Effects of muscle fiber type and size on EMG median frequency and conduction velocity

Kupa, E. J.; Roy, Serge H.; Kandarian, Susan C.; Luca, Carlo J. De

doi:10.1152/jappl.1995.79.1.23

Cited by 384 publications

(331 citation statements)

References 18 publications

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“…In normal 21 conditions, during sustained voluntary contractions MFCV gradually declines, which 22 is related to modifications in muscle membrane excitability (Chisari et al 1998). The 23 time course of this MFCV decline has been shown to be higher in muscles with a 24 higher proportion of type II muscle fibers (Kupa et al 1995). Taken together, these 25 findings of a higher fatigability and MFCV slope in T2D appears to support the 26 previously reported shift in muscle fiber type composition with diabetes, with a 27 higher proportion of fast-twitch fibers at the expenses of slow-twitch ones (Saltin et 28 al.…”

Section: Muscle Fatigue 10mentioning

confidence: 99%

Effect of exercise training on neuromuscular function of elbow flexors and knee extensors of type 2 diabetic patients

Bazzucchi

Vito

Felici

et al. 2015

Journal of Electromyography and Kinesiology

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Massimo (2015) Effect of exercise training on neuromuscular function of elbow flexors and knee extensors of type 2 diabetic patients. Journal of Electromyography and Kinesiology, 25 (5). pp. 815-823.Downloaded from: http://insight.cumbria.ac.uk/2048/ Usage of any items from the University of Cumbria's institutional repository 'Insight' must conform to the following fair usage guidelines.Any item and its associated metadata held in the University of Cumbria's institutional repository Insight (unless stated otherwise on the metadata record) may be copied, displayed or performed, and stored in line with the JISC fair dealing guidelines (available here) for educational and not-for-profit activities provided that• the authors, title and full bibliographic details of the item are cited clearly when any part of the work is referred to verbally or in the written form• a hyperlink/URL to the original Insight record of that item is included in any citations of the work • the content is not changed in any way• all files required for usage of the item are kept together with the main item file. You may not• sell any part of an item• refer to any part of an item without citation • amend any item or contextualise it in a way that will impugn the creator's reputation• remove or alter the copyright statement on an item.The full policy can be found here. Alternatively contact the University of Cumbria Repository Editor by emailing insight@cumbria.ac.uk. Accepted Manuscript

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Section: Muscle Fatigue 10mentioning

confidence: 99%

Effect of exercise training on neuromuscular function of elbow flexors and knee extensors of type 2 diabetic patients

Bazzucchi

Vito

Felici

et al. 2015

Journal of Electromyography and Kinesiology

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“…to data obtained from voluntary contractions require the consideration of several secondary but not unimportant factors" (23). These factors, which are common to other animal studies (17,28), include differences between electrically evoked EMG signals and those detected during voluntary contractions, intramuscular (or over the muscle fascia) and surface recordings, and recordings of activity by discrete and mixed populations of muscle fiber types.…”

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confidence: 99%

Counterpoint: Spectral properties of the surface emg do not provide information about motor unit recruitment and muscle fiber type

