Metabolic syndrome (MetS) is a group of cardiovascular disease risk factors that occur together, increasing one’s risk for health consequences such coronary artery disease, stroke, and diabetes (2). MetS is diagnosed by a physician identifying at least three of five criteria: increased waist circumference; elevated blood pressure, blood glucose, or triglycerides; and low high-density lipoprotein cholesterol (HDL-C). Criteria by the American Heart Association and National Heart, Lung, and Blood Institute currently are recommended in the United States (15).
The defining criteria are:
- Increased waist circumference:
Men — Equal to or greater than 40 inches (102 cm)
Women — Equal to or greater than 35 inches (88 cm)
Equal to or greater than 150 mg/dL or on pharmacotherapy*
Men — Less than 40 mg/dL or on pharmacotherapy*
Women — Less than 50 mg/dL or on pharmacotherapy*
Equal to or greater than 130/85 mmHg or on pharmacotherapy*
- Elevated fasting glucose:
Equal to or greater than 100 mg/dL or on pharmacotherapy*
An unhealthy lifestyle, including inadequate amounts of physical activity, poor diet, and weight gain, plays a significant role in the development of MetS. Sufficient amounts of physical activity and exercise, including resistance training (RT), can play a major role in the prevention and management of MetS (2,12,25).
IMPACT OF RESISTANCE TRAINING
Recently, there has been more attention and research given to the effects RT has on various metabolic and cardiac diseases. Although this article focuses on RT, exercise professionals should remember that aerobic exercise plays an essential role in the prevention and management of MetS. It would be prudent to perform both aerobic exercise and RT in an attempt to prevent or manage MetS. RT can have a significant effect on some MetS risk factors and should be part of an exercise program designed for managing MetS (25). Recent evidence indicated that RT performed at least 2 days per week can reduce the risk and prevalence of MetS and its individual components in U.S. adults (11,12).
Numerous studies have reported that RT can improve glycemic control (8,9,10,21). In fact, a recent study showed that 10 weeks of RT was associated with better glycemic control in adults with Type 2 diabetes compared with an aerobic (treadmill) exercise group (8).
There have been improvements seen in total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides from RT (17,21). A significant reduction in LDL-C was observed in women who participated in a 16-week program combining caloric restriction and RT compared with women randomized into a caloric restriction-only group or control group (17). However, results from studies examining RT and its effects on blood lipids (e.g., increases in HDL-C) have reported inconsistent findings (14). RT has been shown to decrease both resting and ambulatory blood pressure in individuals with hypertension (20,22). A meta-analysis by Kelley and Kelley (18) indicates that regular RT can reduce resting systolic blood pressure by approximately 2% and resting diastolic blood pressure by approximately 4%. Recent findings indicate that adults engaging in RT at least twice weekly may have lower odds of developing prehypertension (12).
Although RT should not be the emphasis of an exercise program designed for weight loss, RT has an important role with managing abdominal obesity. RT, performed twice weekly, without a weight loss diet, has been shown to improve insulin sensitivity and fasting glycemia and decrease central adiposity in older men with Type 2 diabetes (16). A meta-analysis indicated that RT can have a positive effect on reducing abdominal and total adiposity in persons with abnormal glucose metabolism (25). It is important to remember that RT expends calories and can result in increases in lean body mass, increasing resting metabolic rate (3).
RESISTANCE TRAINING PROGRAMMING
Although there are no specific RT programming guidelines (e.g., sets, reps, exercises) for MetS as a whole at the present time, RT modifications for the specific components of MetS should be considered. When examining these components, prehypertension or hypertension would require the most modifications to keep the person safe during RT. Factors that affect the blood pressure response during RT include load, repetitions, repetition speed, rest periods, sets, and total volume of muscle mass used (24). The exercise professional should consider the following modifications when prehypertension or hypertension is present:
- Monitor blood pressure before and after each session; exercise pressures (e.g., leg press) should be measured as well.
- Know the blood pressure limits: absolute contraindication,180/110 mmHg at rest; relative contraindication, 160/100 mmHg at rest (check with physician); maintain exercise blood pressure <220/<105 mmHg (2,26).
- Ensure medication compliance.
- Start with a light initial load (30% to 40% 1-rep maximum (1-RM) for the upper body and 50% to 60% 1-RM for the lower body), maintain intensity between 11 and 13 on the Borg Category Scale; progress as tolerated (26).
- Use 8 to 10 submaximal repetitions per set; use fast but controlled repetition speeds (e.g., 1-second concentric and 1-second eccentric) (19); if prehypertension or hypertension is not present, higher repetitions may be warranted based on the goals and needs of the person.
- Use rest periods of 60 to 90 seconds to allow blood pressure to return to baseline or near baseline levels (19).
- If necessary to maintain a controlled exercise blood pressure, use one-limb exercises, especially with large muscle mass exercises (e.g., leg press).
There are no specific RT programming modifications for dyslipidemia. However, the exercise professional should ask the person routinely if he or she is experiencing muscle pain or diminished strength, which can be a side effect of statin medications (muscle myopathy) (2). Individuals should be referred to their physician when excessive or consistent muscle pain is present.
Abdominal obesity or obesity may require a few RT programming modifications. These individuals may not fit into some weight machines properly or comfortably. In these situations, large-framed weight machines (if available) or free weights will be a better choice. If muscular strength is very poor, start with elastic bands or tubes, very light dumbbells, or modified calisthenics (e.g., wall push-ups). Osteoarthritis is common with overweight or obese persons, and arthritic weight-bearing joints may require RT modifications (e.g., reduced range of motion, low volume initially). Progression should occur based on how the arthritic joints are tolerating RT (e.g., how painful the joints feel).
