Three cheers for the artful joggers, for they may preserve their hearts! This is the message of the author, a Canadian doctor who is a specialist in the physical rehabilitation of heart attack patients. Time-honored wisdom was that the victim must take it easy, risk no stress or strain. On the contrary, it is now known that a carefully graded program of exercise can be heart-strengthening. The idea is that a measured amount of stress--beginning, say, with walking a mile in twelve minutes every day for five days--will in time lower heart rate, pump more blood at each beat, lower blood pressure, get more oxygen to muscles, reduce clotting time, and decrease blood fats. Kavanaugh is very good at explaining why these physiological effects occur, which kind of heart patient can benefit, how an individual's exercise level is determined, and when he can step up to a higher level. He also includes a discussion of the major risk factors implicated in heart disease. Formal ""endurance exercise"" programs are relatively new so there are not many statistics, but the few cited do suggest that the incidence of second attacks or of mortality is significantly lower for the exercisers. A very hopeful book, which incidentally applies to normal people as well; as Kavanaugh notes, long-distance runners almost never have heart disease.