I am 41 and also have this problem, but I have Postural Orthostatic Tachycardia Syndrome (POTS) which was diagnosed by a tilt table test. Do you also experience any shortness of breath or does this also happen when you stand still (like when standing in line)? Also does this happen more when you are dehydrated? Your symptoms could easily be caused by othostatic hypotension, but as I have found, it can also be a little more involved. I am a cardiac nurse and never really knew about POTS until mine began to seriously start effecting my life. With your symptoms and your family's extensive cardiac history, I would recommend seeing a cardiologist. Good luck!
It sounds like "orthostatic hypotension." Google it. Given that you're extremely fit, the chances are that your BP is quite low now. When you squat, bend down, or generally get your head lower than usual--and then stand up quickly--your circulatory system has to make a fast adjustment to get your BP high enough to supply blood to the brain. If your BP is naturally quite low, there may be a bit of a delay, so your brain is briefly short-changed.
I believe this tendency may increase with age, but don't quote me. ;-)
In any case, mention it to your doctor, and in the meantime, give your brain a break by standing up a little more slowly in general. See if that helps.
I have the same question as you! I've never had a satisfactory answer either. I am also a runner and a swimmer, and find the symptoms to be more pronounced after a harder workout. My pet theory is that squatting down causes blood to get trapped in the legs, where it gets depleted of oxygen. Then when you stand up, the oxygen depleted blood escapes and flows throughout the body, including to the brain which causes light headedness for a few seconds, until fresh oxygen rich blood flows again.
I also have those symptoms that you mentioned above. Have a CBC (Complete Blood Count). My doctors told me, it was related to Anemia (low hemoglobin).
In doing a search for you, I found something:
"If you exercise often and are in good shape you might occasionally experience dizziness and lightheadedness when you stand up quickly. This is generally nothing serious, and occurs due to a slow heart rate. If you exercise often and are in good shape you might occasionally experience dizziness and lightheadedness when you stand up quickly. This is generally nothing serious, and occurs due to a slow heart rate.
When you stand up quickly gravity pulls blood from your brain towards your feet and blood doesn't return to the brain until the next heart beat. With a slow pulse, this takes a second or two and that is enough time to feel the lack of oxygen in the symptom of lightheadedness or dizziness. It is also related to something called postural hypotension. This results from a decrease in blood flow to the brain, due to a drop in blood pressure upon standing up.
As long as it occurs only occasionally, you don't really need to worry. If you have constant and severe dizziness with changing position you should see a doctor to rule out an underlying condition such as an irregular heartbeat."
This is a copy and paste from somewhere else, but caught my eye when it mentioned exercise. You mentioned that you exercise regularly. Have you had your heart rate checked? I know you say it happens when you squat, but maybe it's the same affect.
Take care, Ally