Lightheadedness During Exercise
What It Means, and What We Can Do
I’m not praying, and I’m not getting emotional, usually.
After doing a heavy work set of squats, deadlifts, and overhead presses, I often need to take a knee.
Here’s one of my favorite anecdotes: a couple of years ago, I was doing a heavy set of deadlifts; I locked out at the top of a rep and dropped the weight. I felt light-headed, so I reached for the metal frame of the rack I was working in, but if I touched it, I don’t remember.
As far as I knew, the cord that powered the world was pulled, and the lights went out.
The power came back on, I was on the ground, and two guys were patting my back, trying to get me awake.
They told me what had happened. I was out for about ten seconds.
I dropped the barbell, reached up my left arm for the rack and just dropped. I fell against the rack in such a way that I ended up in a seated position, with my back leaning against it. They ran over and jostled me awake.
I called it a day, and they put the weights away for me.
The next day, I came back to the gym and told the staff what happened and asked if they could show me the video from the security cameras, of which, fortunately, there are several.
Sure enough, just like the guys said, I dropped the barbell, and then I dropped like the barbell--hard and loud, a nice reminder and demonstration of how powerfully gravity works unabated.
I banged and scraped my left arm on the way down, but I’m lucky that I didn’t crack my head open on the steel rack, the metal plates, even the floor.
Though this was the first--and last--time I had ever passed out while working out, it wasn’t my first foray into the world of lightheadedness, especially while working out.
A few months prior to this, the dizziness and lightheadedness would get so bad that I’d literally have to lay down between sets, lest I pass out and drop.
I didn’t know it at the time, but any light-headedness is a symptom of hypotension: low blood pressure.
We’ve all experienced this light-headedness and dizziness upon standing at least once or twice, which is called orthostatic hypotension.
In the context of exercise, where there are often wild but acute swings in blood pressure, both up and down, this lightheadedness and dizziness is called “exercise-induced hypotension” Sometimes, as with weightlifting, it’s referred to as “post-set induced hypotension”. There’s also “post-exercise hypotension” or “post-exercise syncope”. “Syncope” is the medical term for fainting and passing out. (For my word-philes out there, in linguistics, syncope is the loss of a sound within a word. Example: Chocolate as we pronounce it in Standard American (Awesome) English: Cho-clate.)
There are a few things that contribute to hypotension and dizziness, and there are a few things that we can do to address it. It can be a symptom of an acute issue, or it can be reflective of something more chronic.
Before getting into the contributing factors, due to its extreme obviousness and recognizability, hypotension is a good example of feedback from your body that you want to look out for and pay attention to. A small degree of hypotension may be normal in certain contexts and situations, but chronically, your body is showing you that something is off. And this doesn’t just apply to exercise and training, but any activity, as well as energy conditions while dieting. Part of being an intelligent exerciser and dieter is to look for these signs and signals and respond accordingly.
Moreover, I don’t want to go so far as to say that dizziness and lightheadedness during or after activity is normal, but it is, unfortunately, fairly common.
“Post-exercise syncope (defined as loss of consciousness or development of pre-syncope signs and symptoms during recovery from a bout of physical activity or exercise) is an alarming response to exercise which can occur in apparently healthy individuals, including athletes, even among healthy individuals and high-performing athletes.”1
Acutely, there are several simple reasons why you might experience lightheadedness and dizziness during physical activity. The easiest one is simple hydration.
Being underhydrated or dehydrated to any degree reduces blood volume, which makes it more difficult for the body to maintain blood pressure during activity, so heart rate, that is, cardiac output, increases. The body works hard to maintain balance, obviously, in all systems, and hemodynamics--blood pressure--is in constant flux during physical activity and exercise.
“Even mild post-exercise dehydration (≈ 1 % of body weight) increases resting heart rate (HR) and decreased tolerance to lower body negative pressure, implying impaired cardiovascular control.”2
I admit that I used to be terrible regarding hydration surround and during workouts, but we lose more water than we’re aware of with exercise, so we want to be sure that we’re adequately hydrated before, during and after. We want to sip on something throughout workouts, exercise, and activity. Our liquid intake should be proportional to the duration and intensity of the activity. If you’re going for a walk on a treadmill in an air-conditioned gym and then doing some calf raises and crunches, you don’t have to sweat it. If you’re doing CrossFit outside in the middle of a Southwestern summer’s day, it’d be a good idea to have a small cooler of Gatorade nearby.
