Originally Posted by
CrankyOne
Picking up from the
http://www.bikeforums.net/commuting/...e-curious.html thread...
For a few of these, roughly 1/10 of 1% of the population, it is likely genetic and uncontrollable without meds or other intervention. For another similar size 1 in 1,000 group it is thought to be mostly stress/psychological.
The human body...a marvel of engineering, except for when it isn't.