Predicting Exercise Capacity Through Submaximal Fitness Tests in Persons With Multiple Sclerosis

OBJECTIVE: To estimate, for persons with multiple sclerosis (MS), the extent to which peak oxygen consumption (Vo(2)peak) can be predicted by the results on submaximal tests. DESIGN: Cross-sectional study. SETTING: Three MS clinics in the Greater Montreal region, Canada. PARTICIPANTS: A center-stratified random sample of 135 women and 48 men was drawn (N=183). A subgroup of 59 subjects with MS, who were able to perform the step test, was selected from this sample to complete the maximal exercise test. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Vo(2)peak. RESULTS: In this sample (mean age +/- SD, 39 +/- 9 y; median Expanded Disability Status Scale=1.5), the mean Vo(2)peak +/- SD was 27.6 +/- 7.3 mL.kg(-1).min(-1). This value is considerably low when compared with healthy persons, ranking below the 25th percentile for both men and women. In a multivariate regression analysis, the step test and grip strength were identified as the only significant predictors of Vo(2)peak. When combined with body weight, grip strength and the step test explained 74% of the variance in Vo(2)peak. CONCLUSIONS: Patients with MS with a mild degree of disability exhibit marked reductions in exercise capacity. Also, in persons with MS, submaximal tests are good predictors of exercise capacity. These measures may be used in clinical settings to help assess and monitor maximum oxygen consumption and in research to evaluate the effect of exercise-related interventions. Furthermore, they will allow people with MS to self-monitor their exercise capacity and be more actively engaged in taking charge of their fitness level.