The purpose of this study was to investigate whether magnitude of trunk movement during rising from supine was related to displacement of HAT COG toward rolling side.
A way to rise from supine described Sarnacki’s roll off (rising from supine with trunk rotation and flexion,1985) was calculated in present research. 11 healthy males (averaged age 22.7±3.3) who unrestrictedly rise toward right from supine in optimal speed. The motions of rising from supine were recorded using four video cameras. Average of execution time in optimal speed was 2.85±0.61 seconds. Motion data was digitized in twenty-nine body landmarks using Frame-DIAS4 software (DKH, Japan). A model was comprised 16 rigid body segments: head, chest, upper trunk, lower trunk (pelvic girdle), arms, forearms, hands, thighs, legs, and feet. Kinematic data of trunk, shoulder joint both rolling side and un-rolling side were calculated.
Magnitude of trunk rotation angle during rising from supine influenced the displacement HAT COG toward rolling side. Correlation analysis was performed on HAT COG toward rolling side, between actual trunk rotation angle toward rolling side and bilateral shoulder joint angle. Pearson regression analysis was used.
Average peak HAT COG toward rolling side was 14.4±0.9cm. Average peak angle values of trunk rotation toward rolling side was 20.4±10.6 degree. Trunk rotation angle demonstrated a significant positive correlation with displacement of HAT COG (r=0.71, p0.01). In addition, flexion angle of shoulder joint on rolling side and flexion and abduction angle of shoulder joint on un-rolling side demonstrated a significant positive correlation with displacement of HAT COG (r=0.77, p0.01; r=0.87, p0.001; r=0.71, p0.005 respectively).
Trunk rotation toward rolling side was directly showed to elongate the HAT COG toward rolling side. Because the trunk has a large mass, the voluntary control and mobility of the trunk segment are very important to elongate of HAT COG on rising from supine. And it was clarified in present study that contralateral upper limb on rolling side did not interfere with the displacement of HAT COG toward rolling side.
This study will be useful for understanding basic movements in biomechanical physical therapy education.
Rising from supine
Three-dimensional analysis
