Introduction: Multiple sclerosis (MS) is characterized by decreased strength and motor control, and compromised gait function. Reduced walking speed, balance, and fatigue are the cardinal symptoms. In rehabilitation, strength and balance training are commonly used. There is increasing scientific support of strength training for improving walking function. The evidence for balance training remains flawed. It is known that neurological damage in MS leads to increased cognitive processing in the planning of movements, which predisposes fatigue. Since fatigue is also associated with impaired balance, it can be hypothesized that motoric/balance training with an emphasis on cognitive load can affect gait and fatigue.

Purpose: The aim of the study is to determine whether there is a differentiated effect between strength and balance training measured by motor function, strength, balance, and fatigue.

People with MS experience a wide variety of symptoms including impaired muscle strength and balance, fatigue, impaired cognition, depression and spasticity. Of these, impaired balance and severe fatigue are described as two of the most debilitating symptoms leading to limitations in activities such as upright posture and gait. Generally, pharmacological symptomatic treatment has not proven efficient in the treatment of balance problems, fatigue and walking impairments, with the exception that Fampridine has beneficial effects on gait performance in a subgroup of patients. Consequently, non-pharmacological interventions that effectively target these symptoms are warranted.

In the last decade progressive resistance training (PRT) has proven to be one of the promising interventions in patients with MS showing a consistent and positive effect on muscle strength. However, the effect of PRT on functional outcomes are heterogeneous but with promising effects on daily activities such as walking and chair rise. The evidence for a beneficial effect of PRT on balance and postural control is divergent and yet inadequately investigated. Regarding fatigue, a recent Cochrane review reported that one could expect improvements in MS fatigue after exercise interventions, despite methodological flaws in the existing literature, but only few studies evaluating PRT were located.

Another promising intervention is task specific training of motor function that is widely used by physiotherapists in neurorehabilitation. In this study protocol, motor function is limited to gait related functions with a particular focus put on balance and motor control, why the term Balance and Motor Control Training (BMCT) is applied. There is no universally accepted definition of human balance, but balance defined as "the inherent ability of a person to maintain, achieve or restore a specific state of balance and not to fall, with reference to the motor and sensory systems and to the physical properties of the person", is applied in this study.

Effects obtained from BMCT partly result from plastic changes in the nervous system. To induce such effects, repetition of a simple task only has limited efficiency in order to improve performance. Once a task has been learned to a certain level, further practice of the same task will not be accompanied by further induction of plasticity and little is therefore gained by continued practice of the task. To provide challenges that ensures continued learning, training exercises have to progress from simple movement trajectories to more complex movements, that also incorporates goal setting. Moreover, it has been shown that shaping and variation of tasks in combination with feedback on movement quality is of great importance for the learning outcome. The underlying concept for performing BMCT is, therefore, that improved motor control will optimize the movement strategy, which further leads to improved gait function.

Regarding the effects of BMCT on fatigue, there are diverging results in the literature, but the literature on BMCT for patients with MS is generally of low quality with an inadequate description of interventions, why further studies are warranted.

Interestingly, the principles of task specific training do fundamentally contrast the principles of PRT, that normally consist of monotonous movement patterns performed under heavy loading for a low number of repetitions. Consequently, studies comparing the effects of BMCT and PRT on gait function would add to the current literature as no studies doing so could be located. Such a comparison would help clarify whether potential effects are overlapping or differentiated and would therefore help guiding future rehabilitation interventions in persons with MS.

The primary objective of this study is, therefore, to investigate and compare the effects of 10 weeks of PRT to BMCT on gait function, balance and fatigue in mobility limited persons with MS.

It is hypothesized that PRT will be superior in improving maximal straight gait speed, whereas BMCT will have a greater impact on balance, fatigue, and more complex walking tasks that include elements of balance and coordination.

Inclusion criteria

• Diagnosed with multiple sclerosis.
• Expanded Disability Status Scale (EDSS) 2.0-6.5 and min. 2.0 in the functional system "pyramidal function".
• Able to walk 100 m.
• Able to manage own transportation in relation to weekly training and tests.
• Six spot step test score > 8 sec. or Timed 25 foot walk > 5 sec.

Exclusion criteria

• Co-morbidity in terms of dementia and alcohol abuse.
• Attack within the last eight weeks.
• Systematic intensive rehabilitation/training within the last three months.
• Adjustment of medication within two months before inclusion. This applies only for medication that affects gait performance and spasticity.