I have had this problem on and off. Sometimes when I ride and 99% of the time it is when I am getting started from a stop or it is the first few miles of a ride. I find myself out of breath and it feels like it is coming from my legs. So what is this? I also have a bad habit of breathing thru my mouth instead of inhaling thru the nose and then exhaling out of the mouth. (which I was told was the best way). What do you all think?