Bladder pressure is measured in degrees of leg crossing. While this is different for each person, averages can be taken and then normalized for the individual.
```       Male     Female
Pants   45       20
Dress    0*       0
```
* - while men do wear kilts, it is generally accepted that any separation of the legs that result in any of the thigh showing is far too much.

The units of bladder are scaled from 0 (normal leg separation) to 100 (legs crossed at a 30 degree angle). Thus for the average woman wearing pants with legs parallel (0 degrees) one is looking at the beautiful legs of a bladder pressure of 40 units. Compare this to a male (wearing pants of course) with legs parallel who would have a bladder pressure of about 60. The difference here has to do with the amount of initial separation to reach parallel legs.

There are two factors in bladder pressure those are theoretical amount of fluid and theoretical bladder size. Both of these are affected by the distance to the nearest toilet though in different ways. Only one variable changes at a time relating to the velocity relative to the nearest toilet.

Theoretical amount of fluid
As the distance to the nearest toilet increases, the perceived amount of fluid in the bladder increases linearly while the bladder remains constant in size. Right after voiding ones self it is rare to need to go right again, and if that case does arise there is very little liquid to deal with. However, along the interstate between distant rest stops (as you pass the sign "rest stop 3 miles, next rest stop 100 miles") once the rest stop is passed, there will be an incredible rush of liquid to the bladder.

Theoretical bladder volume
Once the velocity begins to move in the direction of the closest toilet the size of the bladder appears to shrink exponentially. This is especially the case when the closest toilet is a 'friendly' one (a toilet that has been sat on before by the one needing to use it). This is especially noticeable after getting out of a car for the purpose of urination as the pressure in the bladder seems to soar to extremes in the space of a few minutes or seconds. Fortunately for most of us, we always just make it in the nick of time (darn these zippers!).

Increasing the velocity to the nearest toilet only makes the rate of increase go up faster - time is not part of the function of pressure as related to distance. It is theorized that anyone approaching the speed of light in the direction of a toilet will explode in a fine mist of urine.

Distance is not measured as the crow flies but rather as the fox runs. The fact that an outhouse exists on top of the cliff 100 feet above you means little if you have to walk a mile to get there - it is the mile distance that enters into the equations.

It should be noted that this phenomenon also applies to also to other liquids leaving the body - nausea and diarrhea.