I've been riding a few years now, probably averaging 65 miles per week. I'm still on the slow side, at least compared to many people I ride with, but not *too* slow.
But when I push myself hard -- up a hill is the most common case -- it hurts in my stomach, right below my lungs. It seems to be worse if I'm more bent over (as opposed to more upright) but it happens when I'm pretty much upright too. It sort of feels like somebody hit me in the stomach, though it comes on gradually rather than suddenly.
If it matters, I'm probably 40 lbs overweight, and have the usual "beer belly" of somebody with that weight and my age (42).
If I take it easy for a few minutes, it goes away completely, though it can happen again with a few minutes of hard exertion. It doesn't seem to matter if I have food in my stomach or not, though it might happen more easily if I haven't eaten.
This has happened during the last few years -- it hasn't really changed, though I think I can now push myself somewhat harder before it happens.
It's not really a big problem, but it's annoying, and I'm wondering if anybody has any ideas what it is. Do other people have this, or is it just me? I did mention it to my doctor during a checkup and he had no idea, but didn't seem to think it meant I should stop riding or anything like that (my health was good -- just lose some weight.)