Ask the doctor: Best way to work out
Q. What is better for my heart—a fast run on the treadmill for 10 minutes or 30 minutes of light cycling on a machine?
A. The benefit of exercise on heart health depends on the dose; in other words, the more the better. So, my answer to your question is "Why not do both?" Exercise of virtually any kind prevents heart attacks, strokes, high blood pressure, and diabetes.
Most studies indicate this benefit begins at low levels of exercise, and increases with higher amounts of exercise. A good general goal is 150 minutes of moderate exercise per week. Moderate exercise is the equivalent of a brisk walk or speedy yard work—enough to increase your breathing rate and cause you to break a sweat.