The influence of musculoskeletal pain disorders on muscle synergies—A systematic review

Abstract

BackgroundMusculoskeletal (MSK) pain disorders represent a group of highly prevalent and often disabling conditions. Investigating the structure of motor variability in response to pain may reveal novel motor impairment mechanisms that may lead to enhanced management of motor dysfunction associated with MSK pain disorders. This review aims to systematically synthesize the evidence on the influence of MSK pain disorders on muscle synergies.MethodsNine electronic databases were searched using Medical Subject Headings and keywords describing pain, electromyography and synergies. Relevant characteristics of included studies were extracted and assessed for generalizability and risk of bias. Due to the significant heterogeneity, a qualitative synthesis of the results was performed.ResultsThe search resulted in a total of 1312 hits, of which seven articles were deemed eligible. There was unclear consistency that pain reduced the number of muscle synergies. There were low consistencies of evidence that the synergy vector (W weights) and activation coefficient (C weights) differed in painful compared to asymptomatic conditions. There was a high consistency that muscle synergies were dissimilar between painful and asymptomatic conditions.ConclusionsMSK pain alters the structure of variability in muscle control, although its specific nature remains unclear. Greater consistency in muscle synergy analysis may be achieved with appropriate selection of muscles assessed and ensuring consistent achievement of motor task outcomes. Synergy analysis is a promising method to reveal novel understandings of altered motor control, which may facilitate the assessment and treatment of MSK pain disorders.

Myofascial trigger points alter the modular control during the execution of a reaching task: a pilot study

“…Despite the evidence of an alteration of weighting coefficients is inconsistent when muscle pain is induced experimentally 33 , the present results highlight for the first time that TPs influence how much a muscle is involved in a module. The model run on the influence of TP presence (ACT, LAT, NO) on the weighting coefficients, used to understand the amount of muscle involvement within a module confirmed our Hypothesis 2 that a TP altered the weighting coefficients of the muscle with the TP when it is involved in the motor modules as dominant.…”

“…The number of extracted modules varied among subjects, suggesting that TP presence may alter the dimensionality of the individual modules structure. A recent review reported an inconsistent evidence of the influence of musculoskeletal pain on the number of modules extracted according to VAF values, with studies reporting a decreased, an increased or a similar number of modules 33 . The regression analysis reported herein showed no correlations between individual number of extracted modules and number of TP or presence of active TP.…”

“…A motor module is a group of muscles controlled as a single unit 24 that is spatially and temporally characterized through the directional tuning of its weighting and timing coefficients, respectively 25 . This approach has already been used to describe complex human motor behaviors like walking, in infants 26 , healthy adults 27 and neurological patients 28 ; reaching task, in healthy 29–31 and stroke subjects 32 ; and in presence of various musculoskeletal pain syndromes 33 . Despite an influence of TP on motor modules has been hypothesized 17 , an investigation of the influence of TP at the level of modular motor control has not been performed so far.…”

Investigating the Causal Mechanisms of Symptom Recovery in Chronic Whiplash-associated Disorders Using Bayesian Networks

“…Alternatively, findings from the present study suggests that global (multimuscle), rather than local (single muscle), physiological measures are more important mediators of pain recovery in exercise-based interventions. Muscles typically work in functional groups and the individual functioning of a muscle can be compensated by synergistic muscles [67].…”

Exploring the clinical presentation of tibialis posterior tendinopathy

“…Previous research has identified that the biomechanical characteristics and TP muscle activity required during the push-off phase of gait are similar to those during a SLHR. 218 Alterations in muscle activity and coordination occur in the presence of musculoskeletal pain [219][220][221] and may be related to changes in movement patterns which occur when there is pain and dysfunction. Electromyographic (EMG) studies investigating muscle activity during walking in TPT are limited.…”