Assessment of Quadriceps Contraction Using a Novel Surface Mechanomyography Sensor During a Neuromuscular Control Screening Task

PURPOSE Neuromuscular control is an important factor for injury incidence and post‐surgical rehabilitation. Surface Mechanomyography (sMMG) sensors are novel wearable devices that are applied over a muscle group to measure the physical output of muscle deformation resulting from a muscle contraction. Electromyography (EMG) is the clinical standard for assessing the electrical signal identifying muscle activation. However, well‐established data collection and analysis challenges limit the utility of EMG for wide‐spread neuromuscular control screening in a clinic environment. The purpose of this study was to investigate the ability of sMMG sensors to detect timing patterns of muscle contraction and compare time events to those collected through traditional clinical EMG during a bilateral squat task. METHODS Eleven healthy, active individuals (mean age= 30.0 ± 10.77 y, 7 males, 4 females) underwent a neuromuscular control assessment with EMG and sMMG sensors simultaneously applied to the right quadriceps. Subjects performed a series of 3 bilateral deep squats. EMG data processed with a low‐pass 6 th order Butterworth filter and a TKEO function, and raw sMMG data were used for timing analyses. Statistical analyses included paired T‐test assessments between measurement modalities. RESULTS There was no significant difference in the timing of total duration of quadriceps contraction between EMG (mean= 2.526 ± 0.553 s) and sMMG (mean= 2.527 ± 0.539 s), p= 0.985. The duration of quadriceps contraction during the descent phase of the squat (eccentric contraction, p= 0.773) and the ascent phase (concentric contraction, p= 0.298) did not differ significantly between modalities. CONCLUSIONS Results are consistent with physiologic expectations that myoelectrical activity (measured by EMG) and the physical muscle deformation of muscles (measured by sMMG) occur in extremely rapid succession. Successful sMMG detection of quadriceps contraction is supported by similarity to EMG time signatures. Findings also suggest the ability of sMMG sensors to detect timing of activation for different types of muscle contraction during a functional exercise without the need for complex signal processing (Figure 1). The sMMG sensor may be helpful for assessing quadriceps muscle performance and timing as part of quick, in‐the‐clinic neuromuscular control screenings for injury prevention, rehabilitation, and exercise training.Example of data analysis steps for comparison between electromyography (EMG) and surface mechanography (sMMG) timing during a bilateral squat task