Heterogeneity of aerobic fitness changes with exercise training in progressive multiple sclerosis: Secondary, exploratory analysis of data from the CogEx trial

Background There is heterogeneity of aerobic fitness (VO2peak) changes with a standardized exercise training stimulus in the general population (i.e. some participants demonstrate improvements, others no change, and some a reduction in VO2peak). Objectives This secondary, exploratory analysis of data examined the heterogeneity of VO2peak responses and possible correlates among persons with progressive multiple sclerosis (PMS) from the CogEx trial. Methods CogEx was a multi-site, multi-arm, randomized, double-blinded, and sham-controlled trial undertaken by 11 sites in six different countries. Participants were randomized into one of four conditions with different combinations of exercise training and cognitive rehabilitation including respective sham conditions. The analysis focuses primarily on VO2peak change for the pooled exercise training intervention conditions compared with the pooled sham exercise control conditions. Results Waterfall plots for change in VO2peak suggested greater heterogeneity with exercise training than sham, and the proportions of difference in VO2peak change (i.e. improvement/worsening) were significantly different between exercise training and sham conditions(p