9.7: Guest Lecturer

Guest Lecturer : Peter D. Wood, DSc, PhD

A Runner’s High—HDL

We runners are a dedicated bunch. In the early 1960s, however, we weren’t a very big bunch. One evening after work, I was running around Lake Merritt in Oakland, California, in my running shorts. It was dark, cold, and raining. A police car pulled alongside, and the officer asked suspiciously what I was doing running around in my underwear. After I explained myself, there was a long pause before he said, “Well, you have to admit, this is not normal!”

Running is more normal now, but not normal enough. Physical activity is important to one’s health, and it has been my good fortune to combine this message and my love of running with my scientific endeavors.

One of my earliest studies on the effects of exercise, published in 1965, was on how certain fatty acids in the blood differ in how they are taken up by working muscles during vigorous exercise (e.g., running a mile in about 5 minutes).¹ In going on to study lipoproteins in blood, I noted that I had a lot of a particular kind—HDL (High-Density Lipoprotein). Indeed, runners have higher HDL.

In comparing a group of long-distance runners (43 women, 41 men), matched for age and sex with a larger control group, my colleagues and I found that the runners not only had higher HDL-cholesterol, but lower LDL-cholesterol.² Low HDL-cholesterol raises the risk of cardiovascular disease, as does high LDL-cholesterol.

HDL-cholesterol can also be raised by losing excess weight. In one study, we randomly divided 131 overweight sedentary men into 3 groups. A diet-only group was put on a low-calorie diet with no change in physical activity; an exercise-only group was put on an exercise program (mainly running) without lowering calorie intake; and the third group was the control group. At the end of the year-long study, both the diet-only and exercise-only groups lost weight and increased their HDL-cholesterol.³

The diet-only group lost more weight (-17 lbs) than the exercise-only group (-10 lbs), but a greater portion of the weight loss was from lean body mass in the diet-only group (27% vs. 15%). In other words, the men lost weight and raised HDL-cholesterol by diet alone or exercise alone, but exercise helped prevent the loss of lean body mass. A good combination, of course, is to eat less and exercise more, because the calorie-restriction and increased exercise can be more moderate, making it easier to stick to the weight-loss plan.

The risk of having low HDL-cholesterol is greater in those who also have a high LDL-cholesterol and are older. We took 180 postmenopausal women (age 45-64) and 197 men (age 30-64) who had this combination of risk factors and randomly assigned them to four groups: aerobic exercise, diet moderately low in fat and cholesterol, exercise plus diet, and control. At the end of the year-long study, all groups had lower LDL-cholesterol, but only the diet+exercise group had a big enough drop to reach statistical significance. For HDL-cholesterol, the exercise group had the biggest rise, but the intra-group variations were so large that there were no statistically significant differences in HDL-cholesterol between the groups.⁴

The studies are complex, but they all point to the simple message that physical activity is important to one’s health. Exercise not only lowers the risk of obesity, heart disease, and some cancers, it also adds to the quality of life. I run for the joy of running; the higher HDL and other health benefits are but a bonus.

Studies Cited

1. Wood P, Schlierf G, Kinsell L. 1965. Plasma free oleic and palmitic acid levels during vigorous exercise. Metabolism 14:1095-1100.
2. Wood PD, Haskell WL, Stern MP, Lewis S, Perry C. 1977. Plasma lipoprotein distributions in male and female runners. Annals of the New York Academy of Sciences 301:748-763.
3. Wood PD, Stefanick ML, Dreon DM, Frey-Hewitt B, Garay SC et al. 1988. Changes in plasma lipids and lipoproteins in overweight men during weight loss through dieting as compared with exercise. New England Journal of Medicine 319:1173-1179.
4. Stefanick ML, Mackey S, Sheehan M, Ellsworth N, Haskell WL, Wood PD. 1998 Effects of diet and exercise in men and postmenopausal women with low levels of HDL cholesterol and high levels of LDL cholesterol. New Eng. J. of Med. 339:12-20.

^{Dr. Wood did research in England and Australia before coming to California. He was part of the research faculty in the Stanford Heart Disease Prevention Program for more than 20 years. In addition to his extensive scientific work, he was on the Science Advisory Board of Runner’s World magazine for more than 10 years, and was chairman of the Science Advisory Board of Marathon & Beyond magazine. He ran more than 100 marathons, placed 35th in the 1968 Boston Marathon (2:49:40), ran in the first 5-boroughs New York Marathon in 1976 at age 47 (3:05:52), and still ran marathons at age 78. He touted “HighHDL” on his license plate and in his email address.}