Continuous monitoring of electromyography (EMG), mechanomyography (MMG), sonomyography (SMG) and torque output during ramp and step isometric contractions

Abstract

In this study we simultaneously collected ultrasound images, EMG, MMG from the rectus femoris (RF) muscle and torque signal from the leg extensor muscle group of nine male subjects (mean±SD, age=30.7±.4.9 years; body weight=67.0±8.4kg; height=170.4±6.9cm) during step, ramp increasing, and decreasing at three different rates (50%, 25% and 17% MVC/s). The muscle architectural parameters extracted from ultrasound imaging, which reflect muscle contractions, were defined as sonomyography (SMG) in this study. The cross-sectional area (CSA) and aspect ratio between muscle width and thickness (width/thickness) were extracted from ultrasound images. The results showed that the CSA of RF muscles decreased by 7.25±4.07% when muscle torque output changed from 0% to 90% MVC, and the aspect ratio decreased by 41.66±7.96%. The muscle contraction level and SMG data were strongly correlated (R(2)=0.961, P=0.003, for CSA and R(2)=0.999, P<0.001, for width/thickness ratio). The data indicated a significant difference (P<0.05) in percentage changes for CSA and aspect ratio among step, ramp increasing, and decreasing contractions. The normalized EMG RMS in ramp increasing was 8.25±4.00% higher than step (P=0.002). The normalized MMG RMS of step contraction was significantly lower than ramp increasing and decreasing, with averaged differences of 12.22±3.37% (P=0.001) and 12.06±3.37% (P=0.001), respectively. The results of this study demonstrated that the CSA and aspect ratio, i.e., SMG signals, can provide useful information about muscle contractions. They may therefore complement EMG and MMG for studying muscle activation strategies under different conditions.

A novel approach for detection of muscle boundary in ultrasound images

“…In both studies, the CSA values showed an initial small increase followed by a curvilinear decrease with the increase of torque. The findings on CSA in the present study are also in accordance with our previous study [10], which measured isometric ramp contraction but the CSA values at separate contraction levels were calculated manually. Comparing the relationship curves of both studies, the findings of present study demonstrated more information: 1) the initial increase of CSA can not be observed in previous study because it occurred below the first contraction level; and 2) the reliability of the polynomial regression was improved since there were much more sample points in the present study.…”

Human muscle fascicle behavior in agonist and antagonist isometric contractions

“…Finally, data from the literature indicate that EMG activity recorded during submaximal isometric contractions, performed at a similar rate to that of this protocol (20% MVC/s), does not differ significantly from EMG signals acquired during step contractions. 33,34 This suggests that direct EMG comparisons can be done between both protocols. 35 Joint Motion.…”

Monitoring Changes of the Tibialis Anterior during Dorsiflexion with Electromyography, Sonomyography, Dynamometry and Kinematic Signals

“…Other authors have focused on the role of ADL in the upper limb (5,14,15). The lower limb is also widely studied, mainly due to its relevance in human gait (16,17).…”