Metabolic Syndrome: Exercise Is KEY to Prevention
Stephen A. Black
Fortunately, it is becoming increasingly clear that physical activity does not need to be highly structured or regimented to yield health benefits. Furthermore, the threshold of intensity necessary for the health benefits of exercise is lower than previously thought. The Centers for Disease Control and Prevention suggests that people should accumulate at least 30 minutes of moderate-intensity physical activity on most, preferably all, days of the week.
Despite this overwhelming data, only 22 percent of adult Americans are currently active enough to derive health benefits, and 25 percent are completely sedentary. Only about one-half of U.S. young people (ages 12 to 21) regularly participate in vigorous physical
Within this epidemic has emerged a new classification of disorder that needs immediate attention. Metabolic syndrome, also called insulin resistance syndrome or syndrome X, is a cluster of risk factors that is responsible for much of the excess cardiovascular disease morbidity among the overweight and obese.
The major characteristics of metabolic syndrome include insulin resistance, abdominal obesity, elevated blood pressure and lipid abnormalities (i.e., elevated levels of triglycerides and low levels of high-density lipoprotein cholesterol). Each component of the syndrome has been associated with an increased risk of cardiovascular disease.
Criteria for metabolic syndrome, according to the World Health Organization (WHO), include the following:
* Abdominal obesity: a waist circumference greater that 40 inches for men and women
* Body mass index (BMI) greater that 30kg/m2
* Triglycerides greater than 150mg/dl
* Blood pressure greater than 140/90mm Hg
* A high fasting glucose at 110mg/dl
The cause for metabolic syndrome has not been definitively established. One hypothesis presumes the primary cause is insulin resistance. Insulin resistance correlates with visceral fat measured by circumference, or waist-to-hip ratio. The link between insulin resistance and cardiovascular disease probably is the result of vascular damage and plaque formation.
The second hypothesis blames hormonal changes for the development of abdominal obesity. Studies demonstrate that people with elevated levels of cortisol (caused by chronic stress) develop abdominal obesity, insulin resistance and lipid abnormalities. This results in cardiovascular decay.
Based on clinical trials, aggressive management of the individual components of the syndrome should make it possible to prevent or delay the onset of diabetes, hypertension and cardiovascular disease. All individuals with the syndrome or risk factors to it should be encouraged to change their diet and exercise habits as primary treatment. Weight loss improves all aspects of metabolic syndrome, as well as reducing the risk of cardiovascular disease. Exercise and dietary changes that lower blood pressure and improve lipid levels will improve insulin resistance, even in the absence of weight loss.
Skeletal muscle is the most insulin-sensitive tissue in the body and, therefore, a primary target for affecting insulin resistance. Physical activity has been shown to reduce skeletal muscle lipid levels and insulin resistance, regardless of BMI. The effect of exercise on insulin sensitivity is evident for 24 to 48 hours, and disappears within three to five days. Thus, regular physical activity should be a part of the lifestyle plan. The goal is to find a level of activity that can be accomplished over the long term. A combination of resistance and aerobic exercise is best, but any activity is better than none. Manipulation of duration and intensity -- starting according to the person's prior level of activity -- will provide a safe and effective program with minimal attrition. Success has been achieved through walking and low-weight resistance activities. Circuit training is of great benefit to these individuals. Studies have shown that walking or light jogging for one hour per day will produce significant losses of abdominal fat in men without caloric restriction.
Suggested treatment strategies for reducing the risk of cardiovascular disease and diabetes include the following:
* Lower clients' LDL cholesterol to less than 100mg/dl.
* Institute weight control; work to lower clients' BMI to less than 30 and, eventually, less than 25.
* Increase clients' physical activity.
Cardio exercise should be performed for 30 to 40 minutes a day, at least three, and preferably five, times each week. The cardio exercise of your clients' choice is best. Make them comfortable and accommodate their needs as much as possible. Consider aquatic activities followed by a progressive, land-based cardio choice (recumbent to sitting to standing supported to standing unsupported).
Strength training -- major muscle groups first -- should include light resistance and high reps. Consider selectorized supported equipment first, and have clients follow a similar progression to that of the cardio program. Remember, these individuals may be severely deconditioned.
The primary goals of dietary change for metabolic syndrome are to reduce the risk of cardiovascular disease and diabetes. Evidence from one large and one small clinical trial show that a low-sodium diet helps to maintain lower blood pressure. Results from clinical trials of low-fat diets, in which participants were involved for more than two years, showed significant reductions in the rate of cardiovascular events.
According to the Dietary Approaches to Stop Hypertension (DASH) study, participants who consumed a diet low in saturated fat and high in carbohydrates experienced a significant reduction in blood pressure, even without weight reduction. The DASH diet emphasizes fruits, vegetables, low-fat dairy foods, whole grains, poultry, fish and nuts, while reducing saturated fats, red meat, sweets and sugar-containing beverages. Reducing sodium intake can further reduce blood pressure, or prevent the increase in blood pressure that may accompany aging.
The Coronary Artery Risk Development in Young Adults study demonstrated that consumption of dairy products was associated with a significantly reduced risk of metabolic syndrome.
The long-term effects of low-carbohydrate diets have not been studied adequately, but, in the short-term, these diets have been shown to lower triglyceride levels, raise HDL-cholesterol levels and reduce body weight. An alternative to lowering consumption of all carbohydrates is to replace high-glycemic-index foods with less refined lower-glycemic-index foods that contain more fiber.
The goal is to modify clients' diet to reduce sodium, thus reducing blood pressure, and have them reduce triglyceride levels to below 200mg/dl.
Clearly, prevention is the chosen route when dealing with metabolic syndrome. The health and wellness industry is the prime candidate to assist individuals in the understanding of metabolic syndrome, and to assist in the development of lifestyle strategies to prevent or treat the condition. A member-centered methodology, accompanied by supportive facility services, will make the intervention more effective. Effective staff members can assess members' knowledge about the relationship of their lifestyle to their health, then provide a clear message about the importance of diet and exercise for their specific problem. The identification of short- and long-term goals, as well as barriers to change, are helpful in this scenario. Finding methods that fit with members' lifestyles will minimize disruption in their lives, and improve adherence and compliance. Keeping it simple and building on a solid foundation of exercise and nutritional counseling will provide long-term success.
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Ithaca College Athletics and Events Center