D-23 Free Communication/Poster - Cardiovascular Disease and Rehabilitation MAY 29, 2008 1:00 PM - 6:00 PM ROOM: Hall B
Sense of motor effort (SOE) governs our ability to produce appropriate levels of muscular force or effort required to execute specific motor tasks. Previous studies suggested that SOE maybe impaired by stroke. There are currently no standardized quantitative methods of assessing SOE in stroke.
PURPOSE: To examine the viability of a quantitative method for assessing the effects of stroke on SOE using five effort levels (EL) on a Sense of Effort Rating Scale (SOERS).
METHODS: Four moderately impaired chronic stroke survivors (CSS) aged 55-65 mean 62.5 ± 3.70 SD) were seated in an upright position on a Biodex® isokinetic dynamometer such that elbow joint flexion and extension movements occurred in the horizontal plane. In this position, the CSS first performed maximum voluntary contraction (MVC) of their less-affected elbow flexors and extensors at 90 degrees joint angle. The CSS were thereafter instructed to perform isometric elbow flexion and extension tasks at five randomly pre-assigned sub-maximal EL of 1, 3, 5, 7 and 9 on the SOERS. These sub-maximal EL were subjectively perceived by the CSS to be equivalent to 10%, 30%, 50%, 70% and 90% of their MVC. The procedure was then repeated for the more-affected extremity. The joint torques were normalized to MVC, processed and analyzed using a Wilcoxon signed-rank test to assess the sensitivity of the SOERS to detect SOE changes across the five EL. A Cronbach's alpha test was also used to assess the internal consistency of the SOERS.
RESULTS: Our results showed that using their more-affected extremity, CSS were able to quantify and discriminate between EL 1-3, 3-5 and 5-7 (p=0.06, 0.018 and 0.025 respectively), but could not discriminate between EL 7-9 (p=0.306) on the SOERS. A Cronbach's Alpha of 0.828 revealed high internal consistency of the SOERS in assessing SOE in stroke. They were able to discriminate between all EL with their less-affected extremity.
CONCLUSIONS: This preliminary study suggests that SOE is impaired by stroke and can be assessed quantitatively using the SOERS. Further, moderately impaired CSS were unable to discriminate changes in muscular effort beyond 70% of their MVC. The SOERS as used in this study may therefore be used as a tool for monitoring rehabilitation progress and recovery of motor functions in stroke survivors if submaximal motor effort is required.