Global electromyographic signal characteristics depend on maximal isometric contraction method in the knee extensors

Tomko, Patrick M.; Colquhoun, Ryan J.; Magrini, Mitchel A.; Muddle, Tyler W.D.; Jenkins, Nathaniel D.M.

doi:10.1016/j.jelekin.2018.07.002

Cited by 10 publications

(24 citation statements)

References 30 publications

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“… 12 , 13 In contrast, others analyse percentage amplitudes (normalised to an individual reference value, e.g. MVC) 12 , 15 , 32 Although the normalisation procedure is recommended in studies using sEMG, 10 , 40 , 41 should be borne in mind that when applying normalization information regarding the level of innervation is lost, the resulting percentage value ( e.g. 50%) in a healthy person and an MS patient may be the same.…”

Section: Discussionmentioning

confidence: 99%

“… 5 The surface EMG signal represents the summation of the electrical activity of active motor units within the recording area of the surface electrodes placed over a muscle of interest and is often referred to as a global measure of motor unit (MU) activity. 10 In healthy subjects during sustained submaximal static contractions, notable changes occur as the signal amplitude (RMS) increases and a shift in the EMG spectrum toward lower frequencies occurs. Both parameters are used as markers of muscle fatigue.…”

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confidence: 99%

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Assessment of muscle fatigue in multiple sclerosis patients in electromyographic examinations

Radecka¹,

Knyszyńska²,

Lubkowska³

2023

Eur J Phys Rehabil Med

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BACKGROUND Although surface electromyography (sEMG) is the method used to assess muscle fatigue in patients with multiple sclerosis (PwMS), no pattern of signal change has been established. The differences shown in the parameters of other neurophysiological tests between PwMS and control groups (CG) suggest the differentiation of the sEMG signal. AIM The purpose of the study was to verify potential differences in the fatigue sEMG signal in PwMS compared to CG. DESIGN Cross-sectional study. SETTING Chair and Department of Functional Diagnostics and Physical Medicine. POPULATION A randomised group of patients diagnosed with MS (30, 20-41 years). A random sample of young, healthy adults (median 28, 20-39 years). METHODS Measurement of sEMG was performed from extensor carpi radialis (ECR) and FCR (flexor carpi radialis) during 60-80% of maximum voluntary contraction (MVC) of extension and then flexion for 60sec, accordance with the fatigue protocol in Research XP Master Edition software (v. 1.08.27). RESULTS Root mean square amplitude (A RMS ) were lower for muscle in the PwMS compared to the CG (ECR P=0.0001, FCU P<0.0001). In the CG, the A RMS value increases during fatigue contraction (ECR P=0.0003, FCU P<0.0001), while in the PwMS) the A RMS value decreases (ECR: P<0.0001, FCU P<0.0001. CONCLUSIONS The PwMS show an opposite pattern of preservation of the absolute value of A RMS during prolonged contraction to fatigue, compared with healthy subjects. CLINICAL REHABILITATION IMPACT The results are important for clinical trials using sEMG to assess fatigue in PwMS. Knowledge of the differences in the time domain changes in sEMG signal between healthy subjects and PwMS is crucial for correctly interpreting the results.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Assessment of muscle fatigue in multiple sclerosis patients in electromyographic examinations

Radecka¹,

Knyszyńska²,

Lubkowska³

2023

Eur J Phys Rehabil Med

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“…Visits 2 and 3 served as experimental visits in which data were collected and analyzed. As warm-up, participants performed two to three submaximal warm-up contractions each at~25, 50, and 75% of their perceived best effort (Tomko et al 2018). Following the warmup, participants then performed two MVIC attempts, during which they were instructed to kick out "as hard as possible" for~5 s. Ninety seconds of rest were given between each attempt to limit fatigue.…”

Section: Methodsmentioning

confidence: 99%

The influence of input excitation on the inter- and intra-day reliability of the motor unit firing rate versus recruitment threshold relationship

Colquhoun

Tomko

Magrini

et al. 2018

Journal of Neurophysiology

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Decomposition of the surface electromyographic (sEMG) signal is commonly used to examine motor unit (MU) firing behavior. However, the intra- and inter-day reliability of these measurements has yet to be quantified or reported. This investigation 1) examined the effect of input excitation on the mean firing rate (MFR) vs. recruitment threshold (RT) relationship and 2) determined the inter- and intra-day reliability of the MFR vs. RT relationship at 30%, 50%, and 70% of maximum voluntary isometric strength (MVIC). Twenty-eight healthy males (23 ± 3 yr) completed two experimental visits, during which they performed MVIC testing and isometric ramp contractions at 30%, 50%, and 70% MVIC. sEMG signals were recorded from the vastus lateralis during the ramp contractions and decomposed to establish the MFR vs. RT relationship for the detected MUs. Intra- and inter-day reliability was then established for the slopes and y-intercepts of the MFR vs. RT relationship at each contraction intensity. All participants displayed significant MFR vs. RT relationships ( r range: −0.662 to −0.999; P ≤ 0.001–0.006). Intra- and inter-day intraclass correlation coefficients (ICCs) ranged from 0.766–0.824 and 0.867–0.919 for the slopes and from 0.780–0.915 and 0.804–0.927 for the y-intercepts, respectively. Furthermore, the slope coefficient was significantly greater at 70% than at 30% MVIC, and the y-intercepts increased with increasing contraction intensities. Changes in input excitation to the MU pool alter the magnitude, but not the reliability, of the slopes and y-intercepts of the MFR vs. RT relationship. NEW & NOTEWORTHY The firing behavior of the motor unit (MU) pool is often characterized using the mean firing rate vs. recruitment threshold relationship of the active MUs. Although this relationship has been widely used, this is the first study to report the effects of input excitation (contraction intensity) on the intra- and inter-day reliability of this relationship. The criteria used for MU analysis and the model utilized in this study allow for generalization to outside investigators and laboratories.

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“…After each warm-up isometric muscle contraction, the patients completed five sec maximal Follow-up Analysis isometric leg (e.g., knee extension, knee flexion, ankle dorsiflexion, and plantar flexion, respectively) three times with one min of rest between the attempts to avoid fatigue. [30] The mean value was calculated, and EMG data were excluded for one sec before and one sec after the completion of each attempt.…”

Section: Outcome Measuresmentioning

confidence: 99%

Lower limb muscle activities and gain in balancing ability following two types of stair gait intervention in adult post-chronic stroke patients: A preliminary, randomized-controlled study

Choi

Kim

Lee³

et al. 2020

Turk J Phys Med Rehab

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Global electromyographic signal characteristics depend on maximal isometric contraction method in the knee extensors

Cited by 10 publications

References 30 publications

Assessment of muscle fatigue in multiple sclerosis patients in electromyographic examinations

Assessment of muscle fatigue in multiple sclerosis patients in electromyographic examinations

The influence of input excitation on the inter- and intra-day reliability of the motor unit firing rate versus recruitment threshold relationship

Lower limb muscle activities and gain in balancing ability following two types of stair gait intervention in adult post-chronic stroke patients: A preliminary, randomized-controlled study

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