I spit all the time when I'm running. Probably every 100/200m.
There are big differences between dreadmill running and proper (*ouch*) running. The air outside is [1]: usually colder, which stimulates salivary glands and sinuses, and [2]: the air is
moving, which again, increases the rate at which the above glands produce their respective, er, secretions.
I'm unfortunate enough to suffer from exercise-induced rhinitis and something called post-nasal drip, which means that not only does my nose run (faster than
I do), the excess snot flows down the back of my throat. If I don't clear my throat sufficiently or effectively enough, it can sometimes lead to me choking and retching. Hence my apparent overzealousness in clearing my mouth and throat.
Apologies for the words "secretions", "snot", and "retching"; but they were essential to the plot.
