Biosignal processing methods to explore the effects of side-dominance on patterns of bi- and unilateral standing stability in healthy young adults

Changes in scapular and trunk angles and postural control during right-left hand-behind-back movement

[Purpose] This study aimed to clarify the changes in the scapulothoracic joint and upper trunk angles and postural control during right-left hand-behind-back (HBB) movement. [Participants and Methods] The participants were 20 healthy right-handed men. We measured the HBB movement while standing using a three-dimensional motion capture system. Changes in the internal rotation angle of the scapulothoracic joint, upper trunk rotation angle, and center of pressure (COP) were examined to assess potential right-left differences between the analyzed positions. [Results] As the thumb touched the buttocks, upper trunk contralateral and scapulothoracic joint internal rotations were observed and the COP on the non-HBB side was significantly displaced laterally. There were no right-left differences in the changes between the analyzed positions for all measures. [Conclusion] Upper trunk contralateral rotation and postural control were conducted without right-left differences during HBB movement. These results suggest that upper trunk movement and standing postural control are involved in HBB movement. Therefore, it is useful to focus on the scapulothoracic joint angle, upper trunk rotation angle, and standing postural control during physical therapy evaluation and treatment with HBB movement.

Clinical significance of dynamical network indices of surface electromyography for reticular neuromuscular control assessment

BACKGROUND

There is currently no objective and accurate clinical assessment of reticular neuromuscular control in healthy subjects or patients with upper motor neuron injury. As a result, clinical dysfunctions of neuromuscular control could just be semi-quantified, efficacies and mechanisms of various therapies for neuromuscular control improving are difficult to verify.

METHODS

Fourteen healthy participants were required to maintain standing balance in the kinetostatics model of Gusu Constraint Standing Training (GCST). A backward and upward constraint force was applied to their trunk at 0°, 20° and 25°, respectively. The multiplex recurrence network (MRN) was applied to analyze the surface electromyography signals of 16 muscles of bilateral lower limbs during the tests. Different levels of MRN network indices were utilized to assess reticular neuromuscular control.

RESULTS

Compared with the 0° test, the MRN indices related to muscle coordination of bilateral lower limbs, of unilateral lower limb and of inter limbs showed significant increase when participants stood in 20° and 25° tests (P < 0.05). The indices related to muscle contribution of gluteal, anterior thigh and calf muscles significantly increased when participants stood in 20° and 25° tests (P < 0.05).

CONCLUSIONS

This study applied the dynamical network indices of MRN to analyze the changes of neuromuscular control of lower limbs of healthy participants in the kinetostatics model of GCST. Results showed that the overall coordination of lower limb muscles would be significantly enhanced during performing GCST, partly by the enhancement of neuromuscular control of single lower limb, and partly by the enhancement of joint control across lower limbs. In particular, the muscles in buttocks, anterior thighs and calves played a more important role in the overall coordination, and their involvement was significantly increased. The MRN could provide details of control at the bilateral lower limbs, unilateral lower limb, inter limbs, and single muscle levels, and has the potential to be a new tool for assessing the reticular neuromuscular control. Trial registration ChiCTR2100055090.