By Dr Joe
You do recall my scary experience that I documented following an exercise regime. The experience was awful and indeed freaked out my Missus and my two sons.
My daughter was in University so was lucky to have escaped the drama that unfolded on the day. Lucky girl!
If you haven’t read about it, go here and satisfy that curiosity, otherwise this post won’t make much sense to you. Don’t worry, I won’t judge you.
No one is judging you on this website. See Part 1 of the story first and proceed back here.
Why am I sharing this post exercise sickness and dizziness experience with you?
Remember that acquainting yourself with my personal experience means if you ever hit a similar bump on your exercise routine, you won’t be too scared and will know what to do. It’s a learning exercise.
Now, I do just okay on the cardiac front. Not perfect but just okay. Even though I didn’t think the Part 1 of the drama was due to my heart complaining about the intensity of the exercise and reacting in a frightening way just to teach me a lesson, I still felt I needed to check things out.
The main reason is because I have and are trying to clear my cardiovascular risk factors out of my life. It might interest you know that I suffer from hypertension (high blood pressure), was overweight and also developed full blown metabolic syndrome. These are risk factors for heart attack.
It is the reason I embarked on a journey to change the way I live not by consuming more tablets, (Big Pharma would love that, won’t he) but by incorporating a lot of what you read about on this blog into my life.
Having those risk factors meant at the back of my mind, I needed to ensure I wasn’t making a potentially catastrophic assumption. I was also scarred from the event and had to scale back on the intensity of the exercise until I was doubly sure there was NOT a cardiac element to the Part 1 event.
So, what did I do next?
I went to see my Cardiologist. That’s what I did.
Told him what happened and straightaway he didn’t think the event was cardiac-related. We still needed to stress my heart to see if it was still coping well to workouts though.
I had to have a more recent ECG (EKG to my North American friends). Tick – It went fine.
Have an echocardiogram – Tick. Not perfect but hasn’t changed for the worse in the last 15 years. It was still exactly the same as it was 15 years ago.
I was glad about that actually. At my age, you’ve got to have some blemish, haven’t you? Mind you this is a body that has been battered with stress and it’s seen a couple of decades. So, can’t complain.
More importantly, I needed a more recent exercise-tolerance test which I did. Strapped to ECG (EKG) leads and a blood pressure cuff around my arm, off I went on to the treadmill.
Starts off gently and they gradually crank up the speed and the incline until you are out of puff. Kinda similar to what you do with High Intensity Interval Training workouts.
Secretly I think the folks who do the exercise-tolerance test actually enjoy what they do. It’s like being in charge of a “controlled torture chamber”.
“Think you are made of sterner stuff? Let’s crank it up and see how you cope then brother” is probably their mind-set every time someone steps on that treadmill wired up to their eyeballs.
Anyway, I coped well with the “torture” until I raised my hands up to signal fatigue and the treadmill was gradually brought to a halt. It so happened that my heart coped well.
> There were no unusual ECG (EKG) changes and my blood pressure response to exercise was good.Having said that, apparently my blood pressure does drop sharply after exercise and this important in grand scheme of things.
More about that later.
My exercise endurance was fine but a minute less than it was when I last did an exercise-capacity test 10 years earlier. Well, I am decade older now since that test and it is to be expected.
> All in all, it went great and I felt better reassured that the event was not cardiac in origin.
If it wasn’t cardiac what was it then…
What causes post exercise sickness, nausea, dizziness, lightheadedness?
Here is the skinny.
Feeling of nausea or being actually sick after exercise or workout can be caused by 2 main physiological explanations.
1. Blood supply changes
2. Blood pressure changes
Blood supply changes
I did mention this in the other post. Exercise places a huge demand on the human body. Muscles are at work and your brain too is seriously at work (you just don’t know it but your brain is). Your brain is responsible for your muscle coordination, regulation of your heart rate, regulation of your blood pressure and also heightening up your risk awareness.
On this account, both the muscles involved in the workout and your brain will demand that your heart supplies them with more blood. So will your heart itself (it’s got some more work to do remember) and your lungs – more oxygen is needed.
Your heart, brain, lungs and muscles effectively increase their blood supply in response to exercise at the expense of organs that don’t really need much supply at that point in time.
> Organs such as your bowel, kidneys and skin (initially) need little supply.
I say skin initially because as exercise progresses, supply to your skin increases as part of thermo-regulation to facilitate heat loss through sweat. Otherwise your body will overheat which is just as dangerous.
> The problem is that any slight demand on your bowels during or soon after the exercise can trigger a strong vasovagal response.
Symptoms of vasovagal response vary widely. I have culled the list of symptoms from this page for easy reference for you.
> “Episodes of vasovagal response are typically recurrent and usually occur when the predisposed person is exposed to a specific trigger. Prior to losing consciousness, the individual frequently experiences early signs or symptoms such as light-headedness, nausea, the feeling of being extremely hot or cold (accompanied by sweating), ringing in the ears (tinnitus), an uncomfortable feeling in the heart, fuzzy thoughts, confusion, a slight inability to speak/form words (sometimes combined with mild stuttering), weakness and visual disturbances such as lights seeming too bright, fuzzy or tunnel vision, black cloud-like spots in vision, and a feeling of nervousness can occur as well.The symptoms last for a few seconds before the loss of consciousness (if it is lost), which typically happens when the person is sitting up or standing.”
In my case I did not pass out or lose consciousness but felt lightheaded and dizzy. This is the result of the stimulation of the nerve we call, the Vagal Nerve. The vagal nerve exerts influence on the rate at which your heart beats amongst other functions.
When it is stimulated, the vagal nerve slows down your heart rate so much so you experience some of those symptoms mentioned above.
Here is a case reported in a Korean medical journal about a 39-year-old man who had a similar experience to mine. He was hypertensive and recently became diabetic. He was on medications similar to mine. In some respects, you would think we were twins only I am several years older. In his case though, he was actually fainting repeatedly.
The doctors in his case confirmed his diagnosis by giving him a very cold beverage. He experienced dizziness during the test after drinking the cold beverage.
With me, I had a very cold water soon after the exercise and that was the trigger for the vagal nerve stimulation moderated with the fact that my bowel blood supply was not optimal at the time. That’s one explanation.
Now the other:
Blood pressure changes during exercise, workouts or vigorous physical activity
One thing that is certain is that exercise whether aerobic or resistance workouts will always result in blood pressure changes.
When you start a workout your blood pressure will rise and it will keep rising to varying degrees depending on the type of workout or exercise until it plateaus. Then blood pressure falls after the vigorous physical activity is over.
During exercise, there is an override of sympathetic activity on the heart. Sympathetic nervous system is what drives heart rate up and also increases the strength of the pumping heart muscle.
Sympathetic activity makes the heart go faster and harder unlike the opponent the para-sympathetic which slows it down and quietens it. It will interest you to know that the para-sympathetic nervous system is mediated by the vagus nerve I talked about earlier.
An increase in sympathetic activity is necessary because of the increased demand from the organs directly involved in the workout. Increased demand for nutrients and oxygen which has to be met by increased blood supply.
> Both sympathetic and para-sympathetic cannot fire themselves up at the same. One has to dominate depending on what your body is doing. So, when more blood is needed by the relevant workout organs as happens during vigorous physical activity, sympathetic system goes into over-drive and the para-sympathetic cools off until exercise is over.
When you are done with your workout the para-sympathetic takes over and that is when blood pressure can drop, sometimes drop low enough to cause the phenomenon of Post Exercise Hypotension or in lay man’s terms post exercise low blood pressure.
This is a normal physiology. It’s just that in some individuals this after-work out drop in blood pressure is somehow exaggerated leading to symptoms of the vasovagal I talked about earlier.
If you want to get really geeky about the phenomenon of post work out blood pressure changes, here is a very good review of the topic
Post exercise hypotension (low blood pressure) is something that occurs across genders, races, healthy people and the not-so-healthy people.
This study compared healthy volunteers with individuals who have Stage 2 or 3 chronic kidney disease. The healthy subjects were in the control group. Both the chronic kidney disease sufferers and the healthy volunteers were subjected to random exercises and rest periods.
They found the blood pressure to be lower in both groups after the aerobic exercises than after the rest periods even in those individuals with the chronic kidney disease who usually have high blood pressure in tow as part of the package for chronic kidney disease.
Some differences in the degree of fall in blood pressure after vigorous physical activity can be seen between races.
These researchers looked at the blood pressure patterns after exercise between the Chinese race and the Caucasian race. They studied 62 individuals (30 Caucasians and 32 Chinese both sexes) assessing the blood pressure changes after 30 minutes and 60 minutes following an aerobic workout of 45 minutes.
The researchers found out the fall in blood pressure was lower in the Caucasians subjects than in the Chinese.
Even time of day does have an influence on exercise drop in blood pressure. One research did show that falls in blood pressure after a workout occurs at a bigger magnitude in the morning than in the evenings.
> Anyway, the point is blood pressure does fall after vigorous physical activity to varying degrees between individuals, between races, times of day, and state of one’s health too.It’s just that the drop can be dramatic enough in some individuals to cause symptoms like fainting, dizziness, light-headedness, nausea, vomiting, diarrhoea etc.
So how do you prevent post exercise symptoms like sickness, fainting, dizziness, light-headedness?
I should say this upfront. These tips are not for everyone. Most people do their aerobic and resistance training without any problems.
So the tips below may not apply to you if are not troubled by post workout nausea, fainting, dizziness, diarrhoea, light-headedness etc.
Just carry on as normal but if you belong to this unfortunate club, you may find the tips handy.
>> Ensure adequate hydration before starting a workout. Preferably at least 30 minutes before because if you hydrate too close to the beginning of the exercise, it can trigger a vagal response.
>> Delay drinking after your workout until your body has cooled off completely. I know you are thirsty but hold off for at least 15 minutes after your work out before drinking.
>> Do not eat too close to your workout sessions. Eating gives your bowels work to do when your body has other more pressing needs. A full stomach is an unnecessary demand on your heart when you have a workout around the corner.
>> When you drink, you may want to have isotonic drinks (drinks formulated with electrolytes and some sports drinks) as your main fluid for rehydration. These drinks are designed to help stabilize your blood pressure such that swings towards very low readings are avoided. Very low drops will lead to those symptoms.
>> Of course, you don’t have to invest in expensive sports drinks. Good ol’ plain water is just as good. However, avoid extremes of temperature. Don’t have very cold water or hot drink so soon after the workout especially if it was an exercise of high intensity. Learn from my experience. Not pleasant.
Room temperature water is fine. You can drink icy cold water later on say a good 30 minutes later after your exercise.
This tip will apply to those who experience symptoms after high intensity training exercise. High intensity workouts can be very demanding on your body.
> This means the blood pressure changes may be very dramatic. To prevent any undesirable side effects, you should not stop your exercise abruptly. Ease off gently to allow your body time to carefully adjust itself. This step prevents huge shock to your circulatory system and makes for an easier, gentler cooling off.
If you feel dizzy, faint, lightheaded, and you are in the upright position, quickly lower yourself onto the floor. The idea is to encourage blood flow to your brain plus being in the prone position also helps with stabilizing the blood pressure too.
If your heart is unable to pump sufficient blood to your brain because you are standing up, you may faint and become unconscious and probably have a seizure too. Best avoided.
After all said and done, if you have any doubts about how you feel following exercise, see your doctor for reassurance tests.
Suggested further reading:
1 Obscure Trick To Make ANY Exercise Program More Effective
Dr. Joe