Descending Systems Translate Transient Cortical Commands into a Sustained Muscle Activation Signal

The role of the hand is crucial for the performance of activities of daily living, thereby ensuring a full and autonomous life. Its motion is controlled by a complex musculoskeletal system of approximately 38 muscles. Therefore, measuring and interpreting the muscle activation signals that drive hand motion is of great importance in many scientific domains, such as neuroscience, rehabilitation, physiotherapy, robotics, prosthetics, and biomechanics. Electromyography (EMG) can be used to carry out the neuromuscular characterization, but it is cumbersome because of the complexity of the musculoskeletal system of the forearm and hand. This paper reviews the main studies in which EMG has been applied to characterize the muscle activity of the forearm and hand during activities of daily living, with special attention to muscle synergies, which are thought to be used by the nervous system to simplify the control of the numerous muscles by actuating them in task-relevant subgroups. The state of the art of the current results are presented, which may help to guide and foster progress in many scientific domains. Furthermore, the most important challenges and open issues are identified in order to achieve a better understanding of human hand behavior, improve rehabilitation protocols, more intuitive control of prostheses, and more realistic biomechanical models.

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A comparison of functional movement patterns between female low back pain developers and non-pain developers

Work ◽

10.3233/wor-213545 ◽

2021 ◽

pp. 1-8

Author(s):

Fatemeh Khoshroo ◽

Foad Seidi ◽

Reza Rajabi ◽

Abbey Thomas

Keyword(s):

Low Back Pain ◽

Back Pain ◽

Muscle Activation ◽

Statistical Significance ◽

Movement Patterns ◽

Composite Score ◽

Quality Data ◽

Low Back ◽

Functional Movement ◽

Prolonged Standing

BACKGROUND: Distinctive features of low back pain-developers (LBPDs) as pre-clinical low back pain (LBP) population have been evidenced in three areas of alignment, muscle activation, and movement patterns. To clarify whether the reported altered functional movement patterns in chronic LBP patients result from or result in LBP disorders, LBPDs’ functional movement patterns should be investigated. OBJECTIVES: This study aimed to compare female LBPDs’ functional movement patterns with non-pain developers’ (NPDs). METHODS: Sixty female LBPDs and NPDs were recruited based on the research requirements. The Functional Movement Screen (FMS) was used to investigate movement quality. Data were compared between groups via Mann-Whitney U tests and correlation analyses examined association between pain intensity and onset during prolonged standing and the FMS score. Receiver Operating Characteristic Curves and Chi Squares were conducted to find the best cutoff points. An alpha level of p≤0.05 was used to establish statistical significance. RESULTS: LBPDs scored significantly lower, or rather worse than NPDs in the FMS composite score (12.06±1.33 vs. 16.43±1.59, U = 3, P < 0.001). Moreover, the optimal cutoff scores of≤14 on the FMS, 2 on the push-up, and 1 on the deep squat discriminated between female LBPDs and NPDs. The FMS composite score was correlated negatively with LBP intensity (r (60) = –0.724, p < 0.001) and positively with LBP onset (r (60) = 0.277, p = 0.032) during prolonged standing. Finally, the results indicated that female LBPDs presented with at least one bilateral asymmetry on the FMS had 10 times (95%CI, 2.941–34.008) and with at least two bilateral asymmetries on the FMS had 15.5 times (95%CI, 3.814–63.359) higher odds of developing LBP during prolonged standing than NPDs. CONCLUSIONS: Female LBPDs, who are at higher risk for developing LBP in the future, have significantly lower quality of functional movement patterns compared to NPDs. Moreover, the FMS appears to show promise for predicting individuals who are at risk for LBP development during prolonged standing.

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