For HDL Cholesterol, Fitness Trumps Weight
There’s no question that high levels of HDL cholesterol seem to protect against heart disease. Rather than depositing fat into the blood vessels like LDL cholesterol, HDL appears to carry cholesterol away from blood vessels to the liver. From there, the liver processes it for removal from the body.
However, adequate levels of HDL cholesterol may not be enough. Several recent studies have suggested that many cases of heart disease occur in people with normal levels of HDL cholesterol. Consequently, some researchers believe that HDL cholesterol may not work well even if people have adequate amounts in their blood. This also may cause the cholesterol to fail to fulfill other important functions, such as reducing inflammation and acting as an antioxidant.
Because exercise can protect against heart disease in various ways, Christian K. Roberts, PhD, and colleagues at UCLA tested whether HDL cholesterol in men who weight trained regularly behaved in a more healthful way than HDL cholesterol in sedentary men. They found that the men who didn’t exercise were more likely than those who weight trained to have dysfunctional HDL cholesterol. Having faulty HDL cholesterol was associated with numerous risk factors for heart disease, including high triglycerides and a higher trunk fat mass. This finding held true regardless of the men’s weight, which suggests that maintaining a “healthy” weight isn’t as important for healthy cholesterol function as being active by regularly performing strength training.
The researchers, whose study appeared in the Journal of Applied Physiology, worked with 90 men between the ages of 18 and 30 who already had established exercise habits. They separated the participants into three groups: lean men who weight trained at least four times each week, overweight men who weight trained at least four times each week, and overweight men who had no structured exercise regimen. The researchers took basic physical measurements from the volunteers, including height and weight, waist circumference, blood pressure, and body composition. They tested the volunteers’ muscle strength and carotid artery thickness and also took blood samples. The researchers analyzed the samples for a variety of different molecules present, including cholesterol; insulin; various markers for heart disease, including triglycerides and C-reactive protein; and sex hormones. They also checked the HDL cholesterol to see how well it functioned as an antioxidant, a sign of how well the molecules work in general.
The study authors found that HDL cholesterol functioned better in the participants who had a regular weight-lifting program, regardless of their weight, and overweight exercisers’ HDL cholesterol has similar effectiveness as an antioxidant as the lean exercisers’ HDL cholesterol. Both groups’ HDL cholesterol performed significantly better than those who didn’t exercise.
These findings suggest that regular weight training may improve HDL cholesterol function and protect against heart disease, even in those who remain overweight. Although indices of weight were associated with HDL cholesterol function, differences in fitness, the authors say, may be a better measure of who has healthier functioning HDL cholesterol and therefore who’s at risk of heart disease.
“The role of obesity in the risk of coronary heart disease may indeed be largely accounted for by differences in fitness,” the authors say.
Source: American Physiological Society