The Impact of Training on Sitting Time and Brain Volumes in Multiple Sclerosis.

All participants will perform a home-based supervised exercise training program. Participants will receive weekly training instructions using a smartphone-based heart rate monitor application (Polar® app). Training sessions will involve running and the design of the training program will be based on linear periodization, where aerobic capacity is built firstly through a period of high-volume/low-intensity training before the proportion of high-intensity training is increased. The total duration of the exercise program will be 12 months with three weekly training sessions. Training progression will be dependent on initial VO2max values and running experience. VO2max classification is based on reference values described in V.H. Heyward, Advanced Fitness Assessment and Exercise Prescription, Fifth Edition, 2006, Champaign, IL: Human Kinetics.