Impaired fasting glucose and Type 2 diabetes present some concerns that the exercise professional needs to be aware of:
- RT may be contraindicated in persons with diabetes who have ulcerations and wound infections (with peripheral neuropathy) and retinal detachment (in persons with retinopathy) (2,7).
- Use caution if blood glucose exceeds 300 mg/dL without ketones (2,13). The risk of hypoglycemia increases in individuals taking insulin or oral hypoglycemic agents with preexercise blood glucose levels of less than 100 mg/dL; in this situation, it is advised to ingest a snack with at least 15 g of carbohydrates (with some protein and fat) before exercising (1).
- Hypoglycemia can be prevented by having the individual check his or her blood glucose before exercise, every 30 minutes during exercise, and after exercise.
- Evening exercise can cause hypoglycemia during sleep and should be avoided if possible.
- Know the common signs and symptoms of hypoglycemia: shakiness, weakness, abnormal sweating, nervousness and anxiety, tingling of the mouth and fingers and hunger, headache, visual disturbance(s), mental dullness, confusion, amnesia, and, in severe cases, seizures and coma (2).
- Have high glycemic index foods and snacks such as fruit juice available to avoid or reverse exercise-induced hypoglycemia.
Mrs. J is a sedentary 48-year-old administrative secretary and a married mother of two college-aged boys. Her physician has cleared her to work with you to develop a comprehensive exercise program. She was diagnosed 2 years ago as having hypertension and has dyslipidemia and impaired fasting glucose (MetS). She states wanting to take her 6-month-old Labrador retriever puppy Bailey on long walks at the beach but “I cannot last for more than 10 minutes without stopping because I get so tired and my muscles feel weak.” She achieved eight metabolic equivalents (8 METs) during a maximal treadmill stress test (Bruce Protocol), a maximal heart rate of 155 BPM (90% of age-predicted maximal heart rate), and a rating of perceived exertion (RPE) of 18 out of 20 on the Borg Scale. Her peak blood pressure was 180/80 mmHg, and the treadmill stress test was stopped because of general fatigue. She reported no signs or symptoms of exercise intolerance or physical discomfort and displayed no electrocardiographic abnormalities. Her physician considered the test to be “normal” and “unremarkable.” Her current medications include atenolol, lisinopril, metformin, and atorvastatin.
Additional tests revealed the following results:
- Height: 5′2″ (157.5 cm)
- Weight: 165 lbs (75 kg)
- Waist circumference: 36″ (91.4 cm)
- Body mass index: 30 kg/m2
- Total cholesterol: 260 mg/dL
- HDL-C: 45 mg/dL
- LDL-C: 181 mg/dL
- Triglycerides: 170 mg/dL
- Fasting glucose: 96 mg/dL
- Resting blood pressure: 118/70 mmHg
1-RM bench press: 90 lbs (40th percentile): She reported an RPE of 18 out of 20
1-RM leg press: 180 lbs (30th percentile): She reported an RPE of 18 out of 20
Mrs. J will use her son’s treadmill and stationary bicycle for 10 minutes twice each day. She will exercise 5 days a week. Her initial goal will be to perform between 30 and 60 minutes of moderate (40% to <60% heart rate reserve or V˙O2R) exercise at least (150 to 300 minutes per week).
This initial exercise volume goal will be as tolerated and progressed according to how she handles the initial exercise sessions. Ultimately, she wants to incorporate treadmill walking, stationary cycling, and walking Bailey for a total of 60 to 90 minutes daily. To avoid injuries, she will increase her exercise time gradually and alternate (cross train) her daily exercise modes by adding an additional exercise mode like the elliptical trainer and the recumbent arm and leg ergometer (i.e., NuStep).
Mrs. J also will participate in a twice-weekly RT program as an adjunct to her endurance training to help improve her muscular strength and endurance and overall physical function. Mrs. J is sedentary and deconditioned. Initially, she will perform one (1) set of 8 to 12 exercises per session that use all major muscle groups. She will use weights that she can lift for 8 to 10 submaximal repetitions with proper technique and control. She will use her son’s multistation selectorized RT machine. After completing an exercise set, she will rest for 60 seconds and then begin a set of another exercise and continue this process until all prescribed exercises in her circuit are completed (see below). Her initial RT circuit will include:
- Seated leg press
- Seated chest press
- Seated leg extension
- Seated row (with chest pad support)
- Seated leg curl
- Shoulder press
- Latissimus pull-downs
- Back extension
- Abdominal crunch
She will have her blood pressure taken before, during, and after her workout sessions. She will exercise at an RPE of 11 to 13 out of 20. She has been informed to maintain adequate hydration, report any symptoms of either muscle pain or weakness, and avoid exercising too close to going to bed at night. See table for a breakdown of the RT variables.
It is well supported that RT, particularly when combined with aerobic exercise, can help manage MetS. Although aerobic activities should be emphasized, RT also should be considered when there are no absolute contraindications. More research is needed to determine specific effects RT may have on MetS and to potentially develop specific RT guidelines for MetS. However, research indicates that regular RT has beneficial effects on MetS and should be a part of an exercise program for managing or preventing MetS.
BRIDGING THE GAP
Metabolic syndrome (MetS) is a clustering of risk factors for various cardiovascular diseases. Regular exercise and physical activity can have a significant impact on MetS. Resistance training, independent of aerobic exercise, can impact the components of MetS positively and should be included in a regular exercise program for someone who has or is at risk for MetS.
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*Taking physician-prescribed medication(s) to treat the health condition.