Effects of aerobic and strength exercise on motor fatigue in men and women with multiple sclerosis: a randomized controlled trial

OBJECTIVE: To investigate the effects of aerobic and strength exercise on motor fatigue of knee flexor and extensor muscles in subjects with multiple sclerosis (MS). DESIGN: A randomized controlled trial. SETTING: At Masku Neurological Rehabilitation Centre, Masku, and the Social Insurance Institution, Research Department, Turku, Finland. SUBJECTS: Ninety-five MS patients with mild to moderate disability were randomized into exercise group (n =47) and a control group (n =48). INTERVENTION: Participants in the exercise group attended in a supervised exercise period of three weeks, which was followed by a home exercise programme lasting for 23 weeks. Patients in the control group continued with their normal living. OUTCOME MEASURES: Motor fatigue of knee flexor and extensor muscles was measured during a static 30-s maximal sustained muscle contraction. The decline in force (Nm) during the 30 s was recorded, and a fatigue index (FI) was calculated. Subjective fatigue was measured by using the Fatigue Severity Scale (FSS). The Ambulatory Fatigue Index (AFI) was calculated on the basis of a 500-m walking test. Assessment took place at baseline, at the third week (not for the control group) and at the 26th week. All outcome variables were analysed, men and women together, and some interesting contrasts were analysed by gender. RESULTS: Associations were observed with changes in extension FI and Expanded Disability Status Scale (EDSS) score and mean extension torque (Nm), but not with changes in FI and aerobic or strength exercise activity, mean AFI, mean FSS or in mean knee flexion torque. AFI was decreased in all subject groups (p =0.007). Motor fatigue was reduced in knee flexion (p=0.0014) and extension (ns) among female but not in male exercisers after six months of exercise. The exercise activity of women was 25% higher than that of the men. CONCLUSIONS: Six months of exercise reduced motor fatigue in women, but not in men.