Reliability of Submaximal Graded Exercise Testing of Male Subjects with SCI Using a Wheelchair Ergometer

Abstract

The purpose of this study was to determine the reliability of the wheelchair ergometer (WERG) in testing the metabolic cost of propulsion. A sample of convenience of 11 healthy male subjects with Spinal Cord Injury (SCI), one subject C5, ten subjects T6-L1, ages 18-47 (mean 34.5 ± 8.8), were tested three non-consecutive days, specifically with one week intervals. Subjects were taken through a submaximal exercise test to approximate 85% of their maximum predicted heart rate. Stages of the test were increased by 5 watts every 90 seconds. Throughout the test period, physiological measurements included: minute ventilation (V̇E), oxygen consumption in ml O2/Kg•min (V̇O2), heart rate (HR), respiratory exchange ratio (RER), and rating of perceived exertion (RPE). Anxiety level was measured by the Spielberger State Trait Anxiety Scale (SSTAS) prior to each exercise session. An evaluation of means using a one-way ANOVA for repeated measures revealed a significant difference in V̇O2 and RER among tests, while Intraclass Correlation Coefficient (ICC) revealed high correlation (ICC = .92, .86), respectively. These differences occurred among tests 1 and 2. No significant differences were found in the mean HR, duration, or V̇E between test sessions. An evaluation of the peak values using a one-way ANOVA for repeated measures revealed no significant differences in HR, V̇O2, RER, or V̇E among tests, while the ICC revealed high to very high correlation (ICC = .91, .92, .84, .74). The RPE and the SSTAS rank scores were evaluated using Friedman's test for nonparametric data and showed no significant results. These findings indicate that the WERG can be used as a reliable instrument for evaluating physiological and psychological variables during wheelchair propulsion in this SCI population.