Cardiorespiratory fitness and moderate-to-vigorous physical activity in older adults with multiple sclerosis

BACKGROUND: Cardiorespiratory fitness (VO2peak) may be a modifiable indicator of health status and well-being in older adults with multiple sclerosis. PURPOSE: We examined differences in VO2peak and moderate-to-vigorous physical activity between older adults with multiple sclerosis and healthy controls, and whether moderate-to-vigorous physical activity accounted for group differences in VO2peak. METHODS: Older adults with multiple sclerosis (n = 31) and healthy controls (n = 29) completed a cardiopulmonary exercise test and wore an accelerometer for measuring moderate-to-vigorous physical activity. The data were analyzed using the Baron and Kenny approach for examining moderate-to-vigorous physical activity as a mediator of group differences in VO2peak. RESULTS: The multiple sclerosis group had significantly lower VO2peak and moderate-to-vigorous physical activity than healthy controls. VO2peak had a large correlation with moderate-to-vigorous physical activity (r = .59). Group initially explained 8% of the variance in VO2peak (β = -0.29). The inclusion of moderate-to-vigorous physical activity accounted for an additional 27% of the variance in VO2peak, but only moderate-to-vigorous physical activity (β = 0.57) was a statistically significant correlate of VO2peak. The effect of Group was attenuated and non-significant with the addition of moderate-to-vigorous physical activity in Step 2 (Group β Step 1 = -0.29, Group β Step 2 = -0.05). CONCLUSIONS: Our results provide initial support for targeting moderate-to-vigorous physical activity as an approach for improving VO2peak in older adults with multiple sclerosis.