Multiple sclerosis (MS) is an immune-mediated disease characterized by inflammatory demyelination and neurodegeneration within the CNS. This damage of CNS structures leads to deficits of body functions, which, in turn, affect patient activities, such as walking, and participation. The pathogenesis and resulting consequences of MS have been described as concepts within the International Classification of Functioning, Disability and Health (ICF) model--an international standard to describe and measure health and disability. Evidence suggests that exercise training in people with MS has the potential to target and improve many of the components outlined in the ICF model. Although the body of research examining the effects of exercise training on depression, cognition and participatory outcomes is not sufficiently developed, some preliminary evidence is promising. Exercise training is proposed to affect inflammation, neurodegeneration, and CNS structures, but current evidence is limited. In this Review, we discuss evidence from clinical trials that suggests beneficial effects of exercise training on muscle strength, aerobic capacity and walking performance, and on fatigue, gait, balance and quality of life. Issues with current studies and areas of future research are highlighted.