Cardiologist Dr. Paul D. Thompson, MD, draws on his own research with distance runners to explain why exercise lowers LDL cholesterol only slightly, why it has a much larger effect on triglycerides, and why he still trains almost daily.
Exercise and Cholesterol: What Studies of Runners Show About LDL and Triglycerides
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- Preventing high cholesterol
- Runners who stopped running
- Exercise and triglycerides
- Triglycerides after a marathon
- Training for old age
- Full Transcript
Preventing high cholesterol
Preventing high cholesterol, says cardiologist Dr. Paul D. Thompson, MD, is a matter of picking the right parents. Asked by Dr. Anton Titov, MD, whether exercise helps, his short answer is: only a very little bit.
He had NIH funding for 11 years to study how distance runners metabolize cholesterol. Athletes, he says, have very high levels of HDL, the "good" cholesterol, but their LDL, which he calls the "ugly" cholesterol, is only a little bit lower.
Runners who stopped running
A study from the 1990s is his main example. He took 12 friends who, like him, were running 10 miles a day, fed everybody all their meals from a metabolic kitchen, and paid the runners 10 dollars a day to stop running. Within two days of stopping, their LDL cholesterol went up about 8%.
Their plasma volume, the amount of fluid in the bloodstream, also went down, by 6 to 8%. His group therefore thinks the lower LDL in endurance athletes is due to dilution. He compares exercise training, which expands the fluid in the bloodstream, to filling up a car radiator before a long drive on a hot day.
Exercise and triglycerides
Triglycerides are where exercise has a big effect, he says, along with the "good" HDL level. He describes a study from 1964 in men with triglyceride levels of 500. After a three-mile run, levels were about 350 the next day, and after further runs they fell to around 280, going down day by day.
His explanation is that exercise burns calories, including fat in and around the muscle. The body wants to replace that fat, so it takes triglycerides, which he describes as just fat, out of the blood.
Triglycerides after a marathon
A second study by his group followed 12 men, including Dr. Thompson and friends, who ran the Newport Marathon, a race of 26.2 miles, or 42 kilometers. Triglycerides were 90 the day before and on the morning of the Sunday race, 33 on Monday morning, 60 on Tuesday morning, and back to 90 on Wednesday morning.
Training for old age
Exercise alone is not the answer to high cholesterol levels, in Dr. Thompson's view, although it helps a little. He sees it as more useful for keeping fit and in shape, and he tells people to train for old age, because muscle mass is lost with aging.
At 79, he says, he hardly ever misses a day at the gym, and he was there at 7 o'clock on the morning of the interview to preserve what muscle mass he can. He calls exercise a very important part of health for many reasons, but not a strong tool for lowering cholesterol.
Full Transcript
Dr. Anton Titov, MD: How can I prevent high cholesterol in the first place, and does exercise help?
Dr. Paul D. Thompson, MD: So preventing high cholesterol level is picking the right parents. Now, does exercise help? Only a very little bit.
Dr. Paul D. Thompson, MD: So I had funding from the NIH for 11 years to study how distance runners metabolize cholesterol. Athletes have very high levels of the good cholesterol, HDL cholesterol. Their ugly cholesterol level is only a little bit lower.
Dr. Paul D. Thompson, MD: It is not a lot lower. So I did a study way back in the 1990s where I took 12 of my friends who were running, and myself, who were running 10 miles a day. We fed everybody all their meals.
Dr. Paul D. Thompson, MD: I had a metabolic kitchen where we could feed them. And we paid the runners 10 bucks a day to stop running their 10 miles a day. And a very interesting thing happened.
Dr. Paul D. Thompson, MD: Within two days, so you stop, day one, day two. Within two days of stopping running, their ugly cholesterol level, their LDL cholesterol level, went up about 8%. It went up 8%.
Dr. Paul D. Thompson, MD: But here is the interesting thing. Their plasma volume, how much fluid they had in their bloodstream, went down 6 to 8%. So we think that the lower ugly cholesterol level in endurance athletes is due to dilution.
Dr. Paul D. Thompson, MD: When you exercise train, you expand the amount of fluid in your body. Your body does that naturally. It is almost like filling up the radiator to drive the car on a hot day.
Dr. Paul D. Thompson, MD: Now, we never worry about the radiator anymore, but when I was a kid, the radiator could overheat and you could get stuck. So you filled up the radiator before you went for a long drive. The body, when you exercise, expands the amount of fluid in the bloodstream.
Dr. Paul D. Thompson, MD: We think that that expansion of fluid lowers the ugly cholesterol level. Now I will tell you where exercise has a big effect. Exercise has a big effect on not the ugly level.
Dr. Paul D. Thompson, MD: It does have a big effect on the good level, but it has a big effect as well on the bad level, the triglyceride level. There is a study done way back in 1964 where they took a bunch of men whose triglyceride levels were high. They were 500.
Dr. Paul D. Thompson, MD: They had them run three miles. The next day, their triglyceride levels were about 350. They had them run several miles.
Dr. Paul D. Thompson, MD: The next day, their triglyceride levels were down to 280 or something. They had them run the three miles. They were down.
Dr. Paul D. Thompson, MD: So day by day. Now, how does that happen? When you exercise, you burn calories.
Dr. Paul D. Thompson, MD: And some of those calories that you burn are fat from the muscle and from around the muscle. And so the body wants to replace the fat that was burned around and in the muscle. So it takes triglycerides out of the blood.
Dr. Paul D. Thompson, MD: Triglycerides are just fat. They are just fat floating around in those bad particle levels. So we did another study where we took 12 men, myself and a bunch of my friends, who were running the Newport Marathon.
Dr. Paul D. Thompson, MD: Now, a marathon is 26.2 miles, or 42 kilometers. The day before the race, and on the morning of the race, the triglyceride level was 90. The morning after the race, the race was on Sunday, so Monday morning, the triglyceride levels were 33.
Dr. Paul D. Thompson, MD: On Tuesday morning, they were 60, and on Wednesday morning, they were back to 90. So when you exercise, you deplete triglycerides, you use them up for energy, and you have to replace them, so the body takes triglycerides out of the blood to replace what is lost. But otherwise, exercise is not the way to cure cholesterol levels.
Dr. Paul D. Thompson, MD: It helps. It is good to exercise. Exercise, quite frankly, is better for just keeping yourself fit and in shape.
Dr. Paul D. Thompson, MD: I tell people that you want to train for old age. You want to train to live a long period of time. One of the things that happens when you get older is you lose muscle mass.
Dr. Paul D. Thompson, MD: I am 79. I know you lose muscle mass. I was at the gym this morning at 7 o'clock, because I hardly ever miss a day going to the gym to get some exercise to preserve what muscle mass I can.
Dr. Paul D. Thompson, MD: But exercise is a very important part of health for many reasons, but for lowering cholesterol level, it helps a little bit, but not so much.