Characterizing stroke-induced changes in the variability of lower limb kinematics using multifractal detrended fluctuation analysis

Abstract

Movement variability reflects the adaptation of the neuromuscular control system to internal or external perturbations, but its relationship to stroke-induced injury is still unclear. In this study, the multifractal detrended fluctuation analysis was used to explore the stroke-induced changes in movement variability by analyzing the joint angles in a treadmill-walking task. Eight healthy subjects and ten patients after stroke participated in the experiment, performing a treadmill-walking task at a comfortable speed. The kinematics data of the lower limbs were collected by the motion-capture system, and two indicators, the degree of multifractality (α) and degree of correlation [h(2)], were used to investigate the mechanisms underlying neuromuscular control. The results showed that the knee and ankle joint angles were multifractal and persistent at various scales, and there was a significant difference in the degree of multifractality and the degree of correlation at the knee and ankle joint angles among the three groups, with the values being ranked in the following order: healthy subjects < non-paretic limb < paretic limb. These observations highlighted increased movement variability and multifractal strength in patients after stroke due to neuromotor defects. This study provided evidence that multifractal detrended analysis of the angles of the knee and ankle joints is useful to investigate the changes in movement variability and multifractal after stroke. Further research is needed to verify and promote the clinical applications.

Exploring Acute Changes in Hamstring EMG after Warm-up and Stretching Using a Multifractal Analysis

“…The polynomial m-order fitting and scaling regions are two main parameters. As previously computed, different m-order polynomial functions were fitted, and we chose the second-order polynomial fit (m = 2) (28,37). Increasing the polynomial produced a slight downward and rightward shift of the fluctuation function (Fig.…”

“…3A). As previously observed, F decreased with increasing the m-order because of a smaller residual (37). As previously used for surface EMG recordings (28), we chose the second-order (i.e., m = 2) detrended polynomial to perform MFDFA.…”

Biomechanical Assessment Methods Used in Chronic Stroke: A Scoping Review of Non-Linear Approaches

“…Of the 14 included studies, 6 only included post-stroke subjects [19,28,30,[33][34][35], and 8 also included healthy subjects [18,27,29,31,32,[36][37][38]. The sample size of chronic poststroke participants ranged from 3 [37] to 23 [29].…”

“…A total of 150 chronic post-stroke subjects, 102 men and 51 women, with a mean age of 52.33 years, were included in the studies. All the subjects were at a chronic stage, ranging from 12.67 [37] to 177.34 [18] months after stroke, and presented with a single and unilateral [18,19,27,28,30,33,35,37,38] or multiple and unilateral strokes [29]. Two studies did not report lesion characteristics [32,39].…”

“…According to the type of stroke, four trials included both ischemic and hemorrhagic stroke [19,30,32,37] and three trials analyzed only ischemic stroke [27,28,33]. Overall, seven trials did not report the type of stroke [18,29,31,[34][35][36]38]. Only one study reported the location of the stroke [19,33].…”