Ask The Doctors: January 2014
Q. Iíve been a runner most of my life, but I just read where long-distance running may damage the heart. Iím 57 and I have some family history of heart disease. Also, my last blood work showed some LDL cholesterol elevation. Iím not on a statin yet. I run between 20 and 30 miles a week. Should I ease off? I feel great and still enjoy running.
A. Iím glad you asked this question, since many people jog or run in the hopes of improving their cardiovascular health. Numerous clinical studies have shown the benefit of mild-to-moderate aerobic exercise (brisk walking, jogging, elliptical machine, swimming) performed from 30-60 minutes per session, three to seven days of the week. This sort of exercise generally leads to weight reduction, lower resting blood pressure, improved cholesterol values, and lower levels of circulating inflammatory biomarkers. It appears to lower the risk of heart attack and stroke, as well. While some individuals are comfortable with the above type of plan, others are interested in more intense types of exercise, engaging in long-distance running, or pushing their heart rates higher during shorter exercise durations. Anyone contemplating starting an exercise program should consult with their doctor about how to do this in a safe, gradual fashion, which doesnít put them at risk.
A study published this year in the journal Heart analyzed more than 50,000 adult Americans, their exercise patterns (about 14,000 were runners), and their cardiovascular health. The runners were more likely to live longer than the non-runners when the distance run per week was in the five to 20 mile range. No longevity benefit was obtained for running more than 20 miles per week. The reasons for this discrepancy are unknown. However, a possible explanation is that very intense and/or prolonged exercise could increase the level of oxidative stress, injuring the insides of coronary vessels, and leading to atherosclerosis (plaque formation) in spite of the personís high level of fitness. Very vigorous exercise leads to high oxygen demand by the heart muscle, greatly straining it and the coronaries which supply its blood. Such heavy strain can increase the risk of coronary artery plaque rupture and subsequent myocardial infarction. My recommendation to you, a 57-year-old in outstanding physical condition who can run 30 miles a week, would be to maintain your current sport, by all means. I would only suggest that you ďease offĒ to between 15 and 20 miles per week. In the long run, this will keep your heart healthier, and should increase the likelihood of you feeling great for longer.
Q. After my aortic valve replacement, I have monitored my blood pressure (BP) regularly. But when I do so my readings are inconsistent. For example, I had consecutive readings continually going down: 151/77, 145/70, 136/71, 135/69, and 133/61. Should I take the highest reading, the lowest reading, the median or average reading to represent the correct blood pressure?
I suspect that the downward trend in BP you recorded is due to recent activity, and not having rested long enough before starting to take measurements. First, you should bring the home machine to your doctorís office, to evaluate its accuracy side-by-side with the physicianís device. Once this is verified, make sure that you are always using the same arm, and removing all clothing from it. The cuff needs to be on bare skin. It is also very important that you are sitting quietly in a comfortable chair for at least five minutes before taking the BP. Obtain two measurements, with a one-minute interval between them, and record the average of these two readings. If the difference between the two systolic pressures (top numbers) or the two diastolic pressures (bottom numbers) is greater than 5mmHg, then additional measurements should be taken, recording the average BP.