What made me think about it was how i try and do a bit of exercise on the running machine on our ship. (mental trying to stay on it.)
Anyway, it's got a heart monitor and running is boring. So, when i'm doing it i have wee competitions with myself trying to control heart rate. When i'm breathing heavy my heart rate is off the scale. Been trying to reach 200 but 198 is the max so far. You get all dizzy and your not sure what the fuck is going on. If i keep changing the speed of the machine to keep the heart rate down, i still function all right. Breathing just through my mouth makes exercising more difficult.