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Simvastatin Can Reduce the Benefits of Exercise in Active Adults

A study found that 40mg of simvastatin reduced the cardiorespiratory fitness of adults with metabolic syndrome….

Metabolic syndrome is increasing in prevalence among overweight and obese adults in the United States. Characterized by hypertension, central adiposity, dyslipidemia and increasing insulin resistance, metabolic syndrome is associated with the development of type 2 diabetes and cardiovascular disease. Therapeutic lifestyle changes are the first line of therapy for the treatment of metabolic syndrome: however, the use of statins for the management of this syndrome has become commonly practiced. A recent study out of the University of Missouri may make some clinicians reconsider the addition of statin pharmacotherapy to those individuals trying to manage metabolic syndrome through increased exercise.

Mikus and colleagues conducted a randomized, controlled trial to study the effects of simvastatin in combination with exercise on changes in cardiorespiratory fitness and skeletal muscle activity. Statins are generally well tolerated by most patients but documented adverse effects including skeletal muscle cramping and myalgia have led this research group to determine if simvastatin impairs exercise tolerance.

Forty-one adults, ages 25-59, enrolled in a 12 week supervised exercised training program. Additional inclusion criteria included a BMI >26 and less than 39, sedentary lifestyle ( less than 30min exercise per week) and 2 metabolic syndrome risk factors defined according to National Cholesterol Education Panel Adult Treatment Panel III criteria. Participants were randomly assigned to a group receiving 40mg of simvastatin plus aerobic training, or aerobic training alone. Thirty-seven out of the initial forty-one subjects completed the study. The primary outcomes measured were cardiorespiratory fitness and the amount of citrate synthase enzyme activity in the skeletal muscle, vastus lateralis.

The researchers found that participants enrolled in the exercise-only group saw an increase in their cardiorespiratory fitness by 10%. Participants with the combination of simvastatin and exercise only saw an increase in cardiorespiratory fitness by 1.5%. Analysis of expired gases and peak oxygen consumption was used to define cardiorespiratory fitness.

In a similar trend, skeletal muscle citrate synthase activity increased by 13% in participants of the exercise group. Those subjects receiving simvastatin had a 4.5% decrease in citrate synthase activity.

Co-author John Thyfault, an associate professor of nutrition and exercise physiology, reported, "Daily physical activity is needed to maintain or improve fitness, and thus improve health outcomes. However, if patients start exercising and taking statins at the same time, it seems that statins block the ability of exercise to improve their fitness levels." Thyfault expressed concern that from this date cardiologist should closely weigh the benefits or risks of statin therapy in patients adhering to fitness training.

Further studies are required to determine the effects of the other statins on cardiorespiratory fitness as well as different strengths of these drugs before a definitive conclusion can be made.

Simvastatin impairs exercise training adaptations. Journal of the American College of Cardiology, 2013; DOI:10.1016/j.jacc.2013.02.074