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Strength Training Improves Aerobic Power in Seniors

GAINESVILLE, FL -- March 29, 2002 -- For healthy older men and women, strength training not only firms muscles, but also significantly improves physical endurance and aerobic power, which can help prevent or delay a number of diseases including heart disease, according to a University of Florida study.

Most exercise regimens focus on aerobic or endurance exercise-such as walking, jogging and riding a bicycle-to boost cardiovascular conditioning. The UF researchers say their findings are the first to demonstrate improved aerobic capacity in healthy elderly adults following both low- and high-resistance exercise training programs. The study is published in the March issue of The Archives of Internal Medicine.

"Strength training is not typically viewed as a means for improving cardiovascular and respiratory performance. We've crossed over and have shown that muscle resistance exercise may be another valid means of increasing cardio-respiratory endurance in older adults," said Kevin Vincent, the study's principal investigator. Vincent, who designed and led the study while earning his doctorate in exercise physiology at UF, conducted the study with researchers from UF's colleges of Medicine, and Health and Human Performance. He also is a third-year medical student at UF's College of Medicine.

"Reduced cardiovascular and respiratory fitness is associated with increased risk of cardiovascular disease, stroke, hypertension and death," Vincent said. "Strength training isn't just for helping you look good at the beach. These findings indicate that healthy older adults should incorporate resistance weight training into a comprehensive exercise regimen to increase muscular strength, cardio-respiratory endurance and physical function."

Diseases of the heart are the No. 1 killer in the United States, and stroke is the No. 3 killer, according to the American Heart Association.

A surprising result of the UF study of 62 men and women between the ages of 60 and 83 was that the intensity of exercise had little effect on the rate of aerobic capacity improvement. Twenty-four participants in a low-intensity training group increased their peak oxygen consumption by an average of nearly 24 percent. A second group of 22 volunteers exercising at higher intensity-pumping heavier iron-improved by about 20 percent. A control group of 16 non-exercisers performed only the pre-study and post-study exercises for comparison.

Study participants exercised three times a week for six months. During each session, they performed one set each of 12 exercises on MedX resistance machines, such as abdominal crunch, leg press, seated row, chest press and biceps curl.

Time to exhaustion-the time it took participants to reach voluntary maximum exertion on an incremental treadmill test-increased by more than 26 percent in the low-intensity training group, and by about 23 percent in the high-intensity group. The control group of non-exercisers increased their exhaustion time by only about 6 percent.

"The message here is that you can participate in a low-intensity strength-training program, with more repetitions but less weight, and still receive beneficial aerobic improvement," Vincent said.

Researchers say it's unclear exactly how resistance exercise increases aerobic power. They speculate that the aerobic improvement may trigger metabolic or enzymatic activities that improve the body's use of oxygen needed for energy.

"Another possibility is that increased leg strength may allow aerobic exercise training bouts to be performed at a greater intensity or for a longer duration, which also leads to improvements in aerobic capacity," Vincent said.

In studies of younger adults done elsewhere, resistance exercise hasn't produced the same improvement in aerobic power. Vincent said one explanation may be that weight training doesn't generate enough oxygen consumption for their higher aerobic capabilities. Another reason may be that younger adults already possess normal leg strength, so there's a smaller margin for improvement.

"Aerobic response to resistance exercise may be influenced by age and conditioning," Vincent said. "For people over 60, the best choice is to pursue both aerobic and strength training for maximum benefits."

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