Gatorade is as good a tool for exercise as any other workout gear because hydration isn’t just about replenishing water. We also need to consider electrolytes. Electrolytes are minerals--inorganic molecules--that conduct electricity in the body. They’re essential for many processes and systems, including hydration and muscular contraction. Examples are sodium, potassium, magnesium, and calcium.
“During endurance exercise, two problems arise from disturbed fluid–electrolyte balance: dehydration and overhydration. The former involves water and sodium losses in sweat and urine that are incompletely replaced, whereas the latter involves excessive consumption and retention of dilute fluids. When experienced at low levels, both dehydration and overhydration have minor or no performance effects and symptoms of illness, but when experienced at moderate-to-severe levels they degrade exercise performance and/or may lead to hydration-related illnesses.”3
If we’re underhydrated, we’re making it more difficult to maintain blood pressure, but we’re also putting ourselves at risk of hyperthermia. Our sweat helps dissipate body heat. If we chug more water, we signal to the kidneys to drop more water, which releases more electrolytes, which can actually exacerbate our dehydrated and hyperthermic conditions. The key point here is to have some food--something simple like an energy bar, dried fruit, even some candy will help--or a sports drink to help keep the electrolytes in there, thereby helping to maintain adequate hydration status.
Another thing that can help with hydration is our carbohydrate intake. Every gram of carbohydrate that we store in our liver and muscle--which is called glycogen--is accompanied by 3-4 grams of water. Folks doing low-carb diets aren’t carrying around as much water as they would with eating more carbs. (Don’t mistake this change in body weight for a change in body tissue. It’s a difference and shift in body water. Low-carbers effectively do a water cut.) When we use the glycogen in our muscles and liver during activity, that water is released into circulation, which can help maintain blood pressure.
There’s a ton more we could say about hydration, but the focal point is to be aware of your hydration status before, during, and after your sessions. You want to replace what you’re using and expelling. The strategies are summed up nicely here:
“Exercise performance can be compromised by a body water deficit, particularly when exercise is performed in hot climates. It is recommended that individuals begin exercise when adequately hydrated. This can be facilitated by drinking 400 mL to 600 mL [approximately 13 to 20 ounces] of fluid 2 hours before beginning exercise and drinking sufficient fluid during exercise to prevent dehydration from exceeding 2% body weight.
“A practical recommendation is to drink small amounts of fluid (150-300 mL) [approximately 5 to 10 ounces] every 15 to 20 minutes of exercise, varying the volume depending on sweating rate. Core temperature, heart rate, and perceived effort remain lowest when fluid replacement comes closest to matching the rate of sweat loss.
“During exercise lasting less than 90 minutes, water alone is sufficient for fluid replacement. During prolonged exercise lasting longer than 90 minutes, commercially available carbohydrate electrolyte beverages should be considered to provide an exogenous carbohydrate source to sustain carbohydrate oxidation and endurance performance. Electrolyte supplementation is generally not necessary because dietary intake is adequate to offset electrolytes lost in sweat and urine.”4
Carbs aren’t just helpful for hydration. Of course, blood glucose is a factor with hypotension. If you’re exercising several hours after your last meal, especially if you’re doing something endurant or particularly intense, you may find yourself getting fatigued and even a little light-headed after effortful sets.
“When the metabolism of skeletal muscles is greatly increased over a period of time, they begin to deplete their own glycogen stores and compete against the brain for the glucose available in the blood (e.g., glucose released from the liver).”5
When we get to this point, our nervous system becomes acutely impaired, which makes sense if we think about it. The brain and nervous system are at a point where they need to compete with exercising muscles for circulating glucose. The limited energy is impeding the brain and nervous system’s ability to best maintain hemodynamics--again, blood pressure and movement--due to inefficient constriction and dilation (relaxation) of blood vessels.
