The effect of the partially restricted sit-to-stand task on biomechanical variables in subjects with and without Parkinson’s disease Luciane Aparecida Pascucci Sande de Souza a , Mônica de Biagi Curtarelli b , Mukul Mukherjee c , Valdeci Carlos Dionisio d,⇑ a Physical Therapy Course, Federal University of Triângulo Mineiro, Brazil b Physical Therapy Course, University of Ribeirão Preto, Brazil c University of Nebraska at Omaha, Department of Health, Physical Education and Recreation, Omaha, NE, USA d Physical Therapy Course, Federal University of Uberlândia, Brazil article info Article history: Received 14 February 2011 Received in revised form 21 April 2011 Accepted 29 April 2011 Available online xxxx Keywords: Electromyography Kinetics Kinematics Sit-to-stand Parkinson’s disease abstract The aim of this study was to explore the electromyographic, kinetic and kinematic patterns during a par- tially restricted sit-to-stand task in subjects with and without Parkinson’s disease (PD). If the trunk is par- tially restricted, different behavior of torques and muscle activities could be found and it can serve as a reference of the deterioration in the motor performance of subjects with PD. Fifteen subjects participated in this study and electromyography (EMG) activity of the tibialis anterior (TA), soleus (SO), vastus medi- alis oblique (VMO), biceps femoris (BF) and erector spinae (ES) were recorded and biomechanical vari- ables were calculated during four phases of the movement. Subjects with PD showed more flexion at the ankle, knee and hip joints and increased knee and hip joint torques in comparison to healthy subjects in the final position. However, these joint torques can be explained by the differences in kinematic data. Also, the hip, knee and ankle joint torques were not different in the acceleration phase of movement. The use of a partially restricted sit-to-stand task in PD subjects with moderate involvement leads to the gen- eration of joint torques similar to healthy subjects. This may have important implications for rehabilita- tion training in PD subjects. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Rising from a seated position is a basic functional task, incorpo- rated in daily life functions (Krajl et al., 1990; Reisman et al., 2002). Like other motor tasks, sit-to-stand has been investigated with the purpose of providing quantitative information regarding the indi- vidual’s functional status. Sit-to-stand has been identified as one of the most mechanically demanding motor tasks among activities of daily life, confirming the general acceptance of their effective- ness as indicators of the mobility level (Goulart and Valls-Solé, 1999; Hughes et al., 1996; Kerr et al., 1997; Mazzà et al., 2005). Standing up from sitting is a complex task characterized by the transfer from one stabilized posture to another with movements of all body segments except the feet. The transfer from sitting to standing requires voluntary movements of different body seg- ments that contribute to the change of posture and equilibrium control during the displacement of the body center of mass (COM) (Mourey et al., 1998; Van der Burg et al., 2006). Given that safe and efficient performance of standing up is often problematic in individuals with disabilities, an understanding of the biome- chanical parameters in health and in presence of disease is very important (Reisman et al., 2002). During sit-to-stand, characteristic biomechanical changes occur in a sequential manner. The forward momentum is generated for sit-to-stand initiation and is followed by seat unloading and verti- cal acceleration (Inkster and Eng, 2004). Vertical acceleration re- quires large leg-extensor strength and joint ranges of motion (Krajl et al., 1990; Hughes et al., 1996) specifically of the hip (Pää- suke et al., 2004). Chair heights also have a significant role to play in the generation of knee extension moment with the maximum isometric knee strength being required to rise from the lowest chair (Hughes et al., 1996). During sit-to-stand, Parkinson’s disease (PD) subjects demon- strate a large proportion of co-contraction because they move slower (Bishop et al., 2005). Moreover, PD subjects generate large preparatory hip flexion displacement and forward COM displace- ment for reduced knee extensor moments (Inkster and Eng, 2004). During sit-to-stand, subjects with PD generate 40% smaller peak hip flexion torque than healthy subjects because they 1050-6411/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jelekin.2011.04.007 ⇑ Corresponding author. Address: Federal University of Uberlândia, Physical Therapy, Rua Benjain Constant, 1286, Aparecida, 38.400-678 Uberlândia, Minas Gerais, Brazil. Tel.: +55 34 32182945; fax: +55 34 32182910. E-mail address: vcdionisio@gmail.com (V.C. Dionisio). Journal of Electromyography and Kinesiology xxx (2011) xxx–xxx Contents lists available at ScienceDirect Journal of Electromyography and Kinesiology journal homepage: www.elsevier.com/locate/jelekin Please cite this article in press as: Sande de Souza, LAP et al. The effect of the partially restricted sit-to-stand task on biomechanical variables in subjects with and without Parkinson’s disease. J Electromyogr Kinesiol (2011), doi:10.1016/j.jelekin.2011.04.007