Postural hypotension.

[AussieTrees]

Yesterday was out fishing and it was windy,very little cover,so with back to the wind,I was facing the water and late afternoon sun.The sun was also reflecting off the surface back to me,very glaring.

 

So to avoid the brightness and wind,I squatted low sitting on my calves with feet firmly on the ground.

Sat this way legs started feeling numb,so stood up,caught me by surprise,head dizzy,felt as if was going to blackout/ faint.

 

The fishing was slow,only got one bite,broke the line snap,gone.

So got interested in nearly fainting,so returned to squatting,and periodically would stand up abruptly.

 

Never did blackout completely,but a few occasions had quickly bend knees to prevent or restore blood pressure,continued this activity (game),for a couple of hours.

 

That evening whilst in bed,the sensations were lower legs mostly below knee felt warm to hot.

Checked electric blank was off,really hot,had to get up for a while,eventually slept well.

 

This morning can still feel residual sensations.

[Mudfoot]

Google "fainting lark".

A fun game for the young.

[Orion]

When you squat it forces the blood out of the legs into the trunk, which your body registers as an increase in blood pressure, and lowers vessel tension to compensate. The same thing happens when a person is strangled. Even if the strangle hold is released, the body already lowered vessel tension to try and relieve the perception of tension. Often times people who are strangled die anyway, even if the choke hold is released, because their body does not restore balance in time. 

 

Ok so the strangling example is kind of weird but I just remember it from med school. When you're squatting your body decreases vessel tension because the posture is forcing more blood upward. When you stand up too fast, the vessel tension is still low and hasn't adapted to standing, so you're more prone to fainting. You probably already have low blood pressure to start with. You should go from squatting to sitting for 30 seconds, and then to standing.

Edited March 22, 2017 by Orion

[AussieTrees]

Orthostatic hypotension, also known as postural hypotension[1] or shortened to orthostasis and colloquially called head rush, occurs when a person's blood pressure falls when suddenly standing up from a lying or sitting position.

 

It is defined as a fall in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg when a person assumes a standing position.

 

It occurs predominantly by delayed constriction of the lower body blood vessels, which is normally required to maintain an adequate blood pressure when changing position to standing. As a result, blood pools in the blood vessels of the legs for a longer period and less is returned to the heart, thereby leading to a reduced cardiac output.

 

Mild orthostatic hypotension is common and can occur briefly in anyone, although it is prevalent in particular among the elderly and those with known low blood pressure.

[Orion]

Orthostatic hypotension, also known as postural hypotension[1] or shortened to orthostasis and colloquially called head rush, occurs when a person's blood pressure falls when suddenly standing up from a lying or sitting position.

 

It is defined as a fall in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg when a person assumes a standing position.

 

It occurs predominantly by delayed constriction of the lower body blood vessels, which is normally required to maintain an adequate blood pressure when changing position to standing. As a result, blood pools in the blood vessels of the legs for a longer period and less is returned to the heart, thereby leading to a reduced cardiac output.

 

Mild orthostatic hypotension is common and can occur briefly in anyone, although it is prevalent in particular among the elderly and those with known low blood pressure.

 

Obviously a copy and paste job. Source?

[Kar3n]

Obviously a copy and paste job. Source?

https://en.wikipedia.org/wiki/Orthostatic_hypotension