Altered muscle-immune-gut axis response to eccentric exercise in men with well-controlled type 1 diabetes: a pilot...

Eccentric-dominant exercise is a key component of many sports. It is also associated with exercise-induced muscle damage and activation of inflammatory responses. Physical activity, including sports, is one of the cornerstones in the treatment of type 1 diabetes (T1DM). However, the integrated response of the muscle-immune-gut axis to eccentric-dominant exercise in individuals with type 1 diabetes (T1D) remains poorly understood. This is the first study to evaluate the integrated muscle-immune-gut response to eccentric exercise in people with type 1 diabetes.

The study comprised 39 physically active men (20-39 years old); 19 participants with well-controlled T1D, treated using continuous subcutaneous insulin infusion (CSII), and 20 healthy volunteers-control group. They performed a 30-minute downhill run (-10% inclination angle) at 60% VO₂max. Blood samples were analyzed at baseline, 1-hour and 24-hours post-exercise assessed markers of muscle damage (LDH, myoglobin), inflammation (IL-6, TNF-α), hormonal responses (testosterone, cortisol), and gut-related response (zonulin).

However, in men with T1D, eccentric exercise triggers significantly more severe and prolonged inflammatory response, higher IL-6 concentrations, TNF-α and values of muscle damage markers, lasting up to 24 hours, compared to healthy controls. Increased cortisol levels may indicate a prolonged physiological response to exercise stress, while heightened zonulin levels may reflect changes in the gut-immune response following exercise with a predominance of eccentric contractions.

In active men with T1D, eccentric exercise triggers more intense, prolonged inflammatory and metabolic responses compared to healthy controls. This underscores the muscle-immune-gut axis, necessitating individualized training loads and specific recovery strategies to optimize exercise adaptation in this population.