Mean Arterial Pressure Formula: What Does it Mean?
The mean arterial pressure is the average blood pressure (BP) in the arteries throughout the cardiac cycle. This is a very important value as this number gives us more of an overall indication of the force exerted by blood against the arterial walls.
The average BP for a male is 120/80 mm Hg and 110/70 mm Hg for a female. The “120” represents systole, while the “80” represents diastole. The mean arterial pressure equivalent to this would be about 93.3 for men and about 83.3 for women.
The mean arterial pressure formula is 1/3 (SBP – DBP) + DBP at rest and 1/2 (SBP – DBP) + DBP during exercise.
Now that we know the mean arterial pressure formula, let’s break it down further to help you understand all of its components. In addition, I’ll also discuss some ways that you can decrease your mean arterial pressure to help you attain a healthier heart.
For starters, what is SBP and DBP?
SBP stands for systolic blood pressure. This is the pressure that the heart experiences during depolarization (contraction). DBP stands for diastolic blood pressure. This the pressure that the heart experiences during hyper-polarization (relaxation).
Systole occurs in both the atria and ventricles of the heart at different times. For example, when the heart receives blood in the right atrium it relaxes and fills with blood. This is called atrial diastole. After the right atrium is completely filled with blood it’s then ejected into the right ventricle. When this happens the atrial experiences systole (contraction).
During atrial systole, the right ventricle is in diastole as it fills up with blood via the tricuspid valve under the right atrium. When the right ventricle fills up with blood it experiences end-diastolic volume (EDV). Once this occurs the blood then enters the pulmonary semilunar valve into the pulmonary artery to the lungs.
However, before we get off track too much here, let’s go over why the mean arterial pressure formula has two different versions to it.
Why are there two distinct mean arterial pressure formula variations?
There are two mean arterial pressure formula variations to represent the arterial resistance experienced at rest and during exercise. The mean arterial pressure formula at rest is 1/3 (SBT – DBT) + DBT. You multiply by “1/3” due to the fact that diastole usually lasts longer than systole.
The mean arterial pressure formula during exercise is 1/2 (SBT – DBT) + DBT. During exercise, diastole lasts less time, so you multiply by “1/2” instead of “1/3”.
Aerobic exercise VS. Resistance exercise: How they effect mean arterial pressure
Not all exercise is created equal. With that being said, it’s very important to note that aerobic (or endurance) exercise affects mean arterial pressure much differently than resistance (or weight training) exercise does.
Aerobic exercise causes systolic blood pressure to increase while diastolic blood pressure stays at resting levels. With resistance exercise, systolic blood pressure increases and diastolic blood pressure may also increase as well, especially with greater muscle loads. So, you could expect mean arterial pressure to be higher during resistance exercise as opposed to aerobic exercise.
So, how do these two training methods affect the heart’s skeletal muscle tissue?
In short, endurance training produces an increase in the size of the left ventricle. Thus, allowing it to hold more blood. This is brought about by volume loading from endurance exercise causing an adaptation due to more blood volume returning to the left ventricle during exercise.
Resistance training produces an increase in the thickness of the left ventricle. Essentially, it has more mass to oppose resistance and is able to force more blood out. This is brought about by pressure loading from resistance exercise.
How to decrease mean arterial pressure
Decreasing your mean arterial pressure is as easy as decreasing your sodium intake and increasing exercise frequency. However, it is important to note that genetics plays a very significant role when it comes to your BP. Of course, if you are trying to decrease your BP you should first discuss a plan of action with your doctor to set yourself up for the best chance of success.
As far as your diet goes, try out seasoning your meals with salt-free spices. It probably won’t taste as good as salted seasonings, but you should try and make an active effort to make your health a priority. If not for you, than for your loved ones.
Weight resistance exercise is very helpful for decreasing BP levels, but aerobic exercise may be even better. Aerobic exercise can be anything from walking at the park for 10 mins a day to an intense tabata training session. Your initial fitness level will dictate just how intense you’ll be able to realistically workout.
Besides cleaning up your diet and exercising regularly, you may need to try out some medication depending on the status of your current health. Be that as it may, talking to your doctor before you make any rash decisions regarding this issue is best as you’ll have the greatest chance of achieving your goals of decreasing your mean arterial pressure.
Final thoughts on the mean arterial pressure formula…
Remember that there are two different mean arterial pressure formula variations you should know. The first one should be recorded at rest and is 1/3 (SBT – DBT) + DBT. The second calculation is 1/2 (SBT – DBT) + DBT and should be recorded during exercise.
You divide by “1/3” in the first mean arterial pressure formula because diastole usually lasts longer than systole at rest. In the second mean arterial pressure formula you divide by “1/2” because diastole lasts less time than systole during exercise.
Whether you’re a cardiac patient, a student, or simply a person who’s curious about their health, knowing the in’s and out’s of the mean arterial pressure formula may help you to better understand your body’s status quo.
Cleaning up your diet and starting an exercise program are huge factors for decreasing mean arterial pressure. More specifically, it’s the reduction of salt that will significantly help you to decrease your BP.
If you are sedentary then you need not workout to extremes thinking that more is better. Start off relatively slow and increase your exercise intensity and frequency when necessary. Remember to first talk to your doctor so you can be put on the right path to success early on.
Kraemer, Robert. “Cardiorespiratory Physiology.” Southeastern Louisiana University. 4 May 2017, PowerPoint file.