When you visit your physician for a physical, they probably draw some blood for some routine studies, one of which is a lipid profile. A basic lipid profile includes the following:
· Total cholesterol – a measure of the total number of particles, also known as lipoprotein particles, which carry cholesterol in your blood
· Low-density cholesterol (LDL-C) – the amount of cholesterol carried on LDL particles. We think of LDL-cholesterol as an unhealthy form of cholesterol since studies correlate it with a higher risk of cardiovascular disease.
· High-density cholesterol (HDL-C) – sometimes called “good cholesterol” since it removes cholesterol deposits from the inner walls of arteries as it circulates. A higher HDL-cholesterol is associated with a lower risk of cardiovascular disease based on some studies.
· Triglycerides – a measure of lipoprotein particles carrying triglycerides, a form of fat carried in the bloodstream. A higher triglyceride level is linked with a greater risk of cardiovascular disease.
Some laboratories also calculate two other parameters:
· Very low-density lipoprotein (VLDL)
· Cholesterol to HDL ratio
These values also serve as markers of cardiovascular risk. Using these values, health care professionals can give you a better idea of your risk of developing atherosclerotic heart disease. However, lipid values don’t tell the full story. Other factors impact your risk of heart disease, including blood pressure, blood sugar, body weight, lifestyle habits, and family history.
Up to half of all people who have a heart attack have a normal total cholesterol level, so lipids are only one factor that determines your risk of cardiovascular disease. Preliminarily, it looks like elements such as the size of the lipoprotein particle carriers may be a factor and this isn’t reflected in a routine lipid panel. However, more advanced lipid testing is available that can determine particle size.
The lowest risk of cardiovascular disease from a lipid standpoint corresponds to LDL-cholesterol below 130 mg/dL, if you’re at low risk of cardiovascular disease, and below 100 mg/dL if you’re at higher risk based on family history and other factors. It’s also optimal to have HDL-cholesterol above a certain level (greater than 40 mg/dL). A normal triglyceride level is less than 150 mg/dL.
If your lipid values are out of range and your physician recommends getting them back into line, lifestyle changes can have some impact, including diet and exercise. You might wonder how much of an impact exercise has on lipids?
Can You Change Your Lipid Profile with Exercise?
Exercise, in general, has a favorable effect on blood lipids, particularly HDL-cholesterol. Remember, HDL-cholesterol is the “good guy” with regard to keeping your blood vessels free of plaque. It circulates in the bloodstream and takes up cholesterol that could lodge in the walls of your arteries and eventually rupture. After greedily grabbing as much circulating cholesterol as it can, HDL carries it back to the liver where it can be broken down. So, HDL-cholesterol, based on current knowledge, has a “clean-up” function. It “sweeps up” and carry the so-called “bad” cholesterol, LDL-cholesterol, back to the liver.
Now, what about exercise? Aerobic exercise has a modest effect on HDL-cholesterol. In a meta-analysis of 25 randomized, controlled studies, exercise raised HDL by an average of 2.53 mg/dL. To get the benefits, you need to work out at a high enough intensity, 65% of V02 max or higher. Low-intensity exercise doesn’t have a significant impact on HDL-cholesterol, although it may lower the risk of cardiovascular disease by relieving stress.
What about LDL-cholesterol, the so-called bad form of cholesterol? The benefits of exercise on LDL aren’t as clear-cut. Some studies show aerobic exercise modestly lowers LDL-cholesterol while others show little or no benefit. The benefits are greater when exercise leads to weight loss. However, higher intensity exercise may offer LDL lowering benefits for people who are obese. In one study, healthy but obese participants that did high-intensity training 20 minutes per day three days a week enjoyed a significant reduction in LDL-cholesterol.
How about triglycerides? People who have abnormally high triglycerides see the biggest reduction in triglycerides while those with only modestly elevated levels experience only small or non-significant reductions in response to aerobic exercise.
Exercise Intensity Matters
To get the modest benefits that exercise has on lipids, ramp up the intensity. Five-minute exercise sessions, no matter how intense, probably won’t impact your lipid level while a 20 to 40 minute relatively intense training session may. Some studies suggest that the benefits are correlated with the total amount of energy expended. So, more intense sessions and longer duration exercise should offer more benefits.
If you don’t work out at a high intensity, you may still get improvements in HDL-cholesterol if you exercise at a moderate pace for a longer period of time or work out more frequently. In one study, women who ran more than 37 miles per week experienced a greater increase in HDL-cholesterol than those who ran less than 30 miles weekly. So, if you do less intense workouts, you likely need to work out longer to get HDL-lowering benefits.
Even if you don’t notice drastic changes in your lipid level from exercise, exercise has other heart health benefits including:
Lowering blood pressure
· Easing stress
· Reducing inflammation
· Lowering body weight
· Increasing insulin sensitivity
So, you’re benefiting your heart no matter what your lipid report tells you.
The Bottom Line
Aerobic exercise may modestly improve your lipid profile, especially if you have a low HDL-cholesterol. To see benefits, aim for a higher intensity or a longer duration if you’re doing moderate-intensity workouts. Also, don’t forget that exercise lowers your risk of cardiovascular disease independent of its impact on lipids through the other mechanisms mentioned. So, keep exercising and know that you’re doing something good for the most important muscle in your body, your heart!
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