Exercise as it relates to Disease/Exercise and its impact on Crohn's disease

Background to Crohn's Disease and Exercise
Crohn’s disease (CD) is an autoimmune, relapsing inflammatory bowel disease (IBD) of the gastrointestinal (GI) tract, with extra intestinal complications. CD affects 1 in 250 Australians aged 5 to 49. Continuous inflammation results in abdominal pain, fever and diarrhoea with the passage of blood; while poor nutrient absorption causes fatigue and malnutrition. CD can also cause bowel obstructions, perforations, and so on; some of which can be life threatening. CD is currently incurable, and therapeutic management to induce remission is used to control symptoms, improve quality of life (QoL), and limit disease activity and progression.

There is limited insight to the effect exercise has on CD. Low-intensity exercise, and moderate-intensity exercise have no adverse effects on CD, despite the latter showing increased plasma inflammatory markers. This is encouraging as CD patients experience muscle weakness, decreased bone density and QoL; which improve with exercise therapy. These implications of CD result from both the nature of the disease (malnutrition, fatigue etc.) and high glucocorticoid use to control acute inflammation during flares, causing skeletal muscle catabolism and bone loss.

Article Analysis
The following is an analysis of the article "Exercise Decreases Risk of Future Active Disease in Patients with Inflammatory Bowel Disease in Remission" by Jones et al. (2015) which investigated the association between exercise intensities and CD activity. Though the study involved both CD and ulcerative colitis as part of IBD, only CD will be investigated.

Source of Research
Crohn’s & Colitis Foundation of America (CCFA) conducted the research on adults who were a part of an internet-based cohort. This self-reporting cohort provides researchers with clinical data previously lacking in administrative or retrospective reviews.

Research Type
The research analysed self-reporting data from CCFA sponsored adults (≥18 years old), allowing for quantitative analysis.

What did the research involve?
The research involved selecting a cohort of CCFA sponsored adults (≥18 years old) with IBD from the CCFA partners data-base who completed both baseline and 6 month surveys. Only participants in remission at baseline were included; this was determined using the short Crohn's Disease Activity Index (sCDAI) with a score of ≤ 150 indicating remission. Participants were excluded if they had an ostomy (inability to report bowel movements) and/or any comorbidities affecting the ability to exercise. The resulting CD cohort involved 1308 participants. The Godin leisure-time activity index was used to determine activity levels, using the median score to divide data, developing ‘higher’ and ‘lower’ exercise activity categories. At 6 months the CD activity of the two exercise groups was analysed to observe any relationship between disease activity and physical activity.

Basic Results
At 6 months, the higher exercise category had less active disease than the lower exercise category. Fifteen per cent of the higher exercise category developed active disease, compared to 20% of the lower exercise category, both of which were significant.

Interpretation of Results
These results indicate that individuals in remission who increase their levels of exercise have a 32% decrease in risk of active CD at 6 months. This decrease was still significant when all variables were accounted for: such as BMI, current smoking status and disease duration. Conversely participants on steroid therapy significantly increased their active disease with increased exercise. This was interpreted to be the result of incorrect perceived health from drug-induced remission, rather than true remission.

Jones et al. (2015) acknowledged that this finding challenges previous suggestions that common exercise induced GI symptoms, such as increased urge to defecate, will be exacerbated in CD subjects. The proposed mechanisms for these symptoms involve increased motility and inflammation of the GI tract. These statements are indeed held in the literature, as increased GI symptoms and inflammatory markers are a consequence of medium to high intensity exercise. Despite this, low to moderate exercise interventions have not been shown to adversely affect CD.

While physiological benefits, such as improved skeletal health and QoL are postulated, impacts on psychological health is absent. Depressive symptoms have been shown to worsen CD activity and though exercise treatment is known to significantly lower depression, the research between anti-depressive effects of exercise on CD patients is limited. Along with this, the anti-inflammatory effects of exercise and its potential impacts on inflammatory disease activity were not discussed.

Research Implications
Current research indicates that this study is really a foundation for future research. Previous studies focussed on specific interventions, rather than finding strong correlational evidence to support the rationale for exercise in CD sufferers. This neglected basic quantitative information, such as true effect magnitude, effect size, and clinical significance to the IBD community. This research shows that despite the hypothesised adverse effects of exercise in CD patients, it still decreases risk of future active disease. This is important, especially for Australia, as CD sufferers have higher morbidity and mortality rates than the general population.

Limitations
Limitations within the study include problems with validity; as self-report data was used where participants may over or underestimate their symptoms and exercise involvement. The cohort may lack accurate representation of the IBD community as participant recruitment was confined to certain aspects, such as English language and technology requirement. The type and duration of exercise is not recorded, which may have allowed for evaluation of the current recommended exercise prescription of 20/30min at 50% maximal heart rate for 3 days a week with resistance training 2-3 times per week.

Conclusion
CD sufferers have lower rates of disease activity when they participate in higher levels of exercise, hence, patients in remission with low exercise levels should be encouraged to increase their physical activity. Mechanisms underlying this association may relate to a range of physiological and psychological factors. This research provided the area with substantial quantitative data allowing future studies to progress findings, but would have benefited from more detailed analysis.