Objective:To observe the characteristics of multi-muscle surface electromyography (sEMG) network indices during static standing among hemiplegic stroke survivors, and to evaluate the value of the indices in assessing neuromuscular dysfunction.Methods:Ten male stroke survivors with hemiplegia were recruited into the hemiplegia group, and 10 age-matched healthy males were chosen as the control group. Both groups were required to perform 30s static standing tasks with their eyes open and closed. The sEMG signals from the bilateral gluteus maximus (GM), rectus femoris (RF) and biceps femoris (BF) muscles were synchronously collected. Linear time-frequency domain indices were then calculated from the sEMG signals, including the root mean square (RMS) and median frequency (MF). Network indices were extracted from the multiplex recurrence network and weighted networks were constructed from the sEMG signals, including the average interlayer mutual information (I), average edge overlap (ω), clustering coefficient (C), average shortest path length (L) and degree of centrality (DC).Results:With the eyes closed, the RMS values of the bilateral GMs of the hemiplegia group, as well as the values for the RF and BF on the unaffected side were significantly higher than the control group′s values. In the hemiplegia group, the RMS values of the RF and BF muscles on the unaffected side were significantly higher than on the affected side during standing with the eyes closed. For the RF muscles the RMS values on the unaffected side were, on average, significantly higher than with the eyes open. The MF of the GM muscles on the unaffected side in the hemiplegia group was significantly lower than the average MF values of the bilateral GM muscles in the control group with the eyes open or closed. With the eyes closed, the MF of the unaffected-side GM was significantly lower than that of the affected-side GM in the hemiplegia group. Compared with the control group, the hemiplegia group showed a significant increase in I and ω values, but a significant decrease in L values with the eyes open or closed. The DC values of the bilateral GM, RF and BF muscles in the hemiplegia group were significantly higher than among the control group with the eyes open, which was also true of the bilateral GM and RF muscles with the eyes closed. With the BF muscles it was true only of the unaffected side. In the hemiplegia group, the DC values of the unaffected-side GM with the eyes open or closed, and of the unaffected-side BF with the eyes closed.Conclusions:When standing still, hemiplegic stroke survivors exhibit increased overall synchronous muscle adjustment with involvement of unaffected-side muscles, especially the GM. sEMG network indices such as I, ω, L and DC can assess multi-muscle synchronous adaptability and the involvement of single muscles. sEMG network algorithms thus have potential as a new method for localizing and quantitatively assessing neuromuscular dysfunction among such patients.

Objective:To observe the characteristics of multi-muscle surface electromyography (sEMG) network indices during static standing among hemiplegic stroke survivors, and to evaluate the value of the indices in assessing neuromuscular dysfunction.Methods:Ten male stroke survivors with hemiplegia were recruited into the hemiplegia group, and 10 age-matched healthy males were chosen as the control group. Both groups were required to perform 30s static standing tasks with their eyes open and closed. The sEMG signals from the bilateral gluteus maximus (GM), rectus femoris (RF) and biceps femoris (BF) muscles were synchronously collected. Linear time-frequency domain indices were then calculated from the sEMG signals, including the root mean square (RMS) and median frequency (MF). Network indices were extracted from the multiplex recurrence network and weighted networks were constructed from the sEMG signals, including the average interlayer mutual information (I), average edge overlap (ω), clustering coefficient (C), average shortest path length (L) and degree of centrality (DC).Results:With the eyes closed, the RMS values of the bilateral GMs of the hemiplegia group, as well as the values for the RF and BF on the unaffected side were significantly higher than the control group′s values. In the hemiplegia group, the RMS values of the RF and BF muscles on the unaffected side were significantly higher than on the affected side during standing with the eyes closed. For the RF muscles the RMS values on the unaffected side were, on average, significantly higher than with the eyes open. The MF of the GM muscles on the unaffected side in the hemiplegia group was significantly lower than the average MF values of the bilateral GM muscles in the control group with the eyes open or closed. With the eyes closed, the MF of the unaffected-side GM was significantly lower than that of the affected-side GM in the hemiplegia group. Compared with the control group, the hemiplegia group showed a significant increase in I and ω values, but a significant decrease in L values with the eyes open or closed. The DC values of the bilateral GM, RF and BF muscles in the hemiplegia group were significantly higher than among the control group with the eyes open, which was also true of the bilateral GM and RF muscles with the eyes closed. With the BF muscles it was true only of the unaffected side. In the hemiplegia group, the DC values of the unaffected-side GM with the eyes open or closed, and of the unaffected-side BF with the eyes closed.Conclusions:When standing still, hemiplegic stroke survivors exhibit increased overall synchronous muscle adjustment with involvement of unaffected-side muscles, especially the GM. sEMG network indices such as I, ω, L and DC can assess multi-muscle synchronous adaptability and the involvement of single muscles. sEMG network algorithms thus have potential as a new method for localizing and quantitatively assessing neuromuscular dysfunction among such patients.