Validity of Maximal Exercise Testing in People With Multiple Sclerosis and Low to Moderate Levels Disability

Background. Cardiopulmonary exercise testing can be considered the gold standard for assessing cardiorespiratory fitness. Little is known about the criteria for maximal exercise testing in people with multiple sclerosis (MS) and how these criteria behave across different levels of neurological disability. Objective. The study objectives were to determine the criteria for maximal exercise testing across various levels of disability and to assess concomitant subgroup differences in measures related to the participant, disease, and function. Design. This was a cross-sectional study. Methods. Cardiopulmonary exercise testing was conducted with a sample of 56 participants with MS. Analysis of variance was used to assess the criteria in participants with MS and low, mild, and moderate levels of disability. Results. Mean peak oxygen consumption (Vo(2)peak) was 21.4 (SD=7.1) mL"kg-1 "miti-1. An oxygen consumption (Vo(2)) plateau was seen in 37.5% of participants. A respiratory exchange ratio of 1.10 or greater was achieved by 69.6% of the participants, a maximal heart rate within 90% of their age-predicted maximal heart rate was achieved by 48.2% of the participants, and 23.2% of the participants perceived their exertion to be 18 or greater on the Borg Scale of Perceived Exertion (scores of 6-20). The values for achieved heart rate and incidence of a Vo2 plateau were significantly lower in participants with moderate levels of disability than in those with mild levels of disability. Limitations. The primary limitations of this study were its cross-sectional nature and relatively small sample of participants with moderate levels of disability. Conclusion. The findings suggest that the outcome of cardiopulmonary exercise testing in people with MS and low to mild levels of disability (Expanded Disability Status Scale scores of 4.0) is a valid measure of cardiorespiratory fitness, whereas the outcome in people with moderate levels of disability (Expanded Disability Status Scale scores of >4.0) is most likely symptom limited.