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leinosaur
Mar 8, 2004, 9:50 PM
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Twice after belaying from a standing position I have begun to see floating spots before my eyes. I thought at first it was dehydration or the sun, but it happened again, on another day, in the shade.
I now think it's due to a slight pinching of the nerves in the neck, caused by leaning back my head to keep a sharp eye on the climber.
Happily, the spots & slight headache went away when I changed to a reclined belay.
Any of youse ever experience this?
curious,
leinosaur
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mother_sheep
Mar 8, 2004, 9:54 PM
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Are you standing up and locking your knees? That might be another problem.
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leinosaur
Mar 8, 2004, 10:00 PM
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well, probably I'm locking the knees, too. Disregarding the advice of former-waitress girlfriends, if so. Is that what happens? Spots?
leinosaur
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reprieve
Mar 8, 2004, 10:00 PM
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yeah, that just sounds like a lack of blood circulating to your head. If it goes away when you recline you should be fine.
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jt512
Mar 8, 2004, 10:00 PM
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In reply to: Twice after belaying from a standing position I have begun to see floating spots before my eyes. I thought at first it was dehydration or the sun, but it happened again, on another day, in the shade. I now think it's due to a slight pinching of the nerves in the neck, caused by leaning back my head to keep a sharp eye on the climber. Happily, the spots & slight headache went away when I changed to a reclined belay. Any of youse ever experience this? curious, leinosaur
I'm not sure what you mean by "floating spots," but sudden onset of "floaters" should be attended to promptly by an ophthalmologist, as it can foreshadow a retinal tear or detached retina.
-Jay
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reprieve
Mar 8, 2004, 10:01 PM
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In reply to: well, probably I'm locking the knees, too. Disregarding the advice of former-waitress girlfriends, if so. Is that what happens? Spots? leinosaur
ummm...i don't think locking your knees would cause you to see spots, it seems like that would just make one of your legs fall asleep. but i could be wrong
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reprieve
Mar 8, 2004, 10:04 PM
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In reply to: In reply to: Twice after belaying from a standing position I have begun to see floating spots before my eyes. I thought at first it was dehydration or the sun, but it happened again, on another day, in the shade. I now think it's due to a slight pinching of the nerves in the neck, caused by leaning back my head to keep a sharp eye on the climber. Happily, the spots & slight headache went away when I changed to a reclined belay. Any of youse ever experience this? curious, leinosaur I'm not sure what you mean by "floating spots," but sudden onset of "floaters" should be attended to promptly by an ophthalmologist, as it can foreshadow a retinal tear or detached retina. -Jay
I think what he's talking about is not serious at all. I used to them all the time (some people call it a "head rush")... I think leinosuar is referring to the same thing, just a few dark spots and a fuzzy feeling in the head until the blood circulates and then you're fine. not a serious problem at all.
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mother_sheep
Mar 8, 2004, 10:08 PM
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In reply to: In reply to: well, probably I'm locking the knees, too. Disregarding the advice of former-waitress girlfriends, if so. Is that what happens? Spots? leinosaur ummm...i don't think locking your knees would cause you to see spots, it seems like that would just make one of your legs fall asleep. but i could be wrong
I locked my knees last week while giving a presentation and I saw spots. I relaxed and started walking while I was talking. Then I was fine. Years ago while standing at attention for about 1 hour, I locked my knees then too. I saw spots but I also passed out. :oops:
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reprieve
Mar 8, 2004, 10:25 PM
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Hehe, I have a similar story. I was in drumline in high school. We were practicing in the 100 degree heat on the football field one day. One of my buddies had apparently locked up his knees...our instructor is talking to us about something, and this guy just collapses with his drum on. Thankfully he didn't get hurt, and now it makes a good story.
Needless to say, it would be very bad if this happened while you were belaying.
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jt512
Mar 8, 2004, 10:28 PM
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In reply to: Hehe, I have a similar story. I was in drumline in high school. We were practicing in the 100 degree heat on the football field one day. One of my buddies had apparently locked up his knees...our instructor is talking to us about something, and this guy just collapses with his drum on. Thankfully he didn't get hurt, and now it makes a good story. Needless to say, it would be very bad if this happened while you were belaying.
