The amount of exercise is more important than how hard one exercise in terms of heart health. Researchers from the Duke University Medical Center in Durham, North Carolina found that people who walk briskly for 12 miles per week or for about 125 to 200 minutes per week can significantly improve their aerobic fitness and lower their risk of developing a heart disease. Anything beyond walking briskly for 12 miles per week, whether it is increasing the intensity or the amount of miles, has additional benefits. So there is a separate and combined effect. People who walked 12-miles-per-week improved their fitness without losing any weight. Even without losing weight, people can gain significant benefits by exercising. These include improving the fitness level, decreasing fat and increasing muscle and improving the lipid panel. So one should not stop exercising. There is a clear link between heart health and fitness. However, less is known on how the amount and intensity of exercise is related to the increase in fitness for individuals at risk for heart disease. To better understand the effects of different amounts of exercise on aerobic fitness, researchers randomly assigned 133 overweight sedentary men and women showing signs of rising cholesterol levels to 7 to 9 months of no exercise; low amount/moderate intensity exercise (the 12-miles per week walkers); low amount/vigorous intensity (12 miles of jogging per week); or high amount/vigorous intensity (20 miles of jogging per week). The participants did not alter their diet during the study. After completing their exercise assignment, all had improvements in peak oxygen consumption and time to exhaustion - two established markers of fitness - compared with levels at the beginning of the study. However, the vigorous intensity exercisers did not get any fitter than the moderate intensity exercisers. The moderate intensity group only exercised to 40 or 50 percent of their maximum. That's walking briskly up a hill or walking fast – one can walk around the neighborhood after dinner and get that in. One does not have to jog, climb the stairmaster or elliptical trainer and kill them. However, increasing the amount of exercise from 12 to 20 miles per week, at the same intensity provides even more cardiovascular benefits. Therefore it is appropriate to recommend mild exercise to improve fitness and reduce cardiovascular risk, yet encourage higher intensities and amounts for additional benefits.
Chest,
October 2005