Effects of eccentric exercise on trunk extensor torque and lumbar paraspinal EMG

Hermann, Karl M.; Barnes, William S.

doi:10.1097/00005768-200106000-00017

Cited by 23 publications

(21 citation statements)

References 32 publications

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“…If the trunk velocity and acceleration during the eccentric portion of the exercise had been equal to the trunk velocity and acceleration during the concentric portion of the exercise, we would have likely observed even lower RMS-EMG values during the eccentric portion of the exercise than the ones observed in the study herein described. These observations appear to be consistent with previous studies showing smaller RMS-SEMG values for eccentric contractions compared to concentric contractions (Bigland-Ritchie and Woods, 1976; Hermann and Barnes, 2001), as well as with studies showing that lower MU firing rates mark eccentric contractions compared to concentric contractions (Duchateau and Enoka, 2008; Kallio et al, 2013). This suggests that differences in excitatory drive as well as in the excitability of the motor neuron pool to the back extensor muscles mark eccentric vs. concentric contractions.…”

Section: Discussionsupporting

confidence: 92%

Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

et al. 2017

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Purpose: To investigate the differences in neural control of back muscles activated during the eccentric vs. the concentric portions of a cyclic, submaximal, fatiguing trunk extension exercise via the analysis of amplitude and time-frequency parameters derived from surface electromyographic (SEMG) data.Methods: Using back dynamometers, 87 healthy volunteers performed three maximum voluntary isometric trunk extensions (MVC's), an isometric trunk extension at 80% MVC, and 25 cyclic, dynamic trunk extensions at 50% MVC. Dynamic testing was performed with the trunk angular displacement ranging from 0° to 40° and the trunk angular velocity set at 20°/s. SEMG data was recorded bilaterally from the iliocostalis lumborum at L1, the longissimus dorsi at L2, and the multifidus muscles at L5. The initial value and slope of the root mean square (RMS-SEMG) and the instantaneous median frequency (IMDF-SEMG) estimates derived from the SEMG recorded during each exercise cycle were used to investigate the differences in MU control marking the eccentric vs. the concentric portions of the exercise.Results: During the concentric portions of the exercise, the initial RMS-SEMG values were almost twice those observed during the eccentric portions of the exercise. The RMS-SEMG values generally increased during the concentric portions of the exercise while they mostly remained unchanged during the eccentric portions of the exercise with significant differences between contraction types. Neither the initial IMDF-SEMG values nor the time-course of the IMDF-SEMG values significantly differed between the eccentric and the concentric portions of the exercise.Conclusions: The comparison of the investigated SEMG parameters revealed distinct neural control strategies during the eccentric vs. the concentric portions of the cyclic exercise. We explain these differences by relying upon the principles of orderly recruitment and common drive governing motor unit behavior.

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Section: Discussionsupporting

confidence: 92%

Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

et al. 2017

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“…Electrodes were placed over the left LLES 2 cm lateral to the L5-S1 spinous processes and over the left ULES 6 cm lateral to the L1-L2 spinous processes. While a number of studies have used the L5/S1 configuration of surface EMG electrodes for examination of multifidus (Hermann and Barnes 2001;Vezina and Hubley-Kozey 2000), others suggest the intramuscular needle electrodes are necessary for accurate assessment (Stokes et al 2003). For the present study, the EMG activity collected by the electrode arrangement is referred to as LLES as it is expected that activity from more than just the multifidus would be present.…”

Section: Electromyography (Emg)mentioning

confidence: 99%

An inverted seated posture decreases elbow flexion force and muscle activation

2009

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The purpose of this study was to determine if discrepancies exist between upright and inverted seated positions in isometric maximal voluntary contraction (MVC) elbow flexor force, MVC force produced in the first 100 ms (F100), MVC rate of force development, electromyographic (EMG) activity of the biceps and triceps as well as heart rate and blood pressure. The results showed significantly (p < 0.01) higher MVC force (543.6 +/- 29.6 vs. 486.5 +/- 23.0 N), F100 (328.3 +/- 94.5 vs. 274.6 +/- 101.8 N), rate of force development (p = 0.003) (1,851.9 +/- 742.2 vs. 1,591.0 +/- 719.6 N s(-1)) and biceps brachii EMG activity (48%, p < 0.01) in the upright versus inverted condition. There were relatively greater co-contractions with the inverted position (p < 0.01) due to the lack of change in triceps' EMG and the substantial decrease in biceps' EMG. There were no significant changes in trunk EMG activity. With inversion, there were significant decreases in heart rate (16.8%), systolic (11.6%) and diastolic (12.1%) blood pressures (p < 0.0001). These results illustrate decrements in neuromuscular performance with an inverted seated posture which may be related to an altered sympathetic response.

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“…The effects of fatigue are temporary as muscles recover from the requirements of the task over a relatively short period (Hermann and Barnes, 2000;Kuorinka, 1988;Mannion and Dolan, 1994;Potvin and Norman, 1993). Frequent breaks and extended rest periods are common strategies used to reduce the effects of fatigue in the workplace suggesting that muscle fatigue may only be a minor factor in considering low back injuries.…”

Section: Introductionmentioning

confidence: 99%

Interaction of viscoelastic tissue compliance with lumbar muscles during passive cyclic flexion–extension

Olson

Solomonow

2009

Journal of Electromyography and Kinesiology

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Effects of eccentric exercise on trunk extensor torque and lumbar paraspinal EMG

Cited by 23 publications

References 32 publications

Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

An inverted seated posture decreases elbow flexion force and muscle activation

Interaction of viscoelastic tissue compliance with lumbar muscles during passive cyclic flexion–extension

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