This sounds like the birth of an urban legend: Locking your knees makes you pass out. Can anybody site a medical reference for this?
-Jay
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reprieve
Mar 8, 2004, 10:34 PM
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In reply to: In reply to: Hehe, I have a similar story. I was in drumline in high school. We were practicing in the 100 degree heat on the football field one day. One of my buddies had apparently locked up his knees...our instructor is talking to us about something, and this guy just collapses with his drum on. Thankfully he didn't get hurt, and now it makes a good story. Needless to say, it would be very bad if this happened while you were belaying. This sounds like the birth of an urban legend: Locking your knees makes you pass out. Can anybody site a medical reference for this? -Jay
I really wish I could...I'm a studying physics, so a desire for scientific understanding is in my nature. However, I can only attest to it from experience, I can't explain it. I'd be interested to see what people say.
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sixter
Mar 9, 2004, 12:05 AM
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In reply to: In reply to: Hehe, I have a similar story. I was in drumline in high school. We were practicing in the 100 degree heat on the football field one day. One of my buddies had apparently locked up his knees...our instructor is talking to us about something, and this guy just collapses with his drum on. Thankfully he didn't get hurt, and now it makes a good story. Needless to say, it would be very bad if this happened while you were belaying. This sounds like the birth of an urban legend: Locking your knees makes you pass out. Can anybody site a medical reference for this? -Jay
According to the Univeristy of Michigan, yes, standing for long periods of time with your knees locked can induce fainting. http://www.med.umich.edu/.../pa_fainting_hhg.htm
Why? I don't know. It would be nice to know why.
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jt512
Mar 9, 2004, 12:21 AM
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In reply to: In reply to: In reply to: Hehe, I have a similar story. I was in drumline in high school. We were practicing in the 100 degree heat on the football field one day. One of my buddies had apparently locked up his knees...our instructor is talking to us about something, and this guy just collapses with his drum on. Thankfully he didn't get hurt, and now it makes a good story. Needless to say, it would be very bad if this happened while you were belaying. This sounds like the birth of an urban legend: Locking your knees makes you pass out. Can anybody site a medical reference for this? -Jay According to the Univeristy of Michigan, yes, standing for long periods of time with your knees locked can induce fainting. http://www.med.umich.edu/.../pa_fainting_hhg.htm Why? I don't know. It would be nice to know why.
That link says:In reply to: To prevent fainting caused by standing too long, explain to your child that keeping the knees locked interferes with recirculation of the blood. If your child must stand for long periods of time, he should pump the blood by repeatedly relaxing and retightening the leg muscles.
So, there you go.
-Jay
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luke
Mar 11, 2004, 8:06 AM
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This is a well known occurance, particularly common among soldiers standing at attention. Basically the veins in the legs widen and allow blood to pool in the lower extremities, eventually causing unconsciousness due to lack of blood to the brain. Moving the legs or just statically "pumping" the muscles compresses the veins and returns blood to the torso and head.
If you are interested, this is related to what is called "harness trauma". Hanging motionless in a harness for even quite a short period of time can cause rapid pooling of the blood in the legs, unconsciousness, and (it is believed) eventually death. The problem is exacerbated by the possibility of serious injury (including heart and other major organ failure) if blood flow is restored after a prolonged period without circulation, as the blood is de-oxygenated and can contain high enough levels of respiratory byproducts to be toxic. "Crush Trauma" is another variant in which circulation is limited by external pressure (eg if much of the victim is buried). Neither of these extremes occurs if you just stand too long with the knees locked, as you will just black-out, fall over, and restore blood flow.
On a purely random note, I read somewhere once that horses have a similar problem. If they stop moving their legs while standing they will lose consciousness. I dont know if this is true.
For more (much more - this is 100+ pages of PDF) on harness trauma, see
http://www.hse.gov.uk/research/crr_pdf/2002/crr02451.pdf
or do a google search. Some of the links you get from google will mention the locked-knees issue too.
Luke
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leinosaur
Mar 11, 2004, 12:58 PM
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Thanks y'all; well-spotted! I'm sure the locked-knee issue was my prob & I'll be sure to pump the muscles if I must stand. Love that reclining, though - easier on the ol' neck.
This is the cleanest resolution to a question I've seen in a while. Nice that it was mine!
tnx agn
leinosaur
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