Overview

Inflammatory bowel disease (IBD) describes “conditions that cause severe tummy pain and diarrhoea”. It is a long-term disease and occurs in two main forms, with both being chronic bowel-relapsing inflammatory disorders, Crohn’s disease and ulcerative colitis. These conditions are characterised by periods of exacerbation and remission, significantly impacting the quality of life for those affected. While the exact cause of IBD remains unclear, it involves a complex interplay of genetic, environmental, and immunological factors. Conventional treatment strategies, including medication and surgery, aim to reduce inflammation and control symptoms. Exercise and physical activity have well-known health benefits and a potential role in managing IBD.

Symptoms

• Blood or mucus (clear slime) in poo
• Bleeding from the bottom
• Diarrhoea for longer than 4 weeks
• Feeling constantly tired
• Losing weight unintentionally
• Stomach pain

Pathophysiology of IBD

The aetiology of IBD is not fully understood but the following 4 factors are all integral to the pathogenesis: genetics, environment, microbial factors and immunological factors.

Genetics

Genetics play a part in the development of IBD, with several susceptibility gene loci being identified. Susceptibility gene loci refer to specific locations on the genome when DNA sequence variations make an individual more susceptible to developing IBD. However, the heritability discovered is only attributed to 20-25% of these loci¹. Although there are these “missing genes”, it is hypothesised that gene-gene interactions could explain this.¹ Consequently, research and understanding gene interactions should be prioritised to understand the heritability and pathogenesis of IBD¹.

Environment

Environmental factors play a major role in IBD pathogenesis and here is a list of potential risk factors for IBD.¹

• Antibiotics – they increase the chance of developing IBD due to their disruption of the microbiome.
• Air pollution – evidence suggests it could partially cause Crohn’s disease and ulcerative colitis as well as increasing hospitalisations for both.
• Diet
• Drugs – NSAIDS have been linked with an increased chance of developing Crohn's disease and ulcerative colitis
• Geography
• Psychological element
• Smoking – this is the most studied environmental risk factor of IBD
• Social stress – people with lower stress levels have a decreased likelihood of having IBD
• Vitamin D deficiency – often observed in IBD patients

Microbial factors

It has been discovered that compared to healthy people, individuals suffering from IBD have faecal microbiomes that have significantly lower biodiversity. IBD patients also have a more unstable microbiota, which should be stable from a young age. This disruption to the microbiome plays a role in the development of IBD with differing proportions of certain bacteria causing inflammation and disease.¹

Immunological factors

IBD pathogenesis involves dysfunctions in both the innate and adaptive immune responses. The innate immune response is the body's quick, non-specific defence against infections, while the adaptive immune response involves immune cell activation and is a slower, targeted defence that learns to recognise and remember specific pathogens. 

With IBD, there is a key focus on abnormal T cell responses, including T helper (Th)1 in Crohn's Disease and Th2 in Ulcerative Colitis, as well as the emerging role of Th17 cells¹. T helper cells are an immune cell used in the immune response to fight infection and disease so an abnormal response explains why IBD is present in some individuals. Recent research highlights the importance of innate immunity factors like epithelial barrier integrity, autophagy, and cytokines such as interleukin-23 (IL-23), challenging the traditional Th1/Th2 paradigm.¹

Benefits of exercise and physical activity in IBD

General benefits of exercise

It is important to understand the general health benefits of exercise to understand how it could aid individuals suffering from IBD. Moreover, it is good for IBD patients to improve their overall health as well as specifically managing IBD. Independent of someone’s body mass index, exercise reduces all-cause mortality, mostly by lowering cancer and cardiovascular disease risk.²

 Bone mass density and muscle mass are also improved through regular exercise, reducing osteoporosis likelihood. Not only does exercise aid with physical health, but it also improves people’s mental health and well-being. Carrying out physical activity releases the hormone serotonin, which improves people’s mood and reduces the likelihood of depression for example.

Specific benefits for IBD patients

Exercise provides crucial benefits for IBD patients, including reduced disease severity and flares, improved gut motility, and enhanced immune function. Regular moderate exercise has been linked to a lower risk of gastrointestinal issues like constipation and a 20%–25% reduced risk of colorectal cancer, which is particularly important for those with a history of colonic inflammation.² 

In addition, exercise enhances the quality of life, reduces stress levels, and boosts functional capacity in patients with IBD. While pharmaceutical treatments are effective, they often have serious side effects and may not fully alleviate symptoms. Exercise offers a complementary approach, helping to counteract IBD-related complications like decreased bone density and muscle mass.³. Studies indicate that increased physical activity can help prevent disease flare-ups, particularly in patients with Crohn's disease in remission.⁴ Even moderate activities like walking or yoga have been shown to improve quality of life without adverse effects.

Mechanisms by which exercise may influence IBD

Exercise may influence IBD through several key mechanisms. Studies in non-IBD patients indicate that engaging in low-to-moderate intensity exercise enhances immune function, which may be advantageous for individuals with IBD. It is hypothesised that moderate exercise exerts anti-inflammatory effects by reducing visceral fat, which in turn lowers the release of pro-inflammatory cytokines, and by stimulating the release of myokines like IL-6 during exercise sessions.² IL-6, in particular, has been shown to increase the release of glucagon-like peptides, which are involved in repairing damaged intestinal mucosa.

In animal models of colitis, exercise has been found to decrease the expression of pro-inflammatory cytokines such as tumour necrosis factor-alpha ( TNF-α) and IL-1β while increasing IL-6 and the anti-inflammatory cytokine IL-10.² Additionally, exercise helps attenuate stress-induced barrier dysfunction and ameliorate colitis. Through these mechanisms, exercise may positively impact both the development and progression of IBD.²

Types of exercise and recommendations for IBD patients

• Aerobic Exercise
  • Examples: walking, cycling, swimming
• Strength Training
  • Importance of muscle maintenance and bone health.
  • Guidelines for safe practice
• Mind-Body Exercises
  • Yoga, Pilates, and Tai Chi
• Tailoring Exercise Programs
  • Individual considerations: disease severity, current fitness level, and flare status

There is a lot of research supporting mild to moderate-intensity exercise. However, there are mixed results on high-intensity exercise with it potentially being harmful.. Therefore, mild to moderate intensity should be prioritised and high-intensity exercise should be carried out with caution until there is more conclusive research.

Potential risks and considerations

Although exercise is recommended to help with managing IBD, there are some potential risks and considerations to evaluate:

• High-intensity exercise limits blood flow to the gastrointestinal system and may be harmful to IBD patients. Patients are worried about this exacerbating these symptoms
• Flares: if a patient is suffering from a flare where their symptoms are more severe, exercise may need to be avoided or modified
• Risk of overtraining: it is important to balance adequate rest and recovery to avoid overtraining and impacting the IBD

Summary

IBD, including Crohn's disease and ulcerative colitis, impacts quality of life with chronic symptoms and inflammation. Exercise offers significant benefits for IBD management, complementing traditional treatments. Moderate-intensity exercise improves overall health, reduces disease severity, and enhances gut motility and immune function. It may also lower the risk of colorectal cancer and counteract complications like decreased bone density.

Exercise works through mechanisms such as reducing visceral fat and promoting anti-inflammatory cytokines. While moderate exercise is beneficial and safe, high-intensity activities should be approached cautiously due to potential risks. Tailoring exercise to individual needs and conditions can enhance physical and mental well-being, making it a valuable addition to IBD management strategies.