BIRMINGHAM, ALABAMA. A group of American and South Korean researchers sheds new light on the long debated question concerning the most important factor in determining the benefits of exercise for cardiac patients. Is it intensity, frequency or duration? Their study involved 185 middle-aged men with diagnosed heart disease. They were randomized into two groups – the high-intensity group and the low-intensity group. The high-intensity group exercised three non- consecutive days each week at a target heart rate of 85 per cent of maximum oxygen uptake while the low-intensity group exercised at a target heart rate of 50 per cent. All exercise sessions consisted of 30 minutes of walking or jogging, 15 minutes of stationary cycling, with 5- to 15-minute warm-up and cool-down sessions. The experiment lasted for 12 months and all the participants had a thorough clinical evaluation at baseline, after six months, and again after 12 months. There was little overall effect on cholesterol parameters in the two groups and the high-intensity group did not derive any greater benefits from exercise than did the low-intensity group. The researchers did note, however, that the more exercise sessions a participant attended the greater the benefits. Frequent attendees showed a significant increase in their blood levels of "good" (HDL) cholesterol and a marked improvement in the all-important HDL:LDL ("bad") cholesterol and HDL:total cholesterol ratios. The researchers conclude that exercise frequency may be more important than intensity for favourably influencing cholesterol levels.
Kim, Jang-Rak, et al. Effect of exercise intensity and frequency on lipid levels in men with coronary heart disease: Training Level Comparison Trial. American Journal of Cardiology, Vol. 87, April 15, 2001, pp. 942-46