There is good news for people who think they do not have time to exercise. A group of researchers from a university in Canada recently published a study that says short bursts (爆发) of high-intensity exercise are good for you. In fact, this kind of exercise is just as good as spending up to an hour riding a bike or running steadily. The research team followed 27 men who were not very active for 12 weeks. They divided the men into three groups. One group did short, intense exercise on a bicycle three times a week. Another group rode a bicycle for about 50 minutes, three times a week. A third group did nothing.