Trunk motor variability in patients with non-specific chronic low back pain

Abstract

Muscle recruitment is altered in patients with chronic LBP in the presence of muscle fatigue. Consequently, these patients exhibit changes in muscle recruitment pattern and intensity (lower levels of motor variability) during sustained isometric contraction that may be attributed to variation in the control of motor units within and between muscles. However, patients with LBP are able to increase their motor variability over time but with a lower increase compared to healthy participants.

Test-Retest Reliability of Trunk Motor Variability Measured By Large-Array Surface Electromyography

“…Both of these variables, especially the centroid, were extensively used in fundamental EMG researches. 2,5,7,18,19 However, this study is the first one that analyzed the reliability of these variables. The dispersion variable representing the area of the centroid's displacement for each phase showed moderate to strong correlations at the beginning (P1) and during the later stages of muscle fatigue (P4, P5) and very strong correlations at the exhaustion phase (P6).…”

“…As described in a previous study, 13 dispersion was obtained by calculating the center of gravity dispersion in 6 equal and consecutive time periods during the Sorensen test of a given subject. 7 The displacement of the centroid in x-and y-axis was also separated in 6 time periods. To confirm muscular fatigue in both groups, mean normalized slopes of the median frequency (MDF) for each electrodes were calculated.…”

“…Using large-array surface electromyography (sEMG) to document the topographical representation of muscle activation, 4 several investigators have revisited the muscle recruitment changes associated to lower back muscle fatigue. [5][6][7] In short, the use of large-array sEMG has enabled the identification of distinctive neuromuscular patterns such as the redistribution of muscle activity in the presence of muscle fatigue and an increase in motor variability. 7 Moreover, even though muscle fatigue leads to increases in motor variability in both patients with chronic low back pain (LBP) and asymptomatic participants, motor variability remains lower in patients with chronic LBP.…”

“…[5][6][7] In short, the use of large-array sEMG has enabled the identification of distinctive neuromuscular patterns such as the redistribution of muscle activity in the presence of muscle fatigue and an increase in motor variability. 7 Moreover, even though muscle fatigue leads to increases in motor variability in both patients with chronic low back pain (LBP) and asymptomatic participants, motor variability remains lower in patients with chronic LBP. 7 Although these results may suggest that motor variability plays a role in LBP development, there are still several steps needed before any large-array sEMG assessment can be recommended in the investigation of neuromuscular control in clinical populations.…”

“…7 Moreover, even though muscle fatigue leads to increases in motor variability in both patients with chronic low back pain (LBP) and asymptomatic participants, motor variability remains lower in patients with chronic LBP. 7 Although these results may suggest that motor variability plays a role in LBP development, there are still several steps needed before any large-array sEMG assessment can be recommended in the investigation of neuromuscular control in clinical populations. Indeed, although many clinical interventions and rehabilitation programs have targeted changes in motor control over the past decade, very few EMG-based variables have undergone in-depth validation.…”