Exercise and Hyperlipidemia
Research supports that higher HDL-C reduces the risk of CHD.80 The reason for a focus on HDL-C levels is based on the idea that CVD risk can be reduced by incorporating lifestyle changes, such as regular physical activity and a diet high in fruits and vegetables. Large-population studies have shown HDL-C to be positively associated with physical activity.81,82
The Lipid Research Clinics Coronary Primary Prevention Trial took more than 7000 men who had hyperlipidemia and categorized them by amount of physical activity they received in and out of work and the frequency of exercise or physical labor. Once they were rated on their physical work and leisure-time physical activities, they were placed into 3 activity groups (low, moderate, and high). Results indicated that physical activity levels were a significant predictor of HDL-C and triglyceride levels, even after controlling for smoking, alcohol use, and total cholesterol.43
A single 30-minute exercise session/week proved to be helpful in lowering subcutaneous fat and triglycerides and increasing HDL-C in a study of Japanese men.60 The greatest benefit was observed in the most active group (30 minutes for > 3 days/week), but compared to the sedentary group that did not exercise, it was clear that even minimal activity can positively impact CVD risk factors.60 Although some evidence was found regarding the effectiveness of physical activity on cholesterol levels, more epidemiological research regarding the best intensity and duration needed to change HDL-C and triglyceride levels would help solidify the physical activity recommendation.
Exercise and Weight Loss
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The ACSM guidelines offered an extraordinary amount of health benefits, but they were not established to cause a large amount of weight loss. Instead, the 150 minutes/week of moderate physical activity might be enough activity to prevent weight gain. The reason for this is that the health benefits of physical activity are independent of weight loss, meaning that one does not have to lose weight to lower the risk of chronic disease. One has to be physically active. The media presents a picture of physical activity and weight loss that is sometimes exaggerated. Magazine articles, fitness websites, exercise equipment, infomercials, and common gym talk give people the idea that the purpose of exercise is to lose weight. The message should be that physical activity will help keep and improve health.
Although exercise is seen by many as the pathway to weight loss, it can be argued that this expectation is part of the physical inactivity problem because many people become discouraged by unsuccessful attempts to lose weight by increasing exercise. These same people are discouraged to continue with daily exercise because it is not accomplishing their goal for beginning physical activity. Evidence shows that as many as 50% of those who begin an exercise program will drop their exercise routine within 6 months.83 To receive the most protection from physical activity, regular sessions throughout the lifespan are needed. However, if a majority of people believe that a physical activity program will make them lose weight, they will likely be discouraged and stop before realizing the health benefits. With a narrow focus on weight loss, an individual can lose sight of the more significant and true benefits presented in this chapter.
People seeking weight loss through physical activity need to understand that fitness may have a greater impact on their health. A study of older adults (N = 2603, > 60 years old) investigated the effects of cardiovascular fitness and central obesity on mortality. Researchers separated participants into 5 fitness groups based on their performance on a maximal exercise test. As expected, fitness was inversely related to mortality. The lowest fitness group had the highest death rate. The researchers found that when the data were adjusted for BMI and central obesity, fitness levels were still a significant predictor of mortality regardless of a person’s weight.84
More recently, 44,674 men participated in part of the Cooper Center Longitudinal Study that examined the association of cardiorespiratory fitness, BMI, and heart failure mortality. The men were free of CVD at the start of the study and were placed in the fit or unfit group based on a treadmill test. At the follow-up (average of 19.8 years later), 153 had died from heart failure. Fitness and BMI had a significant impact on heart failure mortality. When the data were adjusted for BMI, the fit group had a lower risk of mortality regardless of normal or overweight status.85 This research underscores the impact of fitness and that increased physical activity is needed to become fit rather than lose weight. Physical activity should be undertaken at a level that overloads the body to improve one’s cardiorespiratory fitness to receive the most benefit.