Activation of selected frontal trunk and extremities muscles during rolling from supine to side lying in healthy subjects and in post-stroke hemiparetic patients

The purpose of this work was to get insight into the role of frontal trunk and proximal extremity muscles in rolling from supine to side lying. Participants were seventeen hemiparetic patients and 14 healthy subjects. Electromyographic (EMG) activity of the Sternocleidomasoid (ScM), Pectoralis Major (PM), External Oblique (ExO) and Rectus Femoris (RF) muscle pairs was recorded during rolling performance. Analysis included the establishment of EMG response times and magnitudes. For all muscles, initiation of EMG activity was delayed in the patients as compared with the controls. Among the healthy subjects, EMG activity level of the SCM was more enhanced on the mobile than on the stable body side, while activation level of the PM muscle was larger on the stable body side. In the hemiparetic group, the SCM demonstrated similar results as the controls yet, PM activity on the paretic side was lower than on the non-paretic side regardless of rolling direction. The difference in activation level between the corresponding ExO and RF muscles showed inconsistency among the healthy subjects, whereas in the hemipareic group the muscles on the paretic side never displayed higher activation levels than on the non-paretic side. In conclusion, rolling sideways in hemiparetic subjects is characterized by a normal relationship between activation levels of the SCM muscles while the relationship between the corresponding PM, ExO and RF muscles is hampered due to reduced activation level of the muscles on the paretic body side.