Biomechanics of sit to stand Essays

Biomechanics of sit to stand Essays Biomechanics of sit to stand Paper Biomechanics of sit to stand Paper The capability of moving from a sitting to a standing position is considered as an essential marker for functional independence (Gill et al., 1995) as well as a determinant for risk of falls (Campbell et al., 1989). Specific balance examinations have been designed to determine the agility of an individual in standing up from a sitting position.   The score system employed in these balance tests is based on the time it takes to achieve the sit-to-stand action and an individual receiving a low score translates to a difficulty in standing up from a sitting position. The action of standing up from a seated position is an intricate action that is associated with the shift from one stable position to another through the engagement of technically all the parts of the body except the feet.   Hence the simultaneous action of sitting and standing involves two major aspects in musculoskeletal control.   Firstly, voluntary movement of several parts of the body facilitate in the transformation of a posture from sitting to standing. Secondly, control of equilibrium is also involved in change in posture because there is a change in the body’s centre of gravity (Cacciatore et al., 2005).   Such displacement is associated with the center of gravity moving forward and backward alongside vertical motion.   Biomedical science has considered the entire mechanism of the coupled sitting and standing postures as a valuable standard in studying the principles behind the synchronization of posture and movement. Several reports have suggested the posture and movement are associated with elderly individuals hence investigators have studied anticipatory postural reactions during actions of the arms which are generally more slowly performed. The biomechanics of these postural reactions have also been investigated using a platform that was in constant motion and these studies shows variations in magnitude and timing of movement of body segments between healthy older individuals and young control subjects.   Research regarding the action of standing up among young subjects revealed the different stages of movement using kinetic and kinematic data.   Other research efforts described the influence of the trunk to the change in the center of gravity. It has been reported that the employment of a high seat and the facilitative use of hands for pushing results in a lowering of the torque in the hips and knee joints. The standing position involves balance control as well as variations in the speed in performing the act and termination restrictions with changes in the standing position.   It was observed that the center of gravity was controlled in a horizontal direction and this represents an essential factor in maintaining the dynamic balance while performing the movement.   Investigations regarding the succession of stages from the standing to the sitting position using force platform data revealed that the time involved in sitting down is longer than the time involved in standing up. Majority of research efforts on the biomechanics of sitting down and standing up aimed to analyze and evaluate the kinetics of the entire action in order to provide a better understanding of the phases of movement in relation to gravity.   It has been observed that each phase of the movement is distinct from each other.   Research studies were also designed to determine the effect of age of an individual on the movement kinetics. Such research efforts on age-related kinetics reported that critical role of foot position and the centre of velocity in regulating the stability once an individual gets off the seated position.   It has been suggested that the main kinetic mechanism involved in sitting and standing actions that differentiates young individuals from the elderly is the first step of standing up or the rising up from the seated position.   There are differences in the kinetics of standing up among elderly individuals.   The two stages of movement composed of standing up and sitting down have been well studied. Angular displacement of the trunk is an essential component of the actions of standing up and sitting down.   Also known as the to-and-fro action, the first position and mechanical settings of this action is influenced by the effect of gravity.   The trajectories of the acromion in the sagittal plane have provided the proof the similar forms are observed in both the seated and standing positions. The tranjectories of both positions actually do not change during the movement.   However, the trajectory of the trochanter varies with regards to the function of the movements, which in turn are influenced by gravity and the posture of the individual during each stage.   It has been observed that the angular displacement of the trunk during the seated and the standing positions remain the same, when analyzed with respect to the vertical axis.