Forum home Road cycling forum Training, fitness and health

dizziness when standing

TheGreatGatsbyTheGreatGatsby Posts: 818
edited February 2008 in Training, fitness and health
and momentary blindness.

whats theat all about then?

Gats :?:

Posts

  • DaveyLDaveyL Posts: 5,167
    Low blood pressure?
    Le Blaireau (1)
  • Mike WillcoxMike Willcox Posts: 1,770
    and momentary blindness.

    whats theat all about then?

    Gats :?:

    Stop riding your bike for 5 minutes and eat a good meal.
  • J2R2J2R2 Posts: 850
    I have had this occasionally. I have never seen a doctor or done anything about it. It normally happens if I get up quickly after lying on my back or slouching on the couch.
    __________________________
    lots of miles, even more cakes.
  • Hey,

    If you're experiencing the dizziness/blindness when standing up then its likely to be due to postural hypotension ie. temporary low blood pressure when you sit up or stand up and is perfectly normal in healthy individuals.

    Its basically due to the distribution of blood in the circulatory system; normally about 70% of your blood is in the veins and venules of your body (capacitance vessels). As the blood in these vessels is at a much lower pressure than that in the arteries, venous return to the heart is affected by gravity. Obviously, if you are lying down this is not too much of a problem, but when you stand up the blood tends to pool in the feet, legs, etc. thus reducing the amount of blood returned to the heart. Consequently, preload is reduced (essentially the amount of blood in the heart when it contracts) and so the stroke volume (the volume of blood pumped by the heart in a one beat) is also less, so blood pressure falls and less blood reaches the brain, hence the dizziness/blindness.

    Fortunately, arterial pressure monitors (baroreceptors) pick up on this fall in blood pressure and evoke (via the medullary cardiovascular centres) a pressor response ie. increase your blood pressure to bring it back to a normal level, so the dizziness should be only momentary. If not, maybe see a doctor.
  • Gats :?:[/quote]

    Stop riding your bike for 5 minutes and eat a good meal.[/quote]

    And obviously the same problems experienced while out riding are nothing to do with postural hypotension (unless perhaps if you suddenly leap from a recumbent onto a proper bike...) and are probably due to hypoglycaemia. Similar symptoms cos your brain's deprived of glucose.
  • Ahh cool so nothing to worry about then.

    super!

    Gats
  • chrisw12chrisw12 Posts: 1,246
    Ahh cool so nothing to worry about then.

    super!

    Gats

    Well um... quite a lot to worry about really. The blackout can knock yourself out and you end up on the floor. It's happened to me and a mate both in the bathroom funnily enough (not at the same time) and led to both of us injuring ourselves in the fall.

    I find I get this worse if I haven't eaten properly and done a long ride. Blood sugar does seem to have an effect but since I'm not a doc. don't quote me on that.
  • This has happening to me twice in recent years . Both times I passed out and fell in the bathroom injuring myself . On both occasions I had got out of bed from sleeping . I went to the docs and then had blood tests and an ECG but they couldn't find anything wrong except having a low resting heart rate. In the end the only advice they could offer was to make sure I took my time and to get up slowly after waking which I try to do but normally forget .
    Luke
  • andy_wrxandy_wrx Posts: 3,396
    I've had this all my life - jump to feet quickly, go dizzy, vision goes tunnel-vision all silvery around the edges, loud buzzing in ears.
    Never fallen-over or actually fainted, but sometimes grab a chair or banister just in case.

    I've never really worried about it, have never dropped dead or anything. :)

    My blood pressure is at the lower end of normal, so I'd worked-out it must be something like La cucaracha explains, although (her ?) explanation is far more technically competent than what I'd worked-out for myself !
  • Passed out again Friday night . Scared the wife to death with the noise of me falling over. As per usual got up to go for wee then collapsed coming back to bed . Fortunately didn't hit anything hard this time . Must remember to try and get up more slowly .
    Luke
  • have you just walked out the pub when this happens? i get the same thing lol :twisted: :lol:
    felix's bike

    pedal like you stole something!!!
  • whyamiherewhyamihere Posts: 7,547
    I'd be getting myself to a doctor if it's not something I've always had. Having something like that develop isn't good, and could be very dangerous if you end up collapsing.
  • Brian BBrian B Posts: 2,071
    I passed out several times when I was a young lad with this but since adulthood I have only got really dizzy and darkened vision for a breif time. As soon I feel it coming - I.E. after just jumping off the couch I now instinctively crouch down to the floor which helps it pass for me more quickly and then after that I'm fine.
    Brian B.
Sign In or Register to comment.