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Training & Nutrition Learn how to develop a training schedule that's good for you. What should you eat and drink on your ride? Learn everything you need to know about training and nutrition here.

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Old 07-18-04, 07:44 PM   #1
cnudell
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Intense exercise and fainting sensations

Lately, after sitting or “position horizontally” for a while, when I stand up, I feel dizzy.
This usually occurs after long exercise session (cycling or gym).
It’s as if my blood pressure is so low that blood does not get to the head fast enough.
If I rest a day or two, I don’t get these “fainting” sensations.

Any similar experiences?
What am I doing wrong (eating, drinking, vitamins)?
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Old 07-18-04, 08:20 PM   #2
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It could be dehydration. My doctor tests for dehydration by making me lie down for a couple of minutes, then takes my blood pressure when I sit up. Try drinking more and make sure you're getting enough sodium.
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Old 07-19-04, 11:48 AM   #3
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You are not doing anything wrong. If you are in shape, you probably have a low heart rate and relatively low blood pressure. When you quickly stand up, your heart rate does not shoot up very fast (thanks to good conditioning) resulting in a drop in blood pressure to the brain. If you have a low blood pressure, the resulting drop can make you feel lightheaded for the few seconds it takes for your blood to get pumped back up there.

It's called transient orthostatic hypotension (sounds scary, eh!) and is common. I found an abstract to a study that concluded that the phenomenon is more pronounced in people having higher calf blood flow. Who better than cyclists to have high calf blood flow?

There is nothing to worry about unless your symptoms last longer than a few seconds. Of course, if you tend to do things like black out, or are concerned about it, go see your doctor.
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Old 07-19-04, 04:36 PM   #4
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Originally Posted by cnudell
Lately, after sitting or “position horizontally” for a while, when I stand up, I feel dizzy.
This usually occurs after long exercise session (cycling or gym).
It’s as if my blood pressure is so low that blood does not get to the head fast enough.
If I rest a day or two, I don’t get these “fainting” sensations.

Any similar experiences?
What am I doing wrong (eating, drinking, vitamins)?
Are you getting these sensations right after exercise? If so, one thing you may want to consider is that when you do exercise, a majority of the blood is shunted to the muscles that are doing the exercise. With an inadequate cooldown (or sudden ceasing of exercise), the blood can remain "pooled" or trapped in the legs,. When you do stand, you will feel a lightheadedness or dizziness, caused by a sudden shift of position and a lack of blood going to the brain, which could cause you to collapse. I had this happen once to a student after my cycling class. He'd worked out strenuously during class, then didn't take the time I requested for him to cool down. When we got off the bike to stretch, he dropped to the ground and laid there. Then he began twitching, and we ran over there and got him away from the bike. I had one student run and call the operator of the gym so she could call 911, then proceeded to raise the guy's legs to get the blood pumping back to his brain. Within 45 seconds, he was back to normal and standing up. For your next exercise, do take the time to do a longer cooldown- try 10 minutes. If you have a heart rate monitor, aim for 55- 60% max heart rate. Once you have cooled down, stretch as normal, and if you still feel dizzy, lay on the floor and find a way to elevate your legs over your heart (about 1- 2 feet). If this doesn't work, my next advice would be to see a doctor immediately, because there may be something wrong, and you don't want bikeforums to diagnose you in the event that there's a real problem no one knows about.

Keep us updated on how things work out for you.

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Old 07-20-04, 04:55 AM   #5
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I do like Koffee says and do a cool down after all my rides, even the rest days. I roll into my neighborhood and do a 3 mi loop at I ride at 115 HR or lower to cool down the legs and body. I try to ride for 10 - 15 min like this I start out this way also. Found that I feel better than if I just jump on the bike and ride and get off when I was done. The best cool down for me is riding with my 8yr old daughter after my ride. She like to beat up on daddy and win Gives me quality time with her and encourages her to ride while I teach her the proper way to ride around people and traffic.
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Old 07-20-04, 10:54 AM   #6
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I get these, too, primarily for the reasons Supcom describes, primarily after a long, difficult ride. If I drink a after such a ride, I have to take extra care to stand slowly, preferably near something I can hang on to for balance, and wait for it to pass, otherwise I'll be on the floor in 15 seconds.

Skip the beer? It's better not to stand!
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Old 07-20-04, 11:14 AM   #7
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Originally Posted by roadbuzz
I get these, too, primarily for the reasons Supcom describes, primarily after a long, difficult ride. If I drink a after such a ride, I have to take extra care to stand slowly, preferably near something I can hang on to for balance, and wait for it to pass, otherwise I'll be on the floor in 15 seconds.

Skip the beer? It's better not to stand!
Just be sure to set the beer down first. No sense spilling good beer.
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Old 07-24-04, 10:48 PM   #8
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I get lightheaded sometimes when I stand as well. Just like you describe, it only happens on days I ride, it only lasts a few seconds, and if I take a day off, it doesn't happen. I came to the conclusion (I took a wild guess ) by myself that it was either related to my low blood preasure, or low blood sugar. I tried eating more incase it was the latter, and have noticed it doesn't really seem to happen when I eat more. I haven't really kept track of the occurances though, so that may just be coincidence.
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Old 07-25-04, 04:43 PM   #9
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Hello All,

I am the original poster of this thread and I am reporting improvement!

Reading the replies on this forum and other, I believe it is related, in my case, to dehydration and lack of sodium.

I increase water drinking and salt intake and the symptoms as reduced drastically.
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