Martti Karvonen was born in Finland in 1918. He received a medical degree from the University of Helsinki in 1945 and a PhD degree from the University of Cambridge in 1950. His contribution to cardiovascular epidemiology began in the mid-1950s, when he observed that serum cholesterol levels were higher in men living in eastern Finland than those living in western Finland. He brought these observations to the attention of Ancel Keys, and the two collaborated on the first epidemiological studies of risk factors for coronary heart disease. This collaboration ultimately led to the inclusion of Finland in the hallmark 1958 Seven Countries study that established a relationship between lifestyle and the prevalence of atherosclerosis. Karvonen also developed a formula that can be used to determine a target heart rate for aerobic activity. Although the Karvonen formula can overestimate or underestimate the exercise intensity in certain patients, it provides general rule-of-thumb target heart rates, with light-intensity exercise being defined as activity using 30% to 40% of the heart rate reserve, moderate-intensity exercise using 40% to 60%, and vigorous-intensity activity using 60% to 90%. Ideally, physicians should provide patients with an exercise prescription that outlines the frequency, intensity, time (duration), and type of exercise. Exercise prescriptions should include both aerobic activity and resistance training. Patients with underlying cardiac conditions can benefit from a cardiac rehabilitation program with pre-participation cardiac assessment and development of a specialized exercise routine. [ABSTRACT FROM AUTHOR]