I've had this issue for a year and a half after a layoff. And in my first run I noticed I would get this burning sensation and I had to stop and take a break. This is a recurring issue of myn for all high cardio exercises such as boxing and it almost immediately presents itself when I up the pace of my training. Its unbearable and I and dumbfounded how I cannot find any other posts related to this issue. It sucks because I really want to improve in my boxing, and just last day I had to leave my gym 5 minutes in my training, because I was so discouraged, which I am regretting today. I am positive I have a abdominal hernia because I get sharp pains when I sit in odd positions, but I haven't seen anyone suffer the burning sensation that I have with it. So this is a new one for me. Anyone with advice or experience something similar?