Reliability of mechanomyographic amplitude and mean power frequency during isometric step and ramp muscle actions

doi:10.1016/j.jneumeth.2008.02.017

Journal of Neuroscience Methods

Volume 171, Issue 1, 15 June 2008, Pages 104-109

https://doi.org/10.1016/j.jneumeth.2008.02.017 Get rights and content

Abstract

This study examined the reliability of mechanomyographic amplitude (MMG_RMS) and mean power frequency (MMG_MPF) for the vastus lateralis during isometric maximal voluntary contractions (MVCs) and submaximal step and ramp muscle actions of the leg extensors. Nineteen participants (mean ± S.D. age = 24 ± 4 yrs) performed two isometric MVCs, 10 randomly ordered isometric step muscle actions at 5, 15, 25, 35, 45, 55, 65, 75, 85, and 95% of MVC, and two 6 s isometric ramp muscle actions during 3 trials separated by 3–5 days. The intraclass correlation coefficient (ICC), standard error of the measurement (SEM), and minimal difference (MD) were used for test–retest reliability, while repeated measures ANOVAs were used to quantify systematic variability. Systematic variability was only present across the 3 trials at 5% MVC during the step muscle action for MMG_RMS and at 35% of MVC during the ramp muscle action for MMG_MPF. The ICCs ranged from 0.39 to 0.89 and 0.36 to 0.80, while the SEM (% of mean) ranged from 14.9 to 33.9% and 6.9 to18.9% for MMG_RMS and MMG_MPF, respectively. Thus, MMG_RMS and MMG_MPF demonstrated reliability that was comparable to that of the surface electromyographic signal.

Introduction

The reliability of a measurement refers to the consistency of a test over a certain number of trials. Often, the relative consistency of a measurement is quantified using reliability coefficients called intraclass correlation coefficients (ICCs) (Streiner and Norman, 1995). Relative reliability refers to the consistency of the position or rank of individuals in the group relative to others. The ICC is unitless, and can “theoretically vary between 0 and 1.0, where an ICC of 0 indicates no reliability and an ICC of 1.0 indicates perfect reliability (Weir, 2005).” Another common reliability measure is the standard error of the measurement (SEM), which provides an absolute index of reliability. Absolute reliability refers to the consistency of scores of individuals. The SEM gives an indication on the precision of the measurement and, therefore, can provide an index of the expected trial-to-trial noise for the variable being examined (Weir, 2005). In addition, the minimal difference (MD) is derived from the SEM and indicates the minimum difference needed between the trials to be considered real (Weir, 2005). Collectively, these measures provide a comprehensive assessment of reliability.

Surface mechanomyography (MMG) has become a fairly common technique for examining muscle function in the movement sciences. Despite the growth in MMG research in recent years, however, there is relatively little known regarding the reliability of the MMG signal. For example, previous investigations have reported reliability coefficients ranging from 0.94 to 0.98 and 0.72 to 0.82 for MMG amplitude (MMG_RMS) and mean power frequency (MMG_MPF), respectively (Smith et al., 1997, Cramer et al., 2002, Ebersole et al., 2002). In addition, Akataki et al. (1999) examined the reliability of MMG_RMS for the biceps brachii during submaximal isometric step muscle actions of the forearm flexors at 10–90% at of the maximal voluntary contraction (MVC). However, the authors (Akataki et al., 1999) reported only the average ICC across all percents of the MVC (ICC = 0.83) for MMG_RMS, and the frequency component of the MMG signal was not examined. Given that the literature on the reliability of the MMG signal has focused mainly on ICCs, without assessing the SEM and MD, additional studies are needed to examine the reliability of the MMG signal in a more comprehensive manner. Therefore, the purpose of this investigation was to use the ICC, SEM and MD to examine the reliability of MMG_RMS and MMG_MPF from the vastus lateralis during isometric MVCs and submaximal step and ramp muscle actions of the leg extensors.

Section snippets

Subjects

Nineteen healthy men (mean ± S.D. age = 24 ± 4 yrs; stature = 173 ± 9 cm; mass = 75 ± 13 kg) volunteered for this investigation. None of them reported any current or ongoing neuromuscular diseases or musculoskeletal injuries that involved the ankle, knee, or hip joints. This study was approved by the University of Oklahoma Institutional Review Board. All participants read and signed an informed consent form and completed a Pre-Exercise Testing Health & Exercise Status Questionnaire.

Research design

Isometric torque for the

Results

The reliability and measurement variability statistics for isometric torque, MMG_RMS, and MMG_MPF during the step and ramp muscle actions are presented in Table 1. Table 2 contains the same statistics for the MVCs, which were common to both the step and ramp muscle actions.

Discussion

In the present investigation, the ICCs ranged from 0.39 to 0.89 and 0.36 to 0.80 for MMG_RMS and MMG_MPF, respectively (Fig. 2). Systematic variability was present at 5% of MVC during the step muscle action for MMG_RMS (P = 0.012) and at 35% of MVC during the ramp muscle action for MMG_MPF (P = 0.044). For MMG_RMS, the highest ICCs were recorded during muscle actions equal to or greater than 35% of MVC (ICC > 0.70), except for the ramp muscle action at 55% of MVC (ICC = 0.67). The lowest ICCs occurred at

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Both EMG and MMG amplitude in the RF muscle were found to be smaller in step contraction than in ramp increasing, which was consistent with results from the plantar flexors in studies performed by Bilodeau et al. [86] and Ryan et al. [28]. However, in a departure from previous studies examining the EMG and MMG performance in step vs. ramp increasing contractions [25,32,35,87,88], the present study also investigated the EMG and MMG amplitude in ramp decreasing contractions in order to comprehensively compare all of the movement protocols that may be used in muscle training or rehabilitation. We found that the EMG RMS of ramp decreasing contractions was significantly smaller than that of ramp increasing and bigger than that of the step test.
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Reliability of mechanomyographic amplitude and mean power frequency during isometric step and ramp muscle actions

Abstract

Introduction

Section snippets

Subjects

Research design

Results

Discussion

J Electromyogr Kinesiol

Int J Biomed Comput

J Neurosci Methods

J Electromyogr Kinesiol

Repeatability study of mechanomyography in submaximal isometric contractions using coefficient of variation and intraclass correlation coefficient

Electromyogr Clin Neurophysiol

Mechanomyogram and force relationship during voluntary isometric ramp contractions of the biceps brachii muscle

Eur J Appl Physiol

Comparison of Fourier and wavelet transform procedures for examining mechanomyographic and electromyographic frequency versus isokinetic torque relationships

Electromyogr Clin Neurophysiol

Analysis of myoelectric signals recorded during dynamic contractions

IEEE Eng Med Biol Mag

Power output, mechanomyographic, and electromyographic responses to maximal, concentric, isokinetic muscle actions in men and women

J Strength Cond Res

Mechanomyographic and electromyographic responses to unilateral isometric training

J Strength Cond Res

Measures of reliability in sports medicine and science

Sports Med