Farina

2008

Journal of Applied Physiology

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The surface electromyogram (EMG) comprises the sum of the electrical contributions made by the active motor units to the interference signal detected by electrodes placed on the skin overlying the muscle. Because it provides a global measure of motor unit activity, this signal is a valuable tool for assessing the level of muscle activation.The analysis of the surface EMG in the frequency domain has been used in some instances, such as fatiguing contractions, to provide an indirect measure of the relative changes in average muscle fiber conduction velocity (19) or in the profile of the intracellular action potential (6). In addition to these applications, the spectral characteristics of the surface EMG have been used to infer motor unit recruitment strategies and the fiber-type composition of a muscle. Higher characteristic spectral frequencies are associated with a greater proportion of type II fibers (20, 21) and changes in EMG spectral variables are used to infer the recruitment of faster or slower motor units (3,26).The capacity of surface EMG spectral properties to provide information about motor unit recruitment or the proportion of fiber types is based on the rationale that higher threshold (and type II) motor units produce surface action potentials with larger relative energy at higher frequencies than lower threshold (and type I) motor units.Because in these applications the main determinant of the frequency content of an action potential is assumed to be its conduction velocity (28), the crucial issue in this debate is the validity of two assumptions: 1) average conduction velocity of the active motor units is related to fiber-type proportions, and 2) changes in the spectral properties of the surface EMG are associated with changes in average conduction velocity.Fiber-type composition and average muscle fiber conduction velocity. There are several physiological details that confound this association. First, the two main fiber types do not have distinct conduction velocities in humans, but rather conduction velocity has a continuous distribution with a single peak (25). Second, average conduction velocity of muscle fiber action potentials can differ among populations of motor units due to differences in fiber diameter and independent of changes in fiber-type proportions (4). Third, the number of muscle fibers innervated by a motor unit has a skewed distribution. For example, the first dorsal interosseus muscle comprises an equal number of type I and II fibers, but ϳ84% of the motor units have slow contraction times and are fatigue resistant (7). Fourth, the conduction velocity of muscle fiber action potentials can change by ϳ20% with variation in discharge rate (24) and the range of discharge rates varies with recruitment threshold in a population of motor units (2). Fifth, the conduction velocity of muscle fiber action potentials varies with fiber length (15).Experimental evidence: fiber-type composition vs. muscle fiber conduction velocity. The significance of the physiological limitations discussed in...

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“…14 In particular, as might be expected, muscles with a greater percentage of fast glycolytic and fast oxidative glycolytic fibers exhibit a more rapid reduction of MF over the course of a contraction than those with a higher concentration of Type II fibers. Thus, the slower rates of decline in the slopes of MF and MPF that we found in the marathon athletes support the ideas that fiber-type composition can be predicted on the basis of MF and that the arm muscles of wheelchair marathon racers have gained a higher predominance of red muscle fibers.…”

Section: Discussionmentioning

confidence: 71%

Muscle endurance and power spectrum of the triceps brachii in wheelchair marathon racers with paraplegia

et al. 2003

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Objective: To investigate differences in triceps brachii endurance and electrical activity between elite marathon and recreational wheelchair athletes with paraplegia. Design and methods: Nine male elite wheelchair athletes between 20 and 46 years of age (average 29.078.2 years) with complete (ASIA-A) T4-L1 paraplegia were compared to a group of six male height-and weight-matched recreational wheelchair athletes with similar ages and injuries. Right triceps brachii maximum voluntary contraction (MVC), as well as the duration of the ability to maintain a 50% MVC were determined for all subjects. Median frequency (MF) and mean power frequency (MPF) were evaluated with fast Fourier transform spectrum analysis. MF and MPF rates of change were calculated and compared with the Student's t-test. Setting: Department of Rehabilitation Medicine, University of Occupational and Environmental Health, Japan. Results: Right triceps brachii MVCs of the marathoners (42.478.8 N m (range 33-55 N m)) and recreational athletes (41.679.3 N m (range 32-56 N m)) did not differ significantly (P ¼ 0.63). Endurance, however, did. All of the athletes, but none of the control subjects, were able to maintain a 50% MVC contraction of the right triceps brachii for 2 min (the average contraction duration in the latter group was 75.5716.2 s). MF and MPF of the triceps brachii decreased linearly in both groups, but the slopes in the marathoners (À8.974.6 (À3.8 to À16.4) and À9.774.6 (À4.0 to À17.2)%/min, respectively) were statistically less steep than those in the recreational athletes (À22.378.2 (À9.6 to À31.4) and À21.276.4 (À11.4 to À28.6)%/min, respectively). Conclusion: Elite marathoners and active wheelchair users have similar triceps brachii strength. The marathoner's triceps brachii, however, display a significantly improved endurance and a slower decline of MF and MPF with time than do those of their recreational athlete control group.

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Effects of muscle fiber type and size on EMG median frequency and conduction velocity

Cited by 384 publications

References 18 publications

Effect of exercise training on neuromuscular function of elbow flexors and knee extensors of type 2 diabetic patients

Effect of exercise training on neuromuscular function of elbow flexors and knee extensors of type 2 diabetic patients

Counterpoint: Spectral properties of the surface emg do not provide information about motor unit recruitment and muscle fiber type

Muscle endurance and power spectrum of the triceps brachii in wheelchair marathon racers with paraplegia

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