Comprehensive Profile of Cardiopulmonary Exercise Testing in Ambulatory Persons with Multiple Sclerosis

Background:  The study and application of exercise in multiple sclerosis (MS) often requires cardiopulmonary exercise testing (CPET) to provide a comprehensive assessment of exercise tolerance and responses, including an evaluation of the pulmonary, cardiovascular, and skeletal muscle systems. Research on CPET in persons with MS has considerable limitations including small sample sizes, often without controls; not reporting outcomes across disability status; and applying different modalities of exercise testing across studies. Although some key outcome variables of CPET have been studied in persons with MS, additional calculated variables have not been directly studied. 

Objectives: The objective of this study was to provide a comprehensive examination of outcome variables from CPET among persons with MS and healthy controls.

Methods: We enrolled 162 persons with MS and 80 healthy controls who underwent a CPET on a leg ergometer for measuring oxygen uptake (VO₂), carbon dioxide production (VCO₂), ventilation (VE), respiratory exchange ratio, work rate, and heart rate (HR). Calculated variables (i.e., ventilatory anaerobic threshold (VO₂/VCO₂), VE/VCO₂ slope, VO₂/Power slope, VO₂/HR slope, and Oxygen Uptake Efficiency Slope) were processed using standard guidelines. We examined differences in the CPET variables between groups (e.g., MS vs. controls & categories of mild, moderate, and severe disability status) using ANCOVA, controlling for age, sex, body mass index, and disease duration. 

Results: Overall, persons with MS demonstrate alterations in outcomes from CPET compared to controls and these are generally exacerbated with increasing disability.

Conclusions: Our results provide novel information for the evaluation of CPET in MS for developing exercise prescriptions and documenting adaptations with exercise training based on the comprehensive variables obtained during a CPET.