Understanding How Fitness Affects Digestive Diseases

Physical exercise influences the gastrointestinal (GI) tract through changes in motility, permeability, immune responses, and microbiota composition, according to a review evaluating the relationship between exercise and GI conditions.¹

Moderate exercise was found to provide patients significant benefits, such as improved quality of life in those with inflammatory bowel disease and irritable bowel syndrome, as well as reduced colorectal cancer risk and relief from constipation. On the other hand, high-intensity exercise may lead to adverse effects like reflux and GI bleeding in patients with these GI conditions.

The literature review, published in the Journal of Clinical Medicine, was conducted to address the growing interest in understanding how physical exercise affects the GI tract, an area that has historically received less attention than other physiological systems. While early research focused primarily on exercise's adverse GI effects, such as nausea, diarrhea, and bleeding in athletes, more recent studies have highlighted its potential benefits, including disease prevention and improved digestive health.

Physical inactivity is a major global health risk, contributing to 5.5% of annual deaths.² Regular physical activity significantly reduces the risk of more than 25 chronic diseases and improves quality of life. Health guidelines recommend at least 150 minutes of moderate or 75 minutes of vigorous exercise weekly, with greater benefits observed at higher volumes.¹ Walking more than 7000 steps daily also lowers disease risk.

Physical activity includes any energy-expending movement, while physical exercise is structured activity aimed at improving fitness. Exercise can be intermittent (using the phosphagen system for short, high-intensity efforts) or continuous (aerobic system for long-duration, lower-intensity activities). The intensity and type of exercise influence its effects on the GI system: Moderate exercise brings metabolic and anti-inflammatory benefits, while extreme exercise can cause GI symptoms like nausea and diarrhea, especially due to intestinal ischemia and dehydration.

The authors theorized that exercise’s influence on GI function is based on intensity and duration. Moderate activity improves motility, reduces constipation risk, and supports gut health through neuroendocrine changes and increased vagal tone. Low-intensity exercise speeds gastric emptying, while high-intensity exercise delays it and may cause GI distress.

Anaerobic activity can enhance gastric accommodation and reduce satiety, possibly due to lactate buildup and cytokine release. Exercise also affects intestinal permeability through changes in tight junction proteins. Factors like microbiota shifts, stress, and use of nonsteroidal anti-inflammatory drugs can worsen permeability.

Strenuous or prolonged exercise, especially in heat, reduces blood flow to the gut, risking ischemia, inflammation, and barrier disruption. Overall, exercise has both positive and negative effects on GI health depending on the type and individual response.

Although aerobic exercise has been well studied, the authors noted that the impact of resistance training on GI health requires further research.

"Adjusting exercise intensity and frequency to maximize benefits without worsening gastrointestinal symptoms is essential in all these conditions," the authors concluded.

References

1. Severo JS, Alves da Silva, AC, Barros dos Santos BL, et al. Physical exercise as a therapeutic approach in gastrointestinal diseases. J Clin Med. 2025;14(5):1708. doi:10.3390/jcm14051708

2. Global strategy on diet, physical activity and health. World Health Organization. Accessed April 16, 2025. https://www.who.int/publications/i/item/9241592222