Reproducibility of surface EMG during dynamic shoulder forward flexions: a study of clinically healthy subjects

Abstract

There is a shortage of studies concerning the reproducibility of surface electromyography (EMG) during dynamic contractions. The movement per se introduces factors that could have the potential to affect the characteristics of the electromyogram. The aim of this study was to investigate the during-the-day reproducibility (using intra-class coefficient, ICC) of the peak torque (PT) and the EMG variables (without removing electrodes) of dynamic shoulder forward flexions. Eleven healthy women performed three sets of 10 dynamic maximum right-shoulder flexions at 1 h intervals using an isokinetic dynamometer. The PT of each flexion was determined. EMG signals were recorded from four muscles (trapezius, deltoid, infraspinatus and biceps brachii) using surface electrodes, and the mean frequency of the power spectrum (MNF [Hz]) and the signal amplitude (RMS [microV]), were computed. The ability to relax between maximum flexions was calculated as a ratio between the RMS during the passive extension phase and the RMS during the active flexion phase of each contraction cycle. This ratio is the signal amplitude ratio (SAR). The present study showed good reproducibility for PT, MNF and RMS, while the reproducibility of SAR was generally acceptable (fair) according to the criteria used.

Reliability of telemetric electromyography and near-infrared spectroscopy during high-intensity resistance exercise

“…While these findings are similar to previous research reporting intra-test ICC values for mean RMS and frequency during single-joint isokinetic tests (Larsson et al, 1999a;Larsson et al, 1999b), these previous investigations have demonstrated a smaller range of ICC values than the current study. While this may indicate greater variability in the current study, caution should be taken when comparing ICC values between separate investigations, as this statistic is largely influenced by the range of data scores and the population studied (Atkinson and Nevill, 1998).…”

“…At present, it is difficult to determine the cause of the varied reliability within certain sets, as no clear relationships are evident between the level of reliability and either the number of repetitions performed in a set, nor the intensity of the set. It is possible that the small sample size employed, although similar to previous investigations that have assessed EMG reliability (Larsson et al, 1999a;Larsson et al, 1999b), may have contributed to these findings.…”

“…Past studies have been limited to isokinetic dynamometry of single-joint exercises (Larsson et al, 1999a;Larsson et al, 1999b). As such, a back squat variation was employed in the current study to analyse multi-joint isotonic resistance exercise.…”

“…While the sample size used in this research is similar to previous investigations that have examined the reproducibility of EMG and NIRS measures during dynamic resistance exercise (Larsson et al, 1999a;Larsson et al, 1999b;Pereira et al, 2005), it is possible that a larger sample size may have provided less variance in mean reliability results. Nonetheless, we recruited well-trained young men only in an attempt to investigate a homogenous subject group, with respect to repeated resistance exercise performance.…”

Reliability of EMG activity in complete denture users during simulation of activities of daily living

“…Previous kinesiologic EMG studies reported samples composed by six to thirteen subjects tested to reach objects, lift box, and flexion shoulder, obtaining good reprodutibility of results (22)(23)(24)(25). This is the first study to use kinesiologic EMG to evaluate the effect of occlusal support on masticatory, head and neck, trunk, and lower limb muscles simultaneously during complex functional tasks.…”