Kinematic and electromyographic analyses of normal and device-assisted sit-to-stand transfers

Mechanical sit-to-stand devices assist patient transfers and help protect against work-related injuries in rehabilitation environments. However, observational differences between patient's movements within devices compared to normal sit-to-stand transfers deter clinician use. This study compared kinematics and muscle demands during sit-to-stand transfers with no device (ND), and device-assisted during which participants exerted no effort (DA-NE) and best effort (DA-BE). Coefficient of multiple correlations (CMCs) compared kinematic profiles during each device-assisted condition to ND. Compared to DA-NE, CMCs were higher during DA-BE at the hip, knee, and ankle. However, DA-BE values were lower than DA-NE at the trunk and pelvis due to the device's mechanical constraints. In general, all joints' final DA-NE postures were more flexed than other conditions. Electromyographic was significantly lower during DA-NE compared to ND for all muscles except lateral hamstring, and during DA-BE compared to ND for gluteus maximus, gastrocnemius, and soleus. Verbal encouragement (DA-BE) significantly increased medial hamstring, vastus lateralis, gastrocnemius, soleus and tibialis anterior activation compared to DA-NE. In conclusion, device-assisted sit-to-stand movements differed from normal sit-to-stand patterns. Verbally encouraging best effort during device-assisted transfers elevated select lower extremity muscle activation and led to greater similarity in hip, knee and ankle movement profiles. However, trunk and pelvis profiles declined. (C) 2012 Elsevier B.V. All rights reserved.