DURHAM, N.C. – Scientists examining the relationship between the intensity and length of a workout and the duration of its benefits have made a surprising discovery: More isn't necessarily better, and none may be worse than we ever imagined.
"On the surface, it seems to make sense that the harder we exercise, the better off we'll be, and by some measures that's true," says lead author Cris Slentz, Ph.D, an exercise physiologist at Duke University Medical Center. "But our studies show that a modest amount of moderately intense exercise is the best way to significantly lower the level of a key blood marker linked to higher risk of heart disease and diabetes. More intense exercise doesn't seem to do that."
What may be even more remarkable, he says, is that some of the benefits derived from a modest exercise regimen appear to last much longer than those gained from a more rigorous program.
Triglyceride lowering benefits of exercise were longer lasting for those who only exercised moderately.
The researchers found that for the most part, no amount of exercise significantly changed LDL levels. HDL levels, however, tended to improve with the length and intensity of the workout, and that the benefit was sustained over time.
But perhaps the most interesting finding was that a modest, low-intensity workout – walking just 30 minutes per day, for example, dramatically lowered triglyceride levels. Triglycerides are the particles that carry fat around in the body, and they're also a good indicator of insulin resistance, a marker for diabetes. Lowering triglyceride levels lowers risk of heart disease and diabetes.
"A proper exercise program appears to be able to lower a person's insulin resistance in just a matter of days," says Kraus. "We were also amazed to see that the lower triglyceride levels stayed low even two weeks after the workouts ended." Longer, more intense workouts didn't have nearly the same impact, they say.
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