Lifting weights for less than an hour a week may reduce your risk for a heart attack or stroke by 40 to 70 percent, according to a new Iowa State University study. Spending more than an hour in the weight room did not yield any additional benefit, the researchers found.

"People may think they need to spend a lot of time lifting weights, but just two sets of bench presses that take less than 5 minutes could be effective," said DC (Duck-chul) Lee, associate professor of kinesiology.

The results -- some of the first to look at resistance exercise and cardiovascular disease -- show benefits of strength training are independent of running, walking or other aerobic activity. In other words, you do not have to meet the recommended guidelines for aerobic physical activity to lower your risk; weight training alone is enough. The study is published in Medicine and Science in Sports and Exercise.

Lee and his colleagues analyzed data of nearly 13,000 adults in the Aerobics Center Longitudinal Study. They measured three health outcomes: cardiovascular events such as heart attack and stroke that did not result in death, all cardiovascular events including death and any type of death. Lee says resistance exercise reduced the risk for all three.

"The results are encouraging, but will people make weightlifting part of their lifestyle? Will they do it and stick with it? That's the million-dollar question," Lee said.

Barriers to resistance training

The researchers recognize that unlike aerobic activity, resistance exercise is not as easy to incorporate into our daily routine. Lee says people can move more by walking or biking to the office or taking the steps, but there are few natural activities associated with lifting. And while people may have a treadmill or stationary bike at home, they likely do not have access to a variety of weight machines.

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For these reasons, Lee says a gym membership may be beneficial. Not only does it offer more options for resistance exercise, but in a previous study Lee found people with a gym membership exercised more. While this latest study looked specifically at use of free weights and weight machines, Lee says people will still benefit from other resistance exercises or any muscle-strengthening activities.

"Lifting any weight that increases resistance on your muscles is the key," Lee said. "My muscle doesn't know the difference if I'm digging in the yard, carrying heavy shopping bags or lifting a dumbbell."

Other benefits of strength training

Much of the research on strength training has focused on bone health, physical function and quality of life in older adults. When it comes to reducing the risk for cardiovascular disease, most people think of running or other cardio activity. Lee says weight lifting is just as good for your heart, and there are other benefits.

Using the same dataset, Lee and his colleagues looked at the relationship between resistance exercise and diabetes as well as hypercholesterolemia, or high cholesterol. The two studies, published in Mayo Clinic Proceedings, found resistance exercise lowered the risk for both.

Less than an hour of weekly resistance exercise (compared with no resistance exercise) was associated with a 29 percent lower risk of developing metabolic syndrome, which increases risk of heart disease, stroke and diabetes. The risk of hypercholesterolemia was 32 percent lower. The results for both studies also were independent of aerobic exercise.

"Muscle is the power plant to burn calories. Building muscle helps move your joints and bones, but also there are metabolic benefits. I don't think this is well appreciated," Lee said. "If you build muscle, even if you're not aerobically active, you burn more energy because you have more muscle. This also helps prevent obesity and provide long-term benefits on various health outcomes."