Exercise as it relates to Disease/Aerobic exercise and relapsing Multiple Sclerosis

Background
Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system. The onset of Multiple Sclerosis usually occurs between the ages of 20 and 50.

Diagnosis:The process involves the use of MRI, Cerebrospinal Fluid Analysis and tests of cognitive function, eyesight and muscular strength. The clinical course that we will focus on is Relapsing-Remitting MS. This involves periods where symptoms will flare-up interspersed with periods where no, or very mild symptoms are present. Symptoms will not necessarily get worse over time, however flare-up periods may increase in length as the disease progresses.

Aetiology:The cause of MS remains vastly unknown, however several links to genetics, the environment and infectious agents have been established.

Genetics: Several 'risk alleles' have been identified within the human genome. Presence of these alleles increases an individual's susceptibility to MS. Links to ethnicity and gender have also been observed, with those of Caucasian decent being at higher risk. New studies have also shown that females are twice as likely to present with MS establishing a strong genetic link.[1]

Environmental: Prevalence of MS increases laterally in both directions from the equator. In addition, the amount of sunlight available plays a role, and definite link to vitamin D deficiency and increased susceptibility has been found.

Infectious Agents: Microbial agents such as the Epstein-Barr virus and Herpes simplex virus have been linked to MS, mainly due to an increased infection rate in MS sufferers. However these agents cannot be directly linked to the disease, as Koch's Postulates of disease have not been met.

Pathophysiology:MS is characterized by demylination of nerves in the CNS and formation of sclerose which result from scarring caused by demylination. This causes a disruption in the neuronal pathways to the muscle. This results in spacticity, poor motor control, muscular weakness, fatigue, thermosensitivity, poor balance and impaired cognitive function amongst many other symptoms.

Difficulties of Exercise
There are many variables of MS disease that hinder a patients ability to exercise. These factors may also prevent the patient from gaining the full benefits of exercise.

Progression MS disease is both variable and progressive. The patients disability may change or worsen at any given time. This provides limitations to maintaining a regular exercise routine as the patients symptoms are forever changing. [6]

Heterogeneity

MS lesions occur to any myelinated structure within the CNS. This results in there being a diverse range of disabilities affecting patients. Consequently, a standard prescription of exercise is unable to be produced. A detailed assessment of the patient is needed before any exercise is prescribed. The diversity of the disease also limits the credibility of any research performed.[6]

Fatigue

MS patients experience higher degrees of fatigue than the average person. Higher degrees of fatigue influence their ability to exercise. This also limits any benefits incurred from an exercise program.[5]

Thermosensitivity

MS patients experience a rise in core temperature. This often leads to an increase of neurological symptoms, further hindering the patients ability to exercise. Cooling techniques may offer an improved ability to exercise, allowing the patient to achieve superior exercise gains.[6]

Ataxia

MS patients may experience primary ataxia due to damage of the motor tracts, reducing the patients ability to exercise. Secondary ataxia may result from the patients reluctance to exercise. This secondary form may be partially prevented by exercise prescription.[6]

MS and Aerobic Exercise
Various studies have been performed into the effects of aerobic exercise upon MS patients. Most confer that MS patients respond to exercise in a similar way to disease free individuals. Some of the current known benefits of aerobic exercise upon MS patients include:

– Improvement in controlling MS symptoms – Reduced systemic fatigue – Improved mood – Improved ability to perform daily tasks – Decreased risk of obesity, heart disease, diabetes and osteoporosis – Increased VO2 and functional capacity – Increased muscle strength and endurance – Improved lung function [5]

Recommendations
Several aspects of the course of relapsing MS need to be considered when prescribing exercise for an MS sufferer:

Progression & Heterogeneity: As symptoms of MS differ and progress at different rates in each individual, regular assessment of fitness and physical capability must occur. This would involve V0 2, muscular strength and cognitive function testing, as these aspects would be particularly variable in MS sufferers due to the pathophysiology of the disease. This would enable the prescriber to determine work loads, intensity and complexity of the tasks to be performed.[5]

Fatigue To combat the faster fatigue rate in MS sufferers, shorter bouts of exercise should be performed. Overload during sessions should be followed by a longer period of rest or low intensity exercise in order to fully recover. Prolonged exercise and activities that involve repetitive action of a muscle group should be avoided to minimise the risk of overtraining. Variety during training sessions should be encouraged to prolong the onset of fatigue, maintain motivation and ensure that exercise adaptations are systematic.

Thermosensitivity Aerobic exercise is the most likely to cause an increase in core temperature during exercise. Pre-cooling can overcome this, and has been shown to be effective in MS patients. Another mechanism to combat this is aquatic exercising, such as lap swimming and aqua aerobics.[6]

Ataxia Shorter periods of repetitive aerobic exercise should be done, such as rowing, cycling and running. This will allow aerobic adaptation to occur and muscular strength and endurance to increase, negating most of the ataxia due to MS. [5]