Exercise Can Cut Coronary Artery Disease Risk For Some With Multiple Sclerosis

Multiple sclerosis (MS) is a degenerative disease affecting the central nervous system of 400,000 Americans with 200 more diagnosed each week. The disease causes reduced nerve function and consequently a variety of symptoms. The most commonly reported symptoms include muscle weakness, spasticity, excess fatigue and depression, which often results in a vicious cycle of reduced mobility and decreased physical activity. Reduced activity level predisposes people with MS to be at increased risk for secondary diseases such as diabetes, osteoporosis and coronary artery disease (CAD).

In an effort to improve the health status of those with MS, a team of researchers worked with individuals diagnosed with mild to moderate disability in an eight week aerobic cycling regimen. The investigators found that people with MS improved their aerobic fitness and reduced their level of CAD risk.

The Study: Summary of Methodology

Eleven MS patients and 11 matched controls (age, sex, body mass index) participated in the study. MS patients were clinically stable and had mild to moderate disability. All volunteers (MS and control subjects) had physician clearance and met specific inclusion/exclusion criteria.

Once enrolled, subjects participated in an eight week supervised aerobic cycling exercise protocol wherein they exercised three days per week. Each exercise session consisted of a three minute warm up at a self-assessed comfortable speed followed by 30 minutes of cycle ergometry (continuous or intermitant) at 60 percent of VO2peak, consistent with the American College of Sports Medicine (ACSM) guidelines for improving health and fitness.

Subjects were assessed for CAD risk before and after the exercise intervention, according to the guidelines of the American Heart Association. Serum samples were obtained the morning after a 12-hour fast, 48 hours before the first and final exercise session of the training program. Enzymatic colorimetric methods were used to analyze serum total cholesterol, high-density and low-density lipoprotein cholesterol, triglycerides and glucose. Anthropometric (body weight, BMI, body fat percentage) measures and blood pressure were also taken at the same time.

Results

The researchers noted that:

• following the intervention, aerobic fitness improved by 10 percent in MS subjects (Pre: 2.2 ± 0.4 L/min; Post: 2.5 ± 0.4) and 14 percent in controls (Pre: 2.4 ± 1.0 L/min; Post: 2.8 ± 1.0), respectively;
• baseline assessment of CAD risk factors showed that the MS subjects had significantly higher circulating levels of triglyceride (MS: 5.0 ± 2.2 mmol/L; Control: 1.2 ± 0.05) and total glucose (MS: 7.1 ± 1.1 mmol/L; Control: 6.6 ± 0.5) compared to the control group;
• after completion of 24 total cycling sessions, MS subjects showed significant reductions in percent body fat, triglycerides and resting diastolic blood pressure. Specifically, there was a 6 percent decrease in percent body fat (pre: 29.6 ± 5.8 percent; post: 27.9 ± 7.6), a 23 percent decrease in triglycerides (pre: 7.75 ± 2.2 mmol/L; post: 5.80 ± 1.8) while diastolic blood pressure dropped 5 mmHg (pre: 80.7 ± 11.1 mmHg; post: 75.0 ± 8.1). Relative improvements in the number of risk factors were observed in 7 of 11 MS participants; and
• the control subjects showed significant decrease in fasting glucose (pre: 6.6 ± 0.5 mmol/L; post: 5.9 ± 0.4). Additionally, four of 11 subjects reduced their relative CAD risk by at least one risk factor.

Discussion/Conclusions

The results of this study support earlier work done by this research team, which showed exercise was associated with reduced individual CAD risk factors among resistance trained MS subjects. The results suggest that people with mild to moderate MS are capable of improving their aerobic fitness to levels similar to their non-MS counterparts. Thus, while physical inactivity may predispose MS patients to have increased CAD risk, MS-related symptoms do not preclude this group from potentially reducing their risk factors through exercise.

Physiology is the study of how molecules, cells, tissues and organs function to create health or disease. The American Physiological Society (APS) has been an integral part of the scientific discovery process since it was established in 1887.

Reference: These findings are drawn from a study entitled Aerobic Exercise Influence on Coronary Artery Disease Risk Factors in Multiple Sclerosis. It was conducted by Darpan Patel, Vanessa Castellano, Sean McCoy, Ashley Blazina and Lesley White, all of the University of Florida, Department of Applied Physiology and Kinesiology, Gainesville, FL. Patel will present the team's findings at the 120th annual meeting of the American Physiological Society, being held as part of the Experimental Biology conference (EB '07).