The Effects of Pain and a Sensorimotor Control Strategy on Neuromuscular and Kinetic Characteristics in Individuals with Chronic Non-Specific Low-Back Pain

Date

2021-08

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Abstract

Low-back pain (LBP) is a common musculoskeletal disorder and without intervention can detrimentally affect one’s quality of life. Interventions targeting trunk neuromuscular control are thought to serve as a meaningful clinical intervention that may reduce pain and improve function. The abdominal bracing maneuver (ABM) increases activity of the deep lumbar muscles that include internal oblique (IO) and multifidus (MF), as well as superficial muscles that include the external oblique (EO) and erector spinae (ES). This dissertation examined the effects of ABM on neuromuscular and biomechanical outcomes in chronic low back pain (cLBP) subjects. This investigation took place at the Clinical Musculoskeletal Laboratory at the Texas Tech University Health Sciences Center. Healthy and cLBP subjects consisted of a sample of convenience from the Texas Tech University System’s Institutions and the surrounding Lubbock community. This investigation incorporated a 3-factor repeated measures design that examined neuromuscular and biomechanical responses to an ABM in cLBP subjects versus asymptomatic controls. Each subject performed a loaded forward reach (LFR) movement across three separate conditions. Additionally, correlation analyses were performed to examine associations between CoP trajectories, kinesiophobia, disability, and current pain intensity in cLBP subjects. Lastly, a principal component analysis (PCA) was performed to identify multi-muscle synergies between cLBP and control subjects, with and without ABM, during an LFR. This is one of the first investigations to analyze the effects of pain, ABM on neuromuscular amplitudes, multi-muscle synergies, and biomechanical control outcomes during a LFR movement. In this study, 25 asymptomatic control (17 female, 8 male) and 24 cLBP (19 female, 5 male) subjects performed five naturally braced LFR trials for condition one (C1), followed by learning and sufficiently practicing the ABM. Subsequently, each subject performed an additional five trials of each: (a) condition two (C2) LFR with a relaxed trunk strategy and (b) condition three (C3) LFR with ABM. Normalized root-mean-square amplitude (RMS), via surface electromyography (EMG) was assessed for several trunk and lower extremity muscles. Additionally, center of pressure (CoP) trajectories in the anterior-posterior and medial-lateral directions were measured and recorded. Finally, Pearson R correlation statistics were employed to analyze the relationships between CoP variables and self-reported pain, disability, and fear of movement scores in cLBP subjects.

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Keywords

low back pain, motor control, volitional preemptive abdominal contraction, electromyography, kinetics, loaded forward reach

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