First things first: Does exercise help in getting better or does it increase inflammatory processes?
In my n=1 experience, it is really difficult to judge. There always have been times when increased training resulted in higher crohns activity which resulted in blood loss which quickly impaired performance. So the training effect was more than compensated by the loss in aerobic power. On the other hand, training relieved a lot of stress induced inflammatory effects and I have seen that in my daily HRV monitoring.
However, science is also a bit indifferent, but generally suggests that training is not harmful.
In this recent (IMHO important) study on young patients, the effect of HIIT training and training at moderate intensity did NOT increase inflammatory markers (such as TNF-alpha), but increased immune cells. “Youth with Crohn’s disease can engage in distinctly different types of exercise without a significant acute exacerbation of inflammation.”
Exercise and Inflammation in Pediatric Crohn’s Disease
This study suggests that High intensity and moderate intensity training does not do any harm:
High-intensity interval training and moderate-intensity continuous training in adults with Crohn’s disease: a pilot randomised controlled trial
Quote: “We hypothesised that supervised endurance exercise training (either as HIIT or MICT) is a safe and effective strategy for improving cardiorespiratory fitness, fatigue, quality of life and mental health in people with CD.”
However, still some further studies are suggested to fully understand the effects, whether being harmful or beneficial.
In another study Alan Couzins pointed me at, HIIT training was associated with an increase of inflammatory markers, which basically is no surprise, as inflammation is the starting point of adaptions.
Cytokine and Sclerostin Response to High-Intensity Interval Running versus Cycling
I have been unsure for a long time about my training. At least I am at a point that I have stopped worrying too much on whether this or that workout may be harmful to me. If my gut feeling tells me to that today is time for putting the hammer down, I will go all-out, and if I feel that I better take it easy, I will rest.
Cheers
Martin
edit:
Disclaimer: I am no doctor. All written above is my own opinion, not an advise how to cope with our disease 