Intermittent Strengthening Results In Improved Leg Raise Function In Persons With MS

Background:  Loss of strength is a common finding in persons with Multiple Sclerosis (MS) and frequently results in diminished function. Although diminished strength  may occur for a variety of reasons in this disease, neurogenic fatigue, a common problem in MS, may be a major reason why strength loss occurs. Fatigue can  prevent persons with MS from performing a sufficient amount of Progressive Resistive Exercises (PRE’s) to improve their strength. If a PRE’s could be performed without the buildup of fatigue in persons with MS, a larger quantity of exercise could be performed, and greater strength gains could be made. 

Objectives: Previous research has shown that intermittent walking can lead to greater distances walked than continuous walking in persons with MS, but the effects of intermittent strengthening has not been studied in this population. The purpose of this study was to examine the use of an intermittent as opposed to continuous strengthening protocol on persons with MS. We hypothesized that patients with MS would be able to perform a greater amount of straight leg raises if they were performed intermittently than if they were performed continuously. If our hypothesis was correct, it would suggest that intermittent training could be used as a means of improving strength in persons with MS who are limited in this activity due to fatigue.

Methods: 28 MS patients (EDSS 1.5-5.5) were recruited from an MS specialty practice. Subjects  performed Straight Leg Raises  (SLR) continuously and intermittently one week apart.  Continuous straight leg raises were performed at the rate of one every 3 seconds, while intermittent straight leg raises were perfomed at the rate of 2 every three seconds, interspersed with 10 second rests. The total number of SLR's performed in each conditon was measured, as well as the the level of fatigue associated with each each type of leg raise.

Results: A significantly greater number of SLR’s were performed intermittently than continuously (114.5 vs 31.85 respectively, p<. 0001), indicating that the subjects found the intermittent SLR’s less fatiguing.

Conclusions:   Performing a sufficiently high volume of training is necessary to improve function, but this is often limited in MS due to neurogenic fatigue. Our study suggests that intermittent training may provide a means by which persons with MS can perform a greater volume of training, and thus realize greater therapeutic gains.