So, it’s not just carbs here but total food intake may also be at play. That’s to say, if you’ve been dieting or are acutely behind your energy intake for the day, and there’s just not a large supply of energy available to fuel everything, so your low energy status is also impairing your CNS--the central nervous system--to operate as best as it can.
A couple of final factors and considerations that can lead to lightheadedness during exercise: breath-holding and the movement itself. It’s typical for people to hold their breath during some portion of the movement when lifting weights. In fact, there’s a technique just for this: the Valsalva maneuver, a breath-holding technique which helps form a strong core, creating a brace and more stability for movements. It’s particularly used for the compound movements: squats, deadlifts, and bench press.
The only problem with such techniques is that it can even momentarily occlude blood flow somewhere in your body, that is, stop it, much like a blood pressure cuff getting too tight, requiring your body to adjust accordingly and quickly to the extreme and almost immediate changes in blood pressure. It’s more common to inhale as you lower a weight and then exhale as you push it, but the Valsalva maneuver would have you hold your breath through most of it. That is, you inhale before any movement, brace your core, like tensing your abs, do a squat or deadlift repetition, and then exhale and inhale in between reps. Do whatever’s more comfortable for you, but if anything, something like the Valsalva maneuver should only be used sparingly and only after a lot of practice with lighter loads.
The final thing that affects blood pressure isn’t really anything we can control, but it’s good to keep in mind. If you’ve ever gotten lightheaded, it was probably after a large effort with your lower body (or something going overhead). Our legs--specifically the quads and glutes) constitute the largest muscles in our bodies. When we do something like squats and deadlifts, especially something that is higher reps or with higher loads, there’s a lot of blood that needs to be shunted into those muscles to perform the work. As the blood is in the muscles, it’s out of circulation, so our bodies are trying to maintain blood pressure during sets. When the sets end, blood pressure drops, but we need a moment for the blood to leave the muscles, so there’s something of a mismatch. This is all normal and to be expected, but if we’re underhydrated or underfed, there can be a lag in normalizing blood pressure, which is when we get lightheaded.
Related to this is the actual movement of an exercise. A movement where our upper body shifts planes will also quickly affect blood pressure. Deadlifts are a great example, as are back extensions (sometimes called hyperextensions), good-mornings, and anything else we bend over to do, like rows and rear-delt flyes, as well as with total body movements like burpees.
To recap, here are things that can contribute to lightheadedness and dizziness while exercising or even doing any physical activity:
· Low hydration, which lowers blood volume, making it more difficult to maintain blood pressure.
· Low electrolytes, which help us maintain adequate hydration.
· Low glucose levels, which can literally and physiologically impair our nervous system’s ability to efficiently maintain blood pressure changes during activity.
· Low food intake and low energy availability.
· Breath-holding.
· Working large muscles very intensely without adequate recovery.
When I passed out doing deadlifts a couple of years ago, I had been dieting for a few months. It was late at night, so my circadian rhythm was already on the decline. I should have been getting ready for bed instead of trying to lift a heavy load. I was also tired, as well as hungry, which likely means that my blood sugar was lower, and I was probably underhydrated; I never took drinks with me to the gym and rarely used the water fountain. It was a time when I was bracing more and practicing breath techniques like the Valsalva, and, of course, deadlifts work just about all the muscles in the body, so a significant portion of blood was shunted out of circulation to help the muscles perform the work, and just by virtue of the movement--bending over and standing up--blood was quickly redistributed. Altogether, it was a perfect storm. I don’t know if we could design a better scenario for fainting.
The lessons here are: eat and hydrate adequately before exercise and workouts, hydrate during workouts--if it’s overly long, consider a snack--pay attention to where and when you may be holding your breath during movements, and know that bigger muscles inhale more blood during work, so don’t push it too much, and be sure to recover adequately between sets.
If you notice yourself getting lightheaded during exercise, it’s a flashing neon billboard that something’s off, so run through this checklist, listen to your body, and make the necessary adjustments in response.
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