Effects of deficit of strength in the sit-to-stand task in people with multiple sclerosis

Abstract

To assess how the deficit of static strength associated with neurological and functional alterations caused by multiple sclerosis (MS) affects sit-to-stand (STS) performance. A comparative analysis of STS performance was conducted in four groups. 20 persons with MS, with an EDSS score <6.5, were divided into two groups based on sex and static strength of leg extensor muscles. Twenty healthy controls were allocated to another two groups based on the same criteria. STS performance was assessed by measuring ground reaction forces and 2D photogammetry. Participants with MS exhibited similar static strength that control groups, only in those persons with higher Expanded Disability Status Scale the deficit was higher. However, MS groups show lower dynamic strength during muscle extension in the STS task. This effect could be related to other alterations associated with MS such as postural control and coordination impairment. The MS sample with deficit of static strength took longer to perform the STS task (p<0.001), being the deceleration period the one that most contributed to delay (p<0.001). Although the static force is similar between groups with MS vs Controls groups, performance of the STS task is altered by dynamic strenght weakness and postural control and coordination factors that are related with the level of disability reported by MS through the EDSS scale.