Is Weight Lifting Bad for Your Heart?
Should you worry about your blood pressure if you are lifting heavy weights? Get-Fit Guy explains the connection between weight lifting and your heart.
Quick, hold your breath!
Now, try to make a giant “oomph” sound without actually letting go your breath. You’ll feel lots of pressure build up inside you as you do this. The Valsalva maneuver is the term given to this action of creating lots of internal pressure by trying to breathe out against a closed epiglottis (the fancy anatomical word for the flap that opens and closes your esophagus). You may also be familiar with the Valsalva maneuver as something that you do when you pinch your nose shut and try to equalize pressure when you diving deep underwater, or something you do on a plane to try to equalize pressure in your ears.
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But often, even if you do it by accident, you perform the Valsalva maneuver you're your lifting weights. Based on the fact that this Valsalva maneuver can increase internal pressure, there is a prevailing belief the same type of “oomph” sound you make during weight lifting increases your blood pressure, and may actually make you more prone to a heart attack if you have heart problems.
But is it a misconception that weight lifting raises blood pressure, or should you really steer clear of the weights if you have heart issues or high blood pressure? You’re about to find out.
What Is Blood Pressure?
Let’s start with a quick introduction to what blood pressure actually is. The Quick and Dirty Tips House Call Doctor also has a great episode about blood pressure. Blood pressure is a measure of the pressure exerted by circulating blood on the walls of blood vessels as blood is pumped through your body.
The pump in your body is, of course, the heart. The heart is a hollow muscle that squeezes blood out to the body. There are two chambers, called ventricles, that do the pumping:
Right ventricle: The right ventricle pumps blood to the lungs so it can get oxygen.
Left ventricle: The larger left ventricle pumps blood to the rest of the body.
There are two parts of the heart’s pumping cycle: the part where it relaxes and fills up with blood, called diastole, and the part where it squeezes blood out to the body, called systole.
The two parts of the heart’s pumping cycle are important because they coincide with the two important blood pressure numbers.
Systolic pressure: Systolic pressure happens when the heart squeezes
Diastolic pressure: Diastolic pressure is the lowest pressure in the cycle, which happens when the heart relaxes.
So when a blood pressure cuff is inflated, the highest pressure at which the person listening with the stethoscope hears a “thunk” is the systolic pressure. The lowest pressure in the cycle, or the diastolic pressure, is signified by when the “thunk” sound goes away.
Blood pressure is usually measured on your upper arm and is a measure of the pressure in the brachial artery, the major artery in the upper arm. Your blood pressure number is usually expressed as the systolic pressure over diastolic pressure and is measured in millimeters of mercury (mmHg). For example, a blood pressure of 120/80 refers to 120 as the systolic pressure and 80 as the diastolic pressure.
See also: What Should Your Blood Pressure Be?
Does Weightlifting Increase Blood Pressure?
Most studies that investigate the relationship between exercise and blood pressure measure that actual resistance in the vessels themselves (such as the brachial artery), but don’t actually measure the heart pressure. The pressure in your vessels is called your “peripheral” resistance, and the pressure in your heart is called your “central” resistance.
This is important because it’s the actual stress that your heart is exposed to during exercise that you should be worried about, and it turns out that even though your peripheral resistance goes up during exercise (especially when you hold your breath with something like a Valsalva maneuver), studies that measure central resistance have found that the actual pressure in your heart isn’t even elevated above resting values!
Since you’d have to actually feed a tube called a catheter into the heart or use special equipment for an echocardiogram to measure something like this, it’s no surprise that most personal training manuals instruct personal trainers to simply measure blood pressure with a blood pressure cuff on your arm. But it turns out that even if that number is high, it doesn’t necessarily mean the heart is getting too stressed.
How Your Body Regulates Blood Pressure
It’s also important to understand that your blood vessels can change their size and thus affect the resistance that your heart has to pump against.
One way that your body increases blood flow and cardiac output during exercise is by dilating your arteries (making them bigger) and actually decreasing the resistance (peripheral resistance) that the heart pumps against. For a long time, exercise scientists believed that cardiac output decreased during weight training because contracting muscles somehow squeeze your blood vessels and make them shrink, which would increase peripheral resistance and dangerously raise blood pressure. Thus, it was assumed and still is assumed by many exercise professionals and physicians, that weight lifting is not safe for people with heart disease because it puts too much stress on the heart.
But when you lift a heavy weight, you also produce adrenaline, and adrenaline causes the arteries in your muscles to dilate, which causes a decrease in peripheral resistance, an increase in cardiac output, and no changes in blood pressure that are dangerous to the heart. As a matter of fact, the squeezing actions of contracting muscles actually "milks" blood back to your heart. This means that for people with high blood pressure, lifting weights may actually be less stressful to the heart than aerobic exercise, which doesn’t result in that same milking action!
So don’t be shy about heading to the gym and lifting heavy stuff – it will do your heart good.
Do you have more questions about whether weight lifting is bad for your blood pressure? Ask away at Facebook.com/GetFitGuy. See you there!