This might sound like an odd question. But, if you have Inflammatory Bowel Disease (IBD) or Irritable Bowel Syndrome (IBS) this can be an important question without a definitive answer.
If you read my Shareposts regularly, then you've probably figured out that there is no one right answer for all IBD or IBS sufferers' symptoms. What might work for one patient may send another running to the bathroom just thinking about it. The same tends to be true with exercise.
The general rule I've seemed to notice over the years, both with my personal experience and in talking with other patients, is that exercising during an acute flare-up is a bad idea, especially for IBDers.
With IBD, a flare-up typically includes bloody diarrhea, low-grade temperature, joint pain, extreme fatigue, and loss of appetite. And you have to remember that IBD is an autoimmune disorder, so when you're in a flare-up that means that your immune system is depleted and working overtime. So, for IBDers having a flare-up, it's probably best to curtail your exercise until the flare is under control, you're eating more regularly, your energy levels have increased, and any joint pain has decreased.
For IBSers the question of when, and when not, to exercise isn't so clear-cut. The better question might be, how intense of a work-out or exercise session can your body tolerate? Most people I've talked to with chronic gut issues, like IBS, especially those who are diarrhea-predominant tell me that vigorous or intensive exercise, like running or weight lifting or football, etc., actually make symptoms worse. Better, and more tolerable, exercise options include things like walking, bicycling, yoga, and swimming.
I also think people need to learn to listen to their body when it comes to exercise. What might feel right one week may be too much or too intense another week. If that's the case you may not have to stop exercising altogether, but rather cut-back on time or intensity or try another easier exercise.
I have both IBD and IBS. When I'm feeling well and healthy I can hike for miles, ride my bike, speed walk, swim, or do yoga 4-5 times per week. But when my IBD flares I almost always have to cut out my exercise until I get the flare-up under control. When my IBS rears its ugly little head I can usually continue to do activities like yoga or walking but cut-out more energy-intensive and jarring exercises like hiking, swimming, and bicycling.
Try different exercises and different lengths of time and see how your gut reacts. Listen to your body. Hear what it is telling you and make whatever necessary adjustments you need to. I had a gentleman email me a year or so ago. He was a competitive runner and had also been diagnosed with IBD a few months earlier. He noticed over a month or so period that when he was training for a marathon his IBD symptoms seemed to flare-up. But if he just went for a leisurely jog around his neighborhood with his son it didn't seem to cause him too many issues. He wondered, "Why?"
The best guess I could come up with is this: activities like running cause a lot of up-and-down, jarring motion within the body. Whether we realize it or not this causes our organs - and yes, these include our large and small intestine and stomach - to get jostled and jerked about and will undoubtedly cause an already sensitive gut to get angry.
I have tried running many times over the last 20 years and I just can't do it. My gut can be fine for days, weeks, even months then I go out and jog for 10 or 20 minutes and Wham-o I'm in the bathroom. So, I've heard my body telling me that it doesn't like when I run, so I don't. I can get a great workout from yoga, walking, hiking, and bicycling. I stay healthy and my gut stays happy.
So back to the original question, "Is exercise good for people with IBD or IBS?" The answer is going to be different for each and every one of us. And to find it out it will take a little trial-and-error, some effort on your part, and a lot of listening to what you body has to tell you. And remember, what your body likes one month it may not like next month and vice-versa. So, find a few different activities that you like to do so you can switch off here and there depending on how you're feeling.