Stomach Pain and Punchng Bag Workout

Hello,
A few months ago, I started getting a stomach pain when I was punching a bag with a lot of effort at a local gym. If i refrain from putting my body into and using my stomach to generate power I dont feel any pain, but if i use my stomach I get a massive cramp and have to sit down for a while. I tried taking a break from hard workouts for about a month, but once i started using my stomach for punching the bag again it came right back. I think it may be a pulled muscle in my stomach but i'm not sure. i'm 22 in good shape, not overweight, dont smoke, don't do drugs, but occasionaly drink.

I'm just wondering if it actually is a pulled muscle, and how to prevent it, and make it go away.

Thank you, I'm looking forward to a response

[mikebnick]

I have searched the net trying to find out something about a similar problem.  I play a lot of tennis, often 3+ hours at a time.  Towards the end and after playing my stomach cramps.  Is this your problem?  Tennis also uses core muscles, as would punching a bag. I have been told it is an increase in metabolism that causes this cramping.  But would like any clarrification from someone who knows a little more.  I do know that when I take something like Mylanta or phasyme (sp??) it doesn't affect me quite so badly.  Maybe try something like that.