How Eccentric Exercise Affects People With Type 1 Diabetes: What New Research Shows

Researchers wanted to understand how the body responds to eccentric-dominant exercise—movements that emphasize lengthening muscles under tension, like running downhill—in people with type 1 diabetes. This type of exercise is common in many sports and can cause muscle soreness and inflammation, but how these responses differ in type 1 diabetes has not been well studied.

The study included 39 physically active men aged 20–39. Nineteen had well-controlled type 1 diabetes managed with continuous insulin pump therapy, and 20 were healthy controls without diabetes. All participants completed a 30-minute downhill run (at a -10% incline) at 60% of their maximum aerobic capacity.

Scientists took blood samples before exercise, 1 hour after, and 24 hours after to track several markers: muscle damage (LDH and myoglobin), inflammation (IL-6 and TNF-α), stress hormones (testosterone and cortisol), and a gut-related protein called zonulin that reflects intestinal immune function.

Men with type 1 diabetes showed a significantly stronger and longer-lasting inflammatory response to the eccentric exercise. Inflammatory markers—especially IL-6 and TNF-α—remained elevated at higher levels 24 hours after exercise in the type 1 diabetes group compared to controls.

Muscle damage markers also stayed elevated longer in people with type 1 diabetes. Additionally, cortisol levels (a stress hormone) remained higher, suggesting the body may experience prolonged stress from this type of physical activity.

Zonulin levels—a marker of gut-immune changes—also increased more in the type 1 diabetes group, indicating that eccentric exercise affects the gut-immune system differently in people with type 1 diabetes.

This pilot study is the first to examine how the muscle, immune, and gut systems respond together to eccentric exercise in type 1 diabetes. The findings suggest that exercise recovery may be different for people with type 1 diabetes, particularly after activities that emphasize eccentric muscle contractions.

The results do not mean people with type 1 diabetes should avoid exercise—physical activity remains a cornerstone of diabetes management. Rather, they highlight that the body's response to certain types of activity differs, which could help inform how individuals with type 1 diabetes plan their training and recovery. More research in larger and more diverse groups is needed to fully understand these differences and develop personalized exercise guidance.

Source: Frontiers in physiology. Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.