Functional walk tests in individuals with stroke - Relation to perceived exertion and myocardial exertion

Background and Purpose - Functional walk tests such as the 6- and 12-Minute Walk Test (i.e, 6MWT and 12MWT, respectively) are submaximal measures used to determine functional capacity in individuals with compromised ability. The purpose of this study was to determine the relationship between these walk tests and measures of exertion (perceived and myocardial), in addition to impairment in individuals with stroke. The relationship among the 6MWT, 12MWT, and the more traditionally assessed measure of self-paced gait speed (generally assessed over a short distance, eg, 10 m) was also evaluated. Methods - Twenty-five community-dwelling individuals with stroke were evaluated for the following: 12MWT distance, 6MWT distance, self-paced gait speed over 8 m, plantarflexion strength, Berg Balance Scale, Ashworth Scale of Spasticity, and Chedoke-McMaster Stroke Assessment. Heart rate (HR), rate-pressure product (RPP), and perceived exertion were assessed during the functional walk tests. Correlational analysis quantified the relationship between gait, impairment measures, and physiological responses during the functional walk tests. Results - HR reached a steady state after 6 minutes and reflected a moderate exercise intensity of 63% of age-predicted maximum HR. The 6MWT, 12MWT, and self-paced gait speed were all highly correlated with one another (r > 0.90) and were all also related to the severity of impairments. The functional walk distances did not relate either to perceived exertion or actual exertion (increase in the myocardial oxygen demand as measured by RPP). Conclusions - Stroke- specific impairments are the major limitations to the distance walked in individuals with stroke. If the functional walk test is used to assess performance of an individual over time (eg, in response to an intervention), we recommend that both exertion (eg, increase in RPP or HR) and distance be measured.