Hey ,

It depends a little on what causes the tightness. It is possible your tightness could be caused by the Hiatal Hernia. In this case the exercises in the movie I showed you could help you.

I reposted it here so you don’t have to search for it!
In general, with Hiatal Hernia stretching the sides of the trunk of the body will cause relief. Another great video with stretches you can try out you can find here. Most are easy, but with some, you need some equipment.
 
But perhaps you can tell me more about what type of tightness you are experiencing. I assumed you are not feeling tight muscles, but more like something is pressing inside out – am I correct?

Exercise in general for the prevention of symptoms
I don’t know if you have some form of exercise routine you are doing now but in general, exercise will help motility and can have a positive influence on gastroparesis.

I am talking about mild to moderate exercise here since aggressive exercise is likely to worsen your symptoms. Just like with food, you might need some time to discover triggers, but here are some tips that are in general safe with an hiatal hernia and acid reflux:
• Walking
• Cycling
• Dancing
• Yoga (without the inversions) or Tai-chi
• Running:
Just a little tip here: running can also negatively influence acid reflux symptoms if you do this too aggressively or too long, so here my advice is to start to build up easily and run for a few minutes followed by walking.