UF study finds resistance exercise protects against harmful free radicals

For years, aerobic exercise has been touted as a key to preventing heart disease, but now it turns out that buffing your biceps and pumping your pecs also may be heart healthy.

A new University of Florida study has found that weightlifting protects the body against damage from free radicals—those naturally occurring, highly reactive molecules that lately have been linked not only to cardiac problems, but also to aging-related disorders, stroke and even cancer.

“Resistance exercise is healthy because it can do things that aerobic exercise can’t in terms of improving strength to carry groceries or to help you walk up a flight of stairs. Now we’ve also shown that weight training, even at low intensities, provides protection from free radicals. That’s a benefit only before found in high-intensity aerobic exercise,” said Kevin Vincent, who presented his findings Wednesday May 31 at the annual meeting of the American College of Sports Medicine in Indianapolis.

Vincent, a UF medical student, holds a doctorate in exercise physiology from UF’s College of Health and Human Performance. In the first study of its kind, UF scientists found that healthy elderly people who performed a series of weight-resistance exercises three times per week for six months had lower blood level evidence of free radical damage than a group who didn’t exercise. Weightlifting did not decrease the levels; rather it appeared to prevent the usual aging-related increase observed in the control group by either reducing the formation of free radicals or providing better antioxidant protection against them.

“The resistance exercise likely improved the body’s defense mechanism so you didn’t find that normal physiological increase,” Vincent said.

Because they have been implicated in so many diseases, free radicals have become a hot topic of research in recent years. They also have become buzzwords in advertisements for antioxidants such as vitamins C and E, acclaimed for their ability to fight the molecules that damage cells and tissues.

Normal byproducts of routine metabolism, free radicals result when molecules split and leave highly reactive electrons. In their unstable form, they maraud through the body in search of another electron to pair up with, attacking and destroying parts of cells in the process. The body possesses protective antioxidant mechanisms to defend against the molecules, but those defenses break down with age.

In a six-month study, the scientists tracked for six months 62 healthy adults ages 60 to 85. During that time, one group performed high-intensity weight-resistance exercise while another performed low-intensity weight training three times a week. They performed 12 different exercises targeting all the major muscles of the body. A third set of research participants served as a control group and did no exercise.

At the end of the six months, the levels of lipid peroxidation, evidence of free radical damage, increased significantly in the nontraining group but stayed the same in the weightlifters during a test in which all the participants were asked to walk on a treadmill until they could walk no longer. The levels increased 13 percent in the group who did not exercise, while they increased just 2 percent in the high-intensity exercisers and declined 2 percent in the low-intensity group. Lipid peroxidation was measured in the blood by two specific biochemical markers.

In addition to the defense against free radicals, the study showed weight-resistance exercise provided a variety of other advantages, including improved aerobic and cardiovascular fitness, and boosts in muscular strength and endurance. The high-intensity group also showed increased bone density and decreased blood concentrations of homocysteine, a risk factor for heart disease.

“Resistance exercise has traditionally been thought of as only for people who want to build large muscles or look better at the beach. Typically, aerobic exercise is viewed as being beneficial for health. Now we, and other researchers, have recently begun to show that the same is true for resistance exercise,” Vincent said.

The results showed similar benefits in the low- and high-intensity training groups.

“We think this will open up the options for prescribing exercise to seniors and other populations allowing them to use lighter loads that are less likely to cause injury but can still provide the same benefits,” he said.

Vincent collaborated on the study with UF scientists Randy W. Braith and Dr. David T. Lowenthal, both affiliated with the universitywide Institute on Aging; UF doctoral student Shannon Lennon and former UF researcher Heather Vincent who is now an assistant professor at Stetson University.

Calling the UF results provocative and important, Barry Franklin, president of the American College of Sports Medicine, said, “These findings suggest that resistance training in older adults may confer additional metabolic benefits, namely reduced serum lipid peroxidation, which may reduce the potential for chronic disease and/or attenuate selected declines in function commonly attributed to the aging process.”