Outcomes from the investigators' recent investigation suggested that a high dosage of challenging physical therapy exercises can result in clinically improvements in the postural balance and walking speed of individuals with MS.

This investigation will evaluate mobility and postural balance improvements in individuals with MS who participate in a therapeutic protocol consisting of activity based exercises, and in individuals with MS that participate in challenging physical therapy protocol.

Background: Outcomes from the investigators' recent exploratory investigation suggested that a high dosage of challenging physical therapy exercises can result in clinically relevant improvements in the postural balance and walking speed of individuals with MS.

Objective: The investigators anticipated that the promising results were due to the novel challenging postural balance and mobility exercises. The purpose of this investigation was to test this notion by evaluating the mobility and postural balance improvements that could be achieved in a cohort of individuals with MS who participated in a therapeutic protocol that consisted of activity based exercises, and a cohort of individuals with MS that participated in the challenging physical therapy protocol.

Inclusion Criteria:

• Definitive diagnosis of multiple sclerosis
• Kurtzke Expanded Disability Status of 3.0 - 6.5
• Able to walk on a treadmill at a minimum of 0.5 miles per hour while holding onto handrails
• Cognitively and emotionally competent
• A Mini-Mental State Examination score > 21
• Composite score on the computerized Sensory Organization Test of < 70

Exclusion Criteria:

• Documented MS-related relapse in the previous 6 months
• Major MS-specific medication changes within the previous 3 months
• Presence of another major co-morbidity such as neurological disorders, uncontrolled pain, hypertension, and diabetes