Why does my body shut down after exercise sometimes?

I’ve honestly had some very similar incidents lately. And the only relief for me is laying down as well, especially being that I become intensley nauseated and lightheaded. But occasionally this will happen to me when I am doing no physical activity. I know I have gluten intolerance, and so after I discovered that, I figured it was the cause of these incidents for me. The good news is that you recover from it after awhile, but I’d still say its worth looking into. I mean, does this feeling only happen when you workout?

Maybe you’re pushing yourself a little bit too much? You might want to go see a doctor or something..

Ya, curiouscat is right, it can happen when you overwork your body, that’s certain.

My girlfriend suggests that you might not be breathing correctly. Your brain needs large amounts of oxygen, and when heavily working your large muscle groups, they utilize lots of oxygen, so they might be “stealing” it from your brain. I always find the hardest thing to focus on when working out is my breathing.

Or you might be dehydrated.

This happens to anyone that overwork their muscles. It is because muscles, particularly big ones, require a lot of oxygen both during and after exercise.
It needs a lot of oxygen during exercise to put out the energy, while after the exercise the oxygen helps carry away all the lactic acid generated from all the hard work out.
Thus, your body cannot get enough oxygen fast enough to regenerate.
Try some breathing exercises.

All these could be contributions but diet could be part of it as well. I used to become quite lethargic around 2pm each day. I was eating high protein foods and working out regularly but my body was shutting down. I learned through a diet for allergy testing that the seed/nut mixture recommended by my nutritionist was causing my system to slow.

You sound like you listen to your body and alter things to make it work better. At some point you do need to get an opinion outside your own self. I think you should talk to a doctor.

even after exercise, blood flow is still increased to your muscles – to get lactate and metabloic waste out of themand to replenish their nutreint and oxygen stores, and to your skin – to get heat out. Typically, the way most americans hydrate themselves, the body has enough blood to power 2.5 organ systems running full steam, and then enough left over to keep everything else in “standby mode.” Even though it doesn’t seem like it, your muscles are still running “full-steam” in terms of blood delivery several minutes after exercise is complete. In this set up, it’s usually the brain which gets the other 0.5. plus the washout of lactate and other toxins can make someone feel nauseous and woozy.

bottom-line: aerobic exercise can increase your tolerance, and proper hydration can help keep your blood volume approriate

You don’t say whether you are using targets for heart rate while exercising. Here are a couple of tests:

“Determining the Intensity of Your Workout
The “talk test” is the simplest way to tell if your level of activity is too challenging or needs to be increased. You should be able to talk to someone
while exercising. So, if you’re too out of breath to talk, you need to slow down. You can also use a formula to calculate your target heart rate. You can then test your pulse while you’re exercising to see if you’re exercising at the right pace.
For moderate intensity, you should exercise at 55— 65% of your maximal heart rate for your age group. Be sure to check with your doctor before using this formula. Some heart
and blood pressure medications can change your target heart range.

Determining Your Target Heart Rate for Exercise
1. Subtract your age from 220 to get your maximal heart rate (MHR).
2. Multiply MHR by 55% (.55) and by 65% (.65) to get the lower and
upper part of your target heart range.
3. Test your pulse at your wrist or neck for 10 seconds immediately after you
stop exercising. Multiply this number by 6 to determine if your heart rate
is in your target range.

Going to reiterate- see your doctor. I’ve a feeling a cardiac stress test is in order.

I get this same exact issue. It is worse when I am out of shape. I can only do a few lifting exercises when I am really out of shape before this starts to come on. The more that I overload myself while exercising the worse that it can potentially get afterwards. It will not start to come on until I have finished exercising. The more that I calm down the worse that it gets. If I lay down it will accelerate dramatically. I have fixed this by running for 10 minutes after my workout, but it limits me severely even so. I was a very intense fitness enthusiast all throughout highschool, working out multiple times a day for long stretches of time. The more I stopped exercising the more I became incapable of returning to exercise because of this effect.

The feeling is generally like I am slipping away and becoming nauseous. It definitely has something to do with my brain not getting enough oxygen. I start to panic because it feels like I am doing what I can only interpret as dying. At a certain point it always bottoms out and then quickly goes away and then I am fine. Please let me know if you have seen a medical professional who has given you any kind of useful advice.

I am very hesitant to go to one because I can only assume they will give advice similar to what I am seeing in these comments, which is not useful. If I don’t want to feel it I know how to fix it. I just run for a while. But I will never be able to exercise to my full potential because running will only compensate for so much of it. And when I say “full potential” I really mean that I want to work out to an unhealthy extent. Which is why I don’t know why a medical professional would want to help me. I can very easily exercise the amount that a doctor would recommend to stay healthy.

I think that it has to do with the fact that my heart rate is very good at recovering, and that this is actually working against me. As I said, I was very, very athletic for 5–6 years.

I definitely focus on breathing whenever this happens. The fact that that doesn’t work proves to me that it doesn’t have to do with the rate of oxygen entering my lungs, it has to do with the rate that my lungs can uptake the oxygen and get it to my brain.