To Lower Triglycerides, a Moderate Workout is Best
Doctors have been saying for years that exercise helps lower cholesterol levels, but surprisingly little effort has been expended on finding out what kind of exercise works best. Now, there's some unexpected evidence. New research on exercise in overweight, sedentary, middle-aged people with elevated cholesterol levels reveals that different types of exercise have vastly different effects on blood lipids, and those effects last for varying lengths of time. More exercise isn't necessarily better, the team found. But none is really, really bad.
Some of the findings come as no surprise: The most vigorous types, who sweated off the caloric equivalent of jogging 20 miles a week for six months, raised their HDL "good" cholesterol levels, and maintained those benefits two weeks after they stopped exercising. A second group, who did the equivalent of jogging 12 miles a week, saw somewhat less improvement. (The exercisers didn't actually run, but rather used treadmills, elliptical trainers, or stationary bicycles, and raised the ramp or increased resistance so that they were working hard.)
What startled researchers was that people who followed a more moderate exercise program, the equivalent of walking 12 miles a week, lowered their triglyceride levels by about 25 percent, twice as much as the hard-core group. And they maintained that benefit for two weeks, while the triglyceride levels of the more vigorous exercisers rose after five days without exercise. High triglycerides are considered a risk factor for metabolic syndrome, which is linked to diabetes and heart disease.
The team was frankly baffled by the big differences. "The good news is that moderate exercise has a lot of benefits," says Cris Slentz, an exercise physiologist at Duke University Medical Center who is the lead author. "On the other hand, vigorous exercise increases cardiovascular fitness." The report, part of an ongoing study on exercise and heart disease, was published in the August Journal of Applied Physiology, and included scientists from Duke and East Carolina University. Slentz imagines a day when doctors will give patients personalized exercise prescriptions, based on their lipid profiles.
If any doubt remained, sitting still is a terrible idea. The folks who were asked to do no added exercise as a control group, didn't just not improve—their health actually deteriorated. Over the six months, their LDL cholesterol levels rose, they gained 2 pounds, and they grew half an inch around the waist. "We think the data shows that exercise is really not optional," says Slentz.
Experts disagree on the right formula to maintain cardiovascular health and reduce the risk of stroke, heart disease, and diabetes. The Centers for Disease Control and Prevention recommends 30 minutes of moderate exercise at least five days a week, while the Institute of Medicine says 60 minutes a day is best. That debate will continue, but meantime anyone willing to get up off the couch has a reasonable goal. Most sedentary people can work their way up to walking 12 miles a week without getting hurt, physiologists say. (The study participants took two to three months to get up to that amount of exercise.) And, Slentz notes, those walks can be tackled in 10- or 15-minute chunks in the course of the day. "Almost every drug has side effects," he notes. But with this approach, "you don't even get sweaty."
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