I am sure we all understand why we experience increased heart and respiratory rates when we work out. Oxygen is metabolized in the cells when muscles work, which causes an increased demand for oxygen so we breathe faster and our heart pumps faster to supply our body with the needed oxygen. What may not be so commonly understood is the reason why we get light-headed during or right after a heavy lift. Understanding why this happens can help an athlete recover from this feeling quicker and potentially prevent your friends from being able to post an embarrassing video of you passing out right after a lift. Funny to watch, but not funny if it happens to you.
Our respiratory drive, among other things, is controlled by the vagus nerve (the tenth cranial nerve). This is why we don’t have to think when to breathe, our body does it automatically. While there are many ways to stimulate the vagus nerve, we stimulate it when we take a deep breath and hold it throughout a movement, which is what we are supposed to do! Taking a deep breath, and tightening your core muscles during a lift is very similar to a technique used by medical professionals to slow the heart rate down called the Valsalva maneuver, which is used to treat elevated heart rates (supraventricular tachycardia). Both the Valsalva maneuver and holding your breath and tightening your core muscles during a lift, stimulate the vagus nerve, which tells the heart to slow down.
After the lift, we experience the light-headedness because the decreased heart rate makes it difficult for the brain to get the required amount of blood. This is similar to a vasovagal episode, where the brain does not get the necessary blood flow, and as a result we experience tunnel vision, tinnitus (ringing of the ears), light-headedness, and sometimes a temporary loss of consciousness. Luckily, once on the ground, the heart is no longer working to pump blood against gravity up to your brain, so the necessary amount of blood flow is restored to the brain, allowing you to regain consciousness.
So how do we prevent it? Obviously exhaling throughout a lift is not an option, if we want to maintain a solid, stable core, but one way to minimize the symptoms is to get yourself low to the ground. This accomplishes two things, first, if you do end up passing out, you’re closer to the ground so you don’t have to fall as far, and secondly, you decrease the height from your heart to your brain, allowing blood to get to your brain easier. Personally, I usually place my hands on my knees and bend my legs a bit so if I do feel as if I am going to pass out, I can simply sit down.
I hope this brief, and hopefully easy to understand explanation helps you understand what is going on inside your body and prevents you from ending up in a video on the internet. Next time you lift heavy and feel light-headed, decrease the distance your heart has to pump blood to your brain by getting low and you’ll feel better in a few seconds. Let me know what you think, what methods you use, or any other questions you might have by leaving a comment below.