07-08-2004, 01:20 AM
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#24 (permalink)
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| | Re: dizzy when riding
On 7 Jul 2004 20:39:30 -0700, dwcleck@bellsouth.net (Dwayne) wrote:
>I've been cycling for the past 2 years about once or twice a week for
>about 2 hours at a time, around 25 miles each trip. For about the
>last 4 weeks I get really dizzy and slightly nauseated about 30
>minutes into the ride and I have to stop and sit down for a while or I
>feel like I'm going to get really sick. After about 15 minutes of
>sitting down, standing doesn't help, I get slowly better and then I
>seem to do ok no matter how hard or how far I ride after that.
>Usually I eat a banana or two for breakfast with water. I've
>sometimes had a honey bun with coffee and I've been dizzy with either
>type of breakfast. I come home and check my BP and its about 125/75.
>I've had some high BP in the past but never to a point the Dr. wanted
>to put me on meds. After I began cycling 2 years ago the BP readings
>have been consistently low. Could it be that while cycling my BP gets
>too low? Or could it be getting too high during the ride, when I
>can't check it? I've also been riding in the mornings when its
>cooler. I live in Alabama and the summers are awful. 95 degrees with
>90 percent humidity. I ride in the mornings when its about 75 degrees
>and about 80 percent humidity. Could it be the high humidity? Other
>riders wtih me, wife, brother in law, others do not experience the
>same thing. I am 41 years old and slightly overweight, 205 lbs. 6 ft
>2 inches tall. My ideal weight is about 185 - 190.
>
>Any advice?
Terry Morse reported on this on 6/7/04 to a similar post concerning dizzy
feeling after biking. Not sure if it's the same thing, but FWIW:
http://groups.google.com/groups?hl=e...news.covad.net
<snip>
You're describing post-exercise hypotension, a well known (but not
well studied) symptom. When you stop exercising, the heart rate
quickly slows down. This reduces the blood flow, and the blood
pressure drops. Putting your head between your knees should prevent
fainting. There's an article here that briefly explains what's going
on:
http://www.afpafitness.com/articles/Pressurelink.htm
(scroll down to "Cardiovascular response following exercise")
I supposed a "warm down" period would reduce the plummet in blood
pressure, but sometimes that's not possible. On a group ride last
year, one of the riders got to the top of a long climb and began a
gentle descent. He passed out, fell and broke his femur. Not good.
--
terry morse Palo Alto, CA http://bike.terrymorse.com/
<snip>
-B
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