this complex phenomenon, ranging from physiological to psychological, have been used to obtain meaningful fatigue measurements. However, none of the methods in the literature measure fatigue directly. It is therefore of considerable interest to determine which indirect methods best represent the state. Method: Fatiguing contraction was measured at maximum voluntary contraction (MVC) and 40% MVC in the biceps brachii, quadriceps and erector spinae muscles (three separate experiments). The most-reported objective measurements (contraction force, median electromyographic frequency, heart rate, muscle bed oxygenation and muscle blood volume) and subjective measurements (visual analog score, body part discomfort rating and perceived exertion rate) were simultaneously recorded. The data from the three experiments underwent separate statistical analysis. Descriptive statistics, linear mixed effects (to examine force fatigue predictability) and trend analysis (with between and within-subject correlations) were calculated. Results: Univariate ANOVA on all objective variables showed that gender was a significant factor (p<0.001). All subjective and objective variables were significant (p<0.05-0.001) in predicting force fatigue. However, the percentage variability explained remained small. By combining variables, the variability explained increase to between 60.2% and 71.9%. Correlations between variables were small but significant (p<0.05-0.001). Among single variables, median electromyographic frequency was a slightly better predictor of MVC fatigue (p<0.001) and visual analog score for sub-MVC (p<0.001). Conclusion: It is desirable not to measure or predict fatigue based on one variable alone. Combining variables improves measurement and prediction. Single-variable indexing of localized muscle fatigue is problematic.

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“…30,31 Considering the intensity of the exercise, synchronization of motor units is not a plausible hypothesis because it occurs when motor units are close to exhaustion. 30,32 There- …”

Section: Moderate Exercisementioning

confidence: 99%

Changes in oxygen uptake, shoulder muscles activity, and propulsion cycle timing during strenuous wheelchair exercise

et al. 2006

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Study design: Cross-over study. Objective: To determine the effect of strenuous wheelchair exercise on oxygen uptake ( . VO 2 ), muscle activity and propulsion cycle timing (including the push time and recovery time during one full arm cycle). Setting: Laboratory of Sport Sciences at the University of France-Comte in France. Methods: Two exercise bouts of 6-min duration were performed at a constant workload:(1) non-fatigable exercise (moderate workload) and (2) fatigable exercise (heavy workload). Measurement of .VO 2 , surface electromyographic activity (EMG) from shoulder muscles, and temporal parameters of wheelchair ergometer propulsion were collected from eight able-bodied men (2674 years). Results: A progressive increase in .VO 2 associated with EMG alterations (Po0.05), and a decrease of the cycle and recovery time (Po0.05) during the heavy exercise. Whereas the push time remained constant, an increased muscle activation time (Po0.05) was found during heavy exercise. Conclusion: Observations during wheelchair ergometry indicate the development of fatigue and inefficient muscle coordination, which may contribute to deleterious stress distributions at the shoulder joint, increasing susceptibility to injury.

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

Cited by 374 publications

References 0 publications

Respiratory muscles and weaning failure

Respiratory muscles and weaning failure

Localized muscle fatigue: review of three experiments

Changes in oxygen uptake, shoulder muscles activity, and propulsion cycle timing during strenuous wheelchair exercise

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