In the November 5 issue of the New England Journal of Medicine, researchers from Duke University report that moderate exercise produces favorable changes in lipid profiles - even if it is not enough exercise to lead to weight loss.
The researchers described the results from their study, Studies of Targeted Risk Reduction Interventions through Defined Exercise (STRRIDE), in which 111 overweight, sedentary men and women were randomized to one of four groups. The first group remained sedentary. The other three groups assigned to different levels of exercise: a) high amount, high intensity (the equivalent of jogging 20 miles per week), b) high amount, moderate intensity (equivalent to jogging 12 miles per week), or c) low amount, moderate intensity (equivalent to walking 12 miles per week). Lipid composition was measured at baseline, and again six months after being assigned to groups.
All three exercise groups had improvements in their plasma lipid composition when compared to the control group, and these improvements were not related to weight loss (which, in general, did not occur to any great extent in these three groups).
The improvement in lipids seen in STRRIDE was not so much in LDL or HDL cholesterol levels (though improvement here was seen in the high amount, high intensity group, and a decrease in triglycerides occurred in all three exercise groups), but instead in the size of the LDL particles. While LDL size is not (yet) a part of the standard lipid profile measures in patients, it is known that small, compact LDL particles are much worse than large, "fluffy" LDL particles. In this study, patients in all three exercise groups had significant increases in the size, and a decrease in the number, of their LDL particles.
Take Home Message
Despite the recent report from the Institute of Medicine suggesting that we all need to exercise an hour a day, STRRIDE offers yet another important indication that much more moderate exercise levels can yield significant cardiovascular benefits.The bottom line is that being sedentary is hazardous to your health. If you can afford to dedicate an hour a day to vigorous exercise, swell. But don't throw in the towel just because you can't meet certain standards advanced by eggheads in academia. While the more exercise you do the better (at least, to the point that it doesn't lead to being fired or to divorce), any amount of exercise is good. So do what you can, and be confident that you are helping